This is as.info, produced by makeinfo version 4.8 from as.texinfo.START-INFO-DIR-ENTRY* As: (as). The GNU assembler.* Gas: (as). The GNU assembler.END-INFO-DIR-ENTRYThis file documents the GNU Assembler "as".Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,2006, 2007 Free Software Foundation, Inc.Permission is granted to copy, distribute and/or modify this documentunder the terms of the GNU Free Documentation License, Version 1.1 orany later version published by the Free Software Foundation; with noInvariant Sections, with no Front-Cover Texts, and with no Back-CoverTexts. A copy of the license is included in the section entitled "GNUFree Documentation License".File: as.info, Node: Top, Next: Overview, Up: (dir)Using as********This file is a user guide to the GNU assembler `as' (GNU Binutils)version 2.18.90.This document is distributed under the terms of the GNU FreeDocumentation License. A copy of the license is included in thesection entitled "GNU Free Documentation License".* Menu:* Overview:: Overview* Invoking:: Command-Line Options* Syntax:: Syntax* Sections:: Sections and Relocation* Symbols:: Symbols* Expressions:: Expressions* Pseudo Ops:: Assembler Directives* Object Attributes:: Object Attributes* Machine Dependencies:: Machine Dependent Features* Reporting Bugs:: Reporting Bugs* Acknowledgements:: Who Did What* GNU Free Documentation License:: GNU Free Documentation License* AS Index:: AS IndexFile: as.info, Node: Overview, Next: Invoking, Prev: Top, Up: Top1 Overview**********Here is a brief summary of how to invoke `as'. For details, see *NoteCommand-Line Options: Invoking.as [-a[cdghlns][=FILE]] [-alternate] [-D][-debug-prefix-map OLD=NEW][-defsym SYM=VAL] [-f] [-g] [-gstabs][-gstabs+] [-gdwarf-2] [-help] [-I DIR] [-J][-K] [-L] [-listing-lhs-width=NUM][-listing-lhs-width2=NUM] [-listing-rhs-width=NUM][-listing-cont-lines=NUM] [-keep-locals] [-oOBJFILE] [-R] [-reduce-memory-overheads] [-statistics][-v] [-version] [-version] [-W] [-warn][-fatal-warnings] [-w] [-x] [-Z] [@FILE][-target-help] [TARGET-OPTIONS][-|FILES ...]_Target Alpha options:_[-mCPU][-mdebug | -no-mdebug][-relax] [-g] [-GSIZE][-F] [-32addr]_Target ARC options:_[-marc[5|6|7|8]][-EB|-EL]_Target ARM options:_[-mcpu=PROCESSOR[+EXTENSION...]][-march=ARCHITECTURE[+EXTENSION...]][-mfpu=FLOATING-POINT-FORMAT][-mfloat-abi=ABI][-meabi=VER][-mthumb][-EB|-EL][-mapcs-32|-mapcs-26|-mapcs-float|-mapcs-reentrant][-mthumb-interwork] [-k]_Target CRIS options:_[-underscore | -no-underscore][-pic] [-N][-emulation=criself | -emulation=crisaout][-march=v0_v10 | -march=v10 | -march=v32 | -march=common_v10_v32]_Target D10V options:_[-O]_Target D30V options:_[-O|-n|-N]_Target H8/300 options:_[-h-tick-hex]_Target i386 options:_[-32|-64] [-n][-march=CPU[+EXTENSION...]] [-mtune=CPU]_Target i960 options:_[-ACA|-ACA_A|-ACB|-ACC|-AKA|-AKB|-AKC|-AMC][-b] [-no-relax]_Target IA-64 options:_[-mconstant-gp|-mauto-pic][-milp32|-milp64|-mlp64|-mp64][-mle|mbe][-mtune=itanium1|-mtune=itanium2][-munwind-check=warning|-munwind-check=error][-mhint.b=ok|-mhint.b=warning|-mhint.b=error][-x|-xexplicit] [-xauto] [-xdebug]_Target IP2K options:_[-mip2022|-mip2022ext]_Target M32C options:_[-m32c|-m16c] [-relax] [-h-tick-hex]_Target M32R options:_[-m32rx|-[no-]warn-explicit-parallel-conflicts|-W[n]p]_Target M680X0 options:_[-l] [-m68000|-m68010|-m68020|...]_Target M68HC11 options:_[-m68hc11|-m68hc12|-m68hcs12][-mshort|-mlong][-mshort-double|-mlong-double][-force-long-branches] [-short-branches][-strict-direct-mode] [-print-insn-syntax][-print-opcodes] [-generate-example]_Target MCORE options:_[-jsri2bsr] [-sifilter] [-relax][-mcpu=[210|340]]_Target MIPS options:_[-nocpp] [-EL] [-EB] [-O[OPTIMIZATION LEVEL]][-g[DEBUG LEVEL]] [-G NUM] [-KPIC] [-call_shared][-non_shared] [-xgot [-mvxworks-pic][-mabi=ABI] [-32] [-n32] [-64] [-mfp32] [-mgp32][-march=CPU] [-mtune=CPU] [-mips1] [-mips2][-mips3] [-mips4] [-mips5] [-mips32] [-mips32r2][-mips64] [-mips64r2][-construct-floats] [-no-construct-floats][-trap] [-no-break] [-break] [-no-trap][-mfix7000] [-mno-fix7000][-mips16] [-no-mips16][-msmartmips] [-mno-smartmips][-mips3d] [-no-mips3d][-mdmx] [-no-mdmx][-mdsp] [-mno-dsp][-mdspr2] [-mno-dspr2][-mmt] [-mno-mt][-mdebug] [-no-mdebug][-mpdr] [-mno-pdr]_Target MMIX options:_[-fixed-special-register-names] [-globalize-symbols][-gnu-syntax] [-relax] [-no-predefined-symbols][-no-expand] [-no-merge-gregs] [-x][-linker-allocated-gregs]_Target PDP11 options:_[-mpic|-mno-pic] [-mall] [-mno-extensions][-mEXTENSION|-mno-EXTENSION][-mCPU] [-mMACHINE]_Target picoJava options:_[-mb|-me]_Target PowerPC options:_[-mpwrx|-mpwr2|-mpwr|-m601|-mppc|-mppc32|-m603|-m604|-m403|-m405|-mppc64|-m620|-mppc64bridge|-mbooke|-mbooke32|-mbooke64][-mcom|-many|-maltivec|-mvsx] [-memb][-mregnames|-mno-regnames][-mrelocatable|-mrelocatable-lib][-mlittle|-mlittle-endian|-mbig|-mbig-endian][-msolaris|-mno-solaris]_Target SPARC options:_[-Av6|-Av7|-Av8|-Asparclet|-Asparclite-Av8plus|-Av8plusa|-Av9|-Av9a][-xarch=v8plus|-xarch=v8plusa] [-bump][-32|-64]_Target TIC54X options:_[-mcpu=54[123589]|-mcpu=54[56]lp] [-mfar-mode|-mf][-merrors-to-file <FILENAME>|-me <FILENAME>]_Target Z80 options:_[-z80] [-r800][ -ignore-undocumented-instructions] [-Wnud][ -ignore-unportable-instructions] [-Wnup][ -warn-undocumented-instructions] [-Wud][ -warn-unportable-instructions] [-Wup][ -forbid-undocumented-instructions] [-Fud][ -forbid-unportable-instructions] [-Fup]_Target Xtensa options:_[-[no-]text-section-literals] [-[no-]absolute-literals][-[no-]target-align] [-[no-]longcalls][-[no-]transform][-rename-section OLDNAME=NEWNAME]`@FILE'Read command-line options from FILE. The options read areinserted in place of the original @FILE option. If FILE does notexist, or cannot be read, then the option will be treatedliterally, and not removed.Options in FILE are separated by whitespace. A whitespacecharacter may be included in an option by surrounding the entireoption in either single or double quotes. Any character(including a backslash) may be included by prefixing the characterto be included with a backslash. The FILE may itself containadditional @FILE options; any such options will be processedrecursively.`-a[cdghlmns]'Turn on listings, in any of a variety of ways:`-ac'omit false conditionals`-ad'omit debugging directives`-ag'include general information, like as version and optionspassed`-ah'include high-level source`-al'include assembly`-am'include macro expansions`-an'omit forms processing`-as'include symbols`=file'set the name of the listing fileYou may combine these options; for example, use `-aln' for assemblylisting without forms processing. The `=file' option, if used,must be the last one. By itself, `-a' defaults to `-ahls'.`--alternate'Begin in alternate macro mode. *Note `.altmacro': Altmacro.`-D'Ignored. This option is accepted for script compatibility withcalls to other assemblers.`--debug-prefix-map OLD=NEW'When assembling files in directory `OLD', record debugginginformation describing them as in `NEW' instead.`--defsym SYM=VALUE'Define the symbol SYM to be VALUE before assembling the input file.VALUE must be an integer constant. As in C, a leading `0x'indicates a hexadecimal value, and a leading `0' indicates an octalvalue. The value of the symbol can be overridden inside a sourcefile via the use of a `.set' pseudo-op.`-f'"fast"--skip whitespace and comment preprocessing (assume source iscompiler output).`-g'`--gen-debug'Generate debugging information for each assembler source lineusing whichever debug format is preferred by the target. Thiscurrently means either STABS, ECOFF or DWARF2.`--gstabs'Generate stabs debugging information for each assembler line. Thismay help debugging assembler code, if the debugger can handle it.`--gstabs+'Generate stabs debugging information for each assembler line, withGNU extensions that probably only gdb can handle, and that couldmake other debuggers crash or refuse to read your program. Thismay help debugging assembler code. Currently the only GNUextension is the location of the current working directory atassembling time.`--gdwarf-2'Generate DWARF2 debugging information for each assembler line.This may help debugging assembler code, if the debugger can handleit. Note--this option is only supported by some targets, not allof them.`--help'Print a summary of the command line options and exit.`--target-help'Print a summary of all target specific options and exit.`-I DIR'Add directory DIR to the search list for `.include' directives.`-J'Don't warn about signed overflow.`-K'Issue warnings when difference tables altered for longdisplacements.`-L'`--keep-locals'Keep (in the symbol table) local symbols. These symbols start withsystem-specific local label prefixes, typically `.L' for ELFsystems or `L' for traditional a.out systems. *Note SymbolNames::.`--listing-lhs-width=NUMBER'Set the maximum width, in words, of the output data column for anassembler listing to NUMBER.`--listing-lhs-width2=NUMBER'Set the maximum width, in words, of the output data column forcontinuation lines in an assembler listing to NUMBER.`--listing-rhs-width=NUMBER'Set the maximum width of an input source line, as displayed in alisting, to NUMBER bytes.`--listing-cont-lines=NUMBER'Set the maximum number of lines printed in a listing for a singleline of input to NUMBER + 1.`-o OBJFILE'Name the object-file output from `as' OBJFILE.`-R'Fold the data section into the text section.Set the default size of GAS's hash tables to a prime number closeto NUMBER. Increasing this value can reduce the length of time ittakes the assembler to perform its tasks, at the expense ofincreasing the assembler's memory requirements. Similarlyreducing this value can reduce the memory requirements at theexpense of speed.`--reduce-memory-overheads'This option reduces GAS's memory requirements, at the expense ofmaking the assembly processes slower. Currently this switch is asynonym for `--hash-size=4051', but in the future it may haveother effects as well.`--statistics'Print the maximum space (in bytes) and total time (in seconds)used by assembly.`--strip-local-absolute'Remove local absolute symbols from the outgoing symbol table.`-v'`-version'Print the `as' version.`--version'Print the `as' version and exit.`-W'`--no-warn'Suppress warning messages.`--fatal-warnings'Treat warnings as errors.`--warn'Don't suppress warning messages or treat them as errors.`-w'Ignored.`-x'Ignored.`-Z'Generate an object file even after errors.`-- | FILES ...'Standard input, or source files to assemble.The following options are available when as is configured for an ARCprocessor.`-marc[5|6|7|8]'This option selects the core processor variant.`-EB | -EL'Select either big-endian (-EB) or little-endian (-EL) output.The following options are available when as is configured for the ARMprocessor family.`-mcpu=PROCESSOR[+EXTENSION...]'Specify which ARM processor variant is the target.`-march=ARCHITECTURE[+EXTENSION...]'Specify which ARM architecture variant is used by the target.`-mfpu=FLOATING-POINT-FORMAT'Select which Floating Point architecture is the target.`-mfloat-abi=ABI'Select which floating point ABI is in use.`-mthumb'Enable Thumb only instruction decoding.`-mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant'Select which procedure calling convention is in use.`-EB | -EL'Select either big-endian (-EB) or little-endian (-EL) output.`-mthumb-interwork'Specify that the code has been generated with interworking betweenThumb and ARM code in mind.`-k'Specify that PIC code has been generated.See the info pages for documentation of the CRIS-specific options.The following options are available when as is configured for a D10Vprocessor.`-O'Optimize output by parallelizing instructions.The following options are available when as is configured for a D30Vprocessor.`-O'Optimize output by parallelizing instructions.`-n'Warn when nops are generated.`-N'Warn when a nop after a 32-bit multiply instruction is generated.The following options are available when as is configured for theIntel 80960 processor.`-ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC'Specify which variant of the 960 architecture is the target.`-b'Add code to collect statistics about branches taken.`-no-relax'Do not alter compare-and-branch instructions for longdisplacements; error if necessary.The following options are available when as is configured for theUbicom IP2K series.`-mip2022ext'Specifies that the extended IP2022 instructions are allowed.`-mip2022'Restores the default behaviour, which restricts the permittedinstructions to just the basic IP2022 ones.The following options are available when as is configured for theRenesas M32C and M16C processors.`-m32c'Assemble M32C instructions.`-m16c'Assemble M16C instructions (the default).`-relax'Enable support for link-time relaxations.`-h-tick-hex'Support H'00 style hex constants in addition to 0x00 style.The following options are available when as is configured for theRenesas M32R (formerly Mitsubishi M32R) series.`--m32rx'Specify which processor in the M32R family is the target. Thedefault is normally the M32R, but this option changes it to theM32RX.`--warn-explicit-parallel-conflicts or --Wp'Produce warning messages when questionable parallel constructs areencountered.`--no-warn-explicit-parallel-conflicts or --Wnp'Do not produce warning messages when questionable parallelconstructs are encountered.The following options are available when as is configured for theMotorola 68000 series.`-l'Shorten references to undefined symbols, to one word instead oftwo.`-m68000 | -m68008 | -m68010 | -m68020 | -m68030'`| -m68040 | -m68060 | -m68302 | -m68331 | -m68332'`| -m68333 | -m68340 | -mcpu32 | -m5200'Specify what processor in the 68000 family is the target. Thedefault is normally the 68020, but this can be changed atconfiguration time.`-m68881 | -m68882 | -mno-68881 | -mno-68882'The target machine does (or does not) have a floating-pointcoprocessor. The default is to assume a coprocessor for 68020,68030, and cpu32. Although the basic 68000 is not compatible withthe 68881, a combination of the two can be specified, since it'spossible to do emulation of the coprocessor instructions with themain processor.`-m68851 | -mno-68851'The target machine does (or does not) have a memory-managementunit coprocessor. The default is to assume an MMU for 68020 andup.For details about the PDP-11 machine dependent features options, see*Note PDP-11-Options::.`-mpic | -mno-pic'Generate position-independent (or position-dependent) code. Thedefault is `-mpic'.`-mall'`-mall-extensions'Enable all instruction set extensions. This is the default.`-mno-extensions'Disable all instruction set extensions.`-mEXTENSION | -mno-EXTENSION'Enable (or disable) a particular instruction set extension.`-mCPU'Enable the instruction set extensions supported by a particularCPU, and disable all other extensions.`-mMACHINE'Enable the instruction set extensions supported by a particularmachine model, and disable all other extensions.The following options are available when as is configured for apicoJava processor.`-mb'Generate "big endian" format output.`-ml'Generate "little endian" format output.The following options are available when as is configured for theMotorola 68HC11 or 68HC12 series.`-m68hc11 | -m68hc12 | -m68hcs12'Specify what processor is the target. The default is defined bythe configuration option when building the assembler.`-mshort'Specify to use the 16-bit integer ABI.`-mlong'Specify to use the 32-bit integer ABI.`-mshort-double'Specify to use the 32-bit double ABI.`-mlong-double'Specify to use the 64-bit double ABI.`--force-long-branches'Relative branches are turned into absolute ones. This concernsconditional branches, unconditional branches and branches to a subroutine.`-S | --short-branches'Do not turn relative branches into absolute ones when the offsetis out of range.`--strict-direct-mode'Do not turn the direct addressing mode into extended addressingmode when the instruction does not support direct addressing mode.`--print-insn-syntax'Print the syntax of instruction in case of error.`--print-opcodes'print the list of instructions with syntax and then exit.`--generate-example'print an example of instruction for each possible instruction andthen exit. This option is only useful for testing `as'.The following options are available when `as' is configured for theSPARC architecture:`-Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite'`-Av8plus | -Av8plusa | -Av9 | -Av9a'Explicitly select a variant of the SPARC architecture.`-Av8plus' and `-Av8plusa' select a 32 bit environment. `-Av9'and `-Av9a' select a 64 bit environment.`-Av8plusa' and `-Av9a' enable the SPARC V9 instruction set withUltraSPARC extensions.`-xarch=v8plus | -xarch=v8plusa'For compatibility with the Solaris v9 assembler. These options areequivalent to -Av8plus and -Av8plusa, respectively.`-bump'Warn when the assembler switches to another architecture.The following options are available when as is configured for the'c54x architecture.`-mfar-mode'Enable extended addressing mode. All addresses and relocationswill assume extended addressing (usually 23 bits).`-mcpu=CPU_VERSION'Sets the CPU version being compiled for.`-merrors-to-file FILENAME'Redirect error output to a file, for broken systems which don'tsupport such behaviour in the shell.The following options are available when as is configured for a MIPSprocessor.`-G NUM'This option sets the largest size of an object that can bereferenced implicitly with the `gp' register. It is only acceptedfor targets that use ECOFF format, such as a DECstation runningUltrix. The default value is 8.`-EB'Generate "big endian" format output.`-EL'Generate "little endian" format output.`-mips1'`-mips2'`-mips3'`-mips4'`-mips5'`-mips32'`-mips32r2'`-mips64'`-mips64r2'Generate code for a particular MIPS Instruction Set Architecturelevel. `-mips1' is an alias for `-march=r3000', `-mips2' is analias for `-march=r6000', `-mips3' is an alias for `-march=r4000'and `-mips4' is an alias for `-march=r8000'. `-mips5', `-mips32',`-mips32r2', `-mips64', and `-mips64r2' correspond to generic`MIPS V', `MIPS32', `MIPS32 Release 2', `MIPS64', and `MIPS64Release 2' ISA processors, respectively.`-march=CPU'Generate code for a particular MIPS cpu.`-mtune=CPU'Schedule and tune for a particular MIPS cpu.`-mfix7000'`-mno-fix7000'Cause nops to be inserted if the read of the destination registerof an mfhi or mflo instruction occurs in the following twoinstructions.`-mdebug'`-no-mdebug'Cause stabs-style debugging output to go into an ECOFF-style.mdebug section instead of the standard ELF .stabs sections.`-mpdr'`-mno-pdr'Control generation of `.pdr' sections.`-mgp32'`-mfp32'The register sizes are normally inferred from the ISA and ABI, butthese flags force a certain group of registers to be treated as 32bits wide at all times. `-mgp32' controls the size ofgeneral-purpose registers and `-mfp32' controls the size offloating-point registers.`-mips16'`-no-mips16'Generate code for the MIPS 16 processor. This is equivalent toputting `.set mips16' at the start of the assembly file.`-no-mips16' turns off this option.`-msmartmips'`-mno-smartmips'Enables the SmartMIPS extension to the MIPS32 instruction set.This is equivalent to putting `.set smartmips' at the start of theassembly file. `-mno-smartmips' turns off this option.`-mips3d'`-no-mips3d'Generate code for the MIPS-3D Application Specific Extension.This tells the assembler to accept MIPS-3D instructions.`-no-mips3d' turns off this option.`-mdmx'`-no-mdmx'Generate code for the MDMX Application Specific Extension. Thistells the assembler to accept MDMX instructions. `-no-mdmx' turnsoff this option.`-mdsp'`-mno-dsp'Generate code for the DSP Release 1 Application Specific Extension.This tells the assembler to accept DSP Release 1 instructions.`-mno-dsp' turns off this option.`-mdspr2'`-mno-dspr2'Generate code for the DSP Release 2 Application Specific Extension.This option implies -mdsp. This tells the assembler to accept DSPRelease 2 instructions. `-mno-dspr2' turns off this option.`-mmt'`-mno-mt'Generate code for the MT Application Specific Extension. Thistells the assembler to accept MT instructions. `-mno-mt' turnsoff this option.`--construct-floats'`--no-construct-floats'The `--no-construct-floats' option disables the construction ofdouble width floating point constants by loading the two halves ofthe value into the two single width floating point registers thatmake up the double width register. By default`--construct-floats' is selected, allowing construction of thesefloating point constants.`--emulation=NAME'This option causes `as' to emulate `as' configured for some othertarget, in all respects, including output format (choosing betweenELF and ECOFF only), handling of pseudo-opcodes which may generatedebugging information or store symbol table information, anddefault endianness. The available configuration names are:`mipsecoff', `mipself', `mipslecoff', `mipsbecoff', `mipslelf',`mipsbelf'. The first two do not alter the default endiannessfrom that of the primary target for which the assembler wasconfigured; the others change the default to little- or big-endianas indicated by the `b' or `l' in the name. Using `-EB' or `-EL'will override the endianness selection in any case.This option is currently supported only when the primary target`as' is configured for is a MIPS ELF or ECOFF target.Furthermore, the primary target or others specified with`--enable-targets=...' at configuration time must include supportfor the other format, if both are to be available. For example,the Irix 5 configuration includes support for both.Eventually, this option will support more configurations, with morefine-grained control over the assembler's behavior, and will besupported for more processors.`-nocpp'`as' ignores this option. It is accepted for compatibility withthe native tools.`--trap'`--no-trap'`--break'`--no-break'Control how to deal with multiplication overflow and division byzero. `--trap' or `--no-break' (which are synonyms) take a trapexception (and only work for Instruction Set Architecture level 2and higher); `--break' or `--no-trap' (also synonyms, and thedefault) take a break exception.`-n'When this option is used, `as' will issue a warning every time itgenerates a nop instruction from a macro.The following options are available when as is configured for anMCore processor.`-jsri2bsr'`-nojsri2bsr'Enable or disable the JSRI to BSR transformation. By default thisis enabled. The command line option `-nojsri2bsr' can be used todisable it.`-sifilter'`-nosifilter'Enable or disable the silicon filter behaviour. By default thisis disabled. The default can be overridden by the `-sifilter'command line option.`-relax'Alter jump instructions for long displacements.`-mcpu=[210|340]'Select the cpu type on the target hardware. This controls whichinstructions can be assembled.`-EB'Assemble for a big endian target.`-EL'Assemble for a little endian target.See the info pages for documentation of the MMIX-specific options.The following options are available when as is configured for anXtensa processor.`--text-section-literals | --no-text-section-literals'With `--text-section-literals', literal pools are interspersed inthe text section. The default is `--no-text-section-literals',which places literals in a separate section in the output file.These options only affect literals referenced via PC-relative`L32R' instructions; literals for absolute mode `L32R'instructions are handled separately.`--absolute-literals | --no-absolute-literals'Indicate to the assembler whether `L32R' instructions use absoluteor PC-relative addressing. The default is to assume absoluteaddressing if the Xtensa processor includes the absolute `L32R'addressing option. Otherwise, only the PC-relative `L32R' modecan be used.`--target-align | --no-target-align'Enable or disable automatic alignment to reduce branch penaltiesat the expense of some code density. The default is`--target-align'.`--longcalls | --no-longcalls'Enable or disable transformation of call instructions to allowcalls across a greater range of addresses. The default is`--no-longcalls'.`--transform | --no-transform'Enable or disable all assembler transformations of Xtensainstructions. The default is `--transform'; `--no-transform'should be used only in the rare cases when the instructions mustbe exactly as specified in the assembly source.`--rename-section OLDNAME=NEWNAME'When generating output sections, rename the OLDNAME section toNEWNAME.The following options are available when as is configured for a Z80family processor.`-z80'Assemble for Z80 processor.`-r800'Assemble for R800 processor.`-ignore-undocumented-instructions'`-Wnud'Assemble undocumented Z80 instructions that also work on R800without warning.`-ignore-unportable-instructions'`-Wnup'Assemble all undocumented Z80 instructions without warning.`-warn-undocumented-instructions'`-Wud'Issue a warning for undocumented Z80 instructions that also workon R800.`-warn-unportable-instructions'`-Wup'Issue a warning for undocumented Z80 instructions that do not workon R800.`-forbid-undocumented-instructions'`-Fud'Treat all undocumented instructions as errors.`-forbid-unportable-instructions'`-Fup'Treat undocumented Z80 instructions that do not work on R800 aserrors.* Menu:* Manual:: Structure of this Manual* GNU Assembler:: The GNU Assembler* Object Formats:: Object File Formats* Command Line:: Command Line* Input Files:: Input Files* Object:: Output (Object) File* Errors:: Error and Warning MessagesFile: as.info, Node: Manual, Next: GNU Assembler, Up: Overview1.1 Structure of this Manual============================This manual is intended to describe what you need to know to use GNU`as'. We cover the syntax expected in source files, including notationfor symbols, constants, and expressions; the directives that `as'understands; and of course how to invoke `as'.This manual also describes some of the machine-dependent features ofvarious flavors of the assembler.On the other hand, this manual is _not_ intended as an introductionto programming in assembly language--let alone programming in general!In a similar vein, we make no attempt to introduce the machinearchitecture; we do _not_ describe the instruction set, standardmnemonics, registers or addressing modes that are standard to aparticular architecture. You may want to consult the manufacturer'smachine architecture manual for this information.File: as.info, Node: GNU Assembler, Next: Object Formats, Prev: Manual, Up: Overview1.2 The GNU Assembler=====================GNU `as' is really a family of assemblers. If you use (or have used)the GNU assembler on one architecture, you should find a fairly similarenvironment when you use it on another architecture. Each version hasmuch in common with the others, including object file formats, mostassembler directives (often called "pseudo-ops") and assembler syntax.`as' is primarily intended to assemble the output of the GNU Ccompiler `gcc' for use by the linker `ld'. Nevertheless, we've triedto make `as' assemble correctly everything that other assemblers forthe same machine would assemble. Any exceptions are documentedexplicitly (*note Machine Dependencies::). This doesn't mean `as'always uses the same syntax as another assembler for the samearchitecture; for example, we know of several incompatible versions of680x0 assembly language syntax.Unlike older assemblers, `as' is designed to assemble a sourceprogram in one pass of the source file. This has a subtle impact on the`.org' directive (*note `.org': Org.).File: as.info, Node: Object Formats, Next: Command Line, Prev: GNU Assembler, Up: Overview1.3 Object File Formats=======================The GNU assembler can be configured to produce several alternativeobject file formats. For the most part, this does not affect how youwrite assembly language programs; but directives for debugging symbolsare typically different in different file formats. *Note SymbolAttributes: Symbol Attributes.File: as.info, Node: Command Line, Next: Input Files, Prev: Object Formats, Up: Overview1.4 Command Line================After the program name `as', the command line may contain options andfile names. Options may appear in any order, and may be before, after,or between file names. The order of file names is significant.`--' (two hyphens) by itself names the standard input fileexplicitly, as one of the files for `as' to assemble.Except for `--' any command line argument that begins with a hyphen(`-') is an option. Each option changes the behavior of `as'. Nooption changes the way another option works. An option is a `-'followed by one or more letters; the case of the letter is important.All options are optional.Some options expect exactly one file name to follow them. The filename may either immediately follow the option's letter (compatible witholder assemblers) or it may be the next command argument (GNUstandard). These two command lines are equivalent:as -o my-object-file.o mumble.sas -omy-object-file.o mumble.sFile: as.info, Node: Input Files, Next: Object, Prev: Command Line, Up: Overview1.5 Input Files===============We use the phrase "source program", abbreviated "source", to describethe program input to one run of `as'. The program may be in one ormore files; how the source is partitioned into files doesn't change themeaning of the source.The source program is a concatenation of the text in all the files,in the order specified.Each time you run `as' it assembles exactly one source program. Thesource program is made up of one or more files. (The standard input isalso a file.)You give `as' a command line that has zero or more input file names.The input files are read (from left file name to right). A commandline argument (in any position) that has no special meaning is taken tobe an input file name.If you give `as' no file names it attempts to read one input filefrom the `as' standard input, which is normally your terminal. You mayhave to type <ctl-D> to tell `as' there is no more program to assemble.Use `--' if you need to explicitly name the standard input file inyour command line.If the source is empty, `as' produces a small, empty object file.Filenames and Line-numbers--------------------------There are two ways of locating a line in the input file (or files) andeither may be used in reporting error messages. One way refers to aline number in a physical file; the other refers to a line number in a"logical" file. *Note Error and Warning Messages: Errors."Physical files" are those files named in the command line given to`as'."Logical files" are simply names declared explicitly by assemblerdirectives; they bear no relation to physical files. Logical filenames help error messages reflect the original source file, when `as'source is itself synthesized from other files. `as' understands the`#' directives emitted by the `gcc' preprocessor. See also *Note`.file': File.File: as.info, Node: Object, Next: Errors, Prev: Input Files, Up: Overview1.6 Output (Object) File========================Every time you run `as' it produces an output file, which is yourassembly language program translated into numbers. This file is theobject file. Its default name is `a.out'. You can give it anothername by using the `-o' option. Conventionally, object file names endwith `.o'. The default name is used for historical reasons: olderassemblers were capable of assembling self-contained programs directlyinto a runnable program. (For some formats, this isn't currentlypossible, but it can be done for the `a.out' format.)The object file is meant for input to the linker `ld'. It containsassembled program code, information to help `ld' integrate theassembled program into a runnable file, and (optionally) symbolicinformation for the debugger.File: as.info, Node: Errors, Prev: Object, Up: Overview1.7 Error and Warning Messages==============================`as' may write warnings and error messages to the standard error file(usually your terminal). This should not happen when a compiler runs`as' automatically. Warnings report an assumption made so that `as'could keep assembling a flawed program; errors report a grave problemthat stops the assembly.Warning messages have the formatfile_name:NNN:Warning Message Text(where NNN is a line number). If a logical file name has been given(*note `.file': File.) it is used for the filename, otherwise the nameof the current input file is used. If a logical line number was given(*note `.line': Line.) then it is used to calculate the number printed,otherwise the actual line in the current source file is printed. Themessage text is intended to be self explanatory (in the grand Unixtradition).Error messages have the formatfile_name:NNN:FATAL:Error Message TextThe file name and line number are derived as for warning messages.The actual message text may be rather less explanatory because many ofthem aren't supposed to happen.File: as.info, Node: Invoking, Next: Syntax, Prev: Overview, Up: Top2 Command-Line Options**********************This chapter describes command-line options available in _all_ versionsof the GNU assembler; see *Note Machine Dependencies::, for optionsspecific to particular machine architectures.If you are invoking `as' via the GNU C compiler, you can use the`-Wa' option to pass arguments through to the assembler. The assemblerarguments must be separated from each other (and the `-Wa') by commas.For example:gcc -c -g -O -Wa,-alh,-L file.cThis passes two options to the assembler: `-alh' (emit a listing tostandard output with high-level and assembly source) and `-L' (retainlocal symbols in the symbol table).Usually you do not need to use this `-Wa' mechanism, since manycompiler command-line options are automatically passed to the assemblerby the compiler. (You can call the GNU compiler driver with the `-v'option to see precisely what options it passes to each compilationpass, including the assembler.)* Menu:* a:: -a[cdghlns] enable listings* alternate:: --alternate enable alternate macro syntax* D:: -D for compatibility* f:: -f to work faster* I:: -I for .include search path* K:: -K for difference tables* L:: -L to retain local symbols* listing:: --listing-XXX to configure listing output* M:: -M or --mri to assemble in MRI compatibility mode* MD:: --MD for dependency tracking* o:: -o to name the object file* R:: -R to join data and text sections* statistics:: --statistics to see statistics about assembly* traditional-format:: --traditional-format for compatible output* v:: -v to announce version* W:: -W, --no-warn, --warn, --fatal-warnings to control warnings* Z:: -Z to make object file even after errorsFile: as.info, Node: a, Next: alternate, Up: Invoking2.1 Enable Listings: `-a[cdghlns]'==================================These options enable listing output from the assembler. By itself,`-a' requests high-level, assembly, and symbols listing. You can useother letters to select specific options for the list: `-ah' requests ahigh-level language listing, `-al' requests an output-program assemblylisting, and `-as' requests a symbol table listing. High-levellistings require that a compiler debugging option like `-g' be used,and that assembly listings (`-al') be requested also.Use the `-ag' option to print a first section with general assemblyinformation, like as version, switches passed, or time stamp.Use the `-ac' option to omit false conditionals from a listing. Anylines which are not assembled because of a false `.if' (or `.ifdef', orany other conditional), or a true `.if' followed by an `.else', will beomitted from the listing.Use the `-ad' option to omit debugging directives from the listing.Once you have specified one of these options, you can further controllisting output and its appearance using the directives `.list',`.nolist', `.psize', `.eject', `.title', and `.sbttl'. The `-an'option turns off all forms processing. If you do not request listingoutput with one of the `-a' options, the listing-control directiveshave no effect.The letters after `-a' may be combined into one option, _e.g._,`-aln'.Note if the assembler source is coming from the standard input (e.g.,because it is being created by `gcc' and the `-pipe' command line switchis being used) then the listing will not contain any comments orpreprocessor directives. This is because the listing code buffersinput source lines from stdin only after they have been preprocessed bythe assembler. This reduces memory usage and makes the code moreefficient.File: as.info, Node: alternate, Next: D, Prev: a, Up: Invoking2.2 `--alternate'=================Begin in alternate macro mode, see *Note `.altmacro': Altmacro.File: as.info, Node: D, Next: f, Prev: alternate, Up: Invoking2.3 `-D'========This option has no effect whatsoever, but it is accepted to make it morelikely that scripts written for other assemblers also work with `as'.File: as.info, Node: f, Next: I, Prev: D, Up: Invoking2.4 Work Faster: `-f'=====================`-f' should only be used when assembling programs written by a(trusted) compiler. `-f' stops the assembler from doing whitespace andcomment preprocessing on the input file(s) before assembling them.*Note Preprocessing: Preprocessing._Warning:_ if you use `-f' when the files actually need to bepreprocessed (if they contain comments, for example), `as' doesnot work correctly.File: as.info, Node: I, Next: K, Prev: f, Up: Invoking2.5 `.include' Search Path: `-I' PATH=====================================Use this option to add a PATH to the list of directories `as' searchesfor files specified in `.include' directives (*note `.include':Include.). You may use `-I' as many times as necessary to include avariety of paths. The current working directory is always searchedfirst; after that, `as' searches any `-I' directories in the same orderas they were specified (left to right) on the command line.File: as.info, Node: K, Next: L, Prev: I, Up: Invoking2.6 Difference Tables: `-K'===========================`as' sometimes alters the code emitted for directives of the form`.word SYM1-SYM2'. *Note `.word': Word. You can use the `-K' optionif you want a warning issued when this is done.File: as.info, Node: L, Next: listing, Prev: K, Up: Invoking2.7 Include Local Symbols: `-L'===============================Symbols beginning with system-specific local label prefixes, typically`.L' for ELF systems or `L' for traditional a.out systems, are called"local symbols". *Note Symbol Names::. Normally you do not see suchsymbols when debugging, because they are intended for the use ofprograms (like compilers) that compose assembler programs, not for yournotice. Normally both `as' and `ld' discard such symbols, so you donot normally debug with them.This option tells `as' to retain those local symbols in the objectfile. Usually if you do this you also tell the linker `ld' to preservethose symbols.File: as.info, Node: listing, Next: M, Prev: L, Up: Invoking2.8 Configuring listing output: `--listing'===========================================The listing feature of the assembler can be enabled via the commandline switch `-a' (*note a::). This feature combines the input sourcefile(s) with a hex dump of the corresponding locations in the outputobject file, and displays them as a listing file. The format of thislisting can be controlled by directives inside the assembler source(i.e., `.list' (*note List::), `.title' (*note Title::), `.sbttl'(*note Sbttl::), `.psize' (*note Psize::), and `.eject' (*note Eject::)and also by the following switches:`--listing-lhs-width=`number''Sets the maximum width, in words, of the first line of the hexbyte dump. This dump appears on the left hand side of the listingoutput.`--listing-lhs-width2=`number''Sets the maximum width, in words, of any further lines of the hexbyte dump for a given input source line. If this value is notspecified, it defaults to being the same as the value specifiedfor `--listing-lhs-width'. If neither switch is used the defaultis to one.`--listing-rhs-width=`number''Sets the maximum width, in characters, of the source line that isdisplayed alongside the hex dump. The default value for thisparameter is 100. The source line is displayed on the right handside of the listing output.`--listing-cont-lines=`number''Sets the maximum number of continuation lines of hex dump thatwill be displayed for a given single line of source input. Thedefault value is 4.File: as.info, Node: M, Next: MD, Prev: listing, Up: Invoking2.9 Assemble in MRI Compatibility Mode: `-M'============================================The `-M' or `--mri' option selects MRI compatibility mode. Thischanges the syntax and pseudo-op handling of `as' to make it compatiblewith the `ASM68K' or the `ASM960' (depending upon the configuredtarget) assembler from Microtec Research. The exact nature of the MRIsyntax will not be documented here; see the MRI manuals for moreinformation. Note in particular that the handling of macros and macroarguments is somewhat different. The purpose of this option is topermit assembling existing MRI assembler code using `as'.The MRI compatibility is not complete. Certain operations of theMRI assembler depend upon its object file format, and can not besupported using other object file formats. Supporting these wouldrequire enhancing each object file format individually. These are:* global symbols in common sectionThe m68k MRI assembler supports common sections which are mergedby the linker. Other object file formats do not support this.`as' handles common sections by treating them as a single commonsymbol. It permits local symbols to be defined within a commonsection, but it can not support global symbols, since it has noway to describe them.* complex relocationsThe MRI assemblers support relocations against a negated sectionaddress, and relocations which combine the start addresses of twoor more sections. These are not support by other object fileformats.* `END' pseudo-op specifying start addressThe MRI `END' pseudo-op permits the specification of a startaddress. This is not supported by other object file formats. Thestart address may instead be specified using the `-e' option tothe linker, or in a linker script.* `IDNT', `.ident' and `NAME' pseudo-opsThe MRI `IDNT', `.ident' and `NAME' pseudo-ops assign a modulename to the output file. This is not supported by other objectfile formats.* `ORG' pseudo-opThe m68k MRI `ORG' pseudo-op begins an absolute section at a givenaddress. This differs from the usual `as' `.org' pseudo-op, whichchanges the location within the current section. Absolutesections are not supported by other object file formats. Theaddress of a section may be assigned within a linker script.There are some other features of the MRI assembler which are notsupported by `as', typically either because they are difficult orbecause they seem of little consequence. Some of these may besupported in future releases.* EBCDIC stringsEBCDIC strings are not supported.* packed binary coded decimalPacked binary coded decimal is not supported. This means that the`DC.P' and `DCB.P' pseudo-ops are not supported.* `FEQU' pseudo-opThe m68k `FEQU' pseudo-op is not supported.* `NOOBJ' pseudo-opThe m68k `NOOBJ' pseudo-op is not supported.* `OPT' branch control optionsThe m68k `OPT' branch control options--`B', `BRS', `BRB', `BRL',and `BRW'--are ignored. `as' automatically relaxes all branches,whether forward or backward, to an appropriate size, so theseoptions serve no purpose.* `OPT' list control optionsThe following m68k `OPT' list control options are ignored: `C',`CEX', `CL', `CRE', `E', `G', `I', `M', `MEX', `MC', `MD', `X'.* other `OPT' optionsThe following m68k `OPT' options are ignored: `NEST', `O', `OLD',`OP', `P', `PCO', `PCR', `PCS', `R'.* `OPT' `D' option is defaultThe m68k `OPT' `D' option is the default, unlike the MRI assembler.`OPT NOD' may be used to turn it off.* `XREF' pseudo-op.The m68k `XREF' pseudo-op is ignored.* `.debug' pseudo-opThe i960 `.debug' pseudo-op is not supported.* `.extended' pseudo-opThe i960 `.extended' pseudo-op is not supported.* `.list' pseudo-op.The various options of the i960 `.list' pseudo-op are notsupported.* `.optimize' pseudo-opThe i960 `.optimize' pseudo-op is not supported.* `.output' pseudo-opThe i960 `.output' pseudo-op is not supported.* `.setreal' pseudo-opThe i960 `.setreal' pseudo-op is not supported.File: as.info, Node: MD, Next: o, Prev: M, Up: Invoking2.10 Dependency Tracking: `--MD'================================`as' can generate a dependency file for the file it creates. This fileconsists of a single rule suitable for `make' describing thedependencies of the main source file.The rule is written to the file named in its argument.This feature is used in the automatic updating of makefiles.File: as.info, Node: o, Next: R, Prev: MD, Up: Invoking2.11 Name the Object File: `-o'===============================There is always one object file output when you run `as'. By defaultit has the name `a.out' (or `b.out', for Intel 960 targets only). Youuse this option (which takes exactly one filename) to give the objectfile a different name.Whatever the object file is called, `as' overwrites any existingfile of the same name.File: as.info, Node: R, Next: statistics, Prev: o, Up: Invoking2.12 Join Data and Text Sections: `-R'======================================`-R' tells `as' to write the object file as if all data-section datalives in the text section. This is only done at the very last moment:your binary data are the same, but data section parts are relocateddifferently. The data section part of your object file is zero byteslong because all its bytes are appended to the text section. (*NoteSections and Relocation: Sections.)When you specify `-R' it would be possible to generate shorteraddress displacements (because we do not have to cross between text anddata section). We refrain from doing this simply for compatibility witholder versions of `as'. In future, `-R' may work this way.When `as' is configured for COFF or ELF output, this option is onlyuseful if you use sections named `.text' and `.data'.`-R' is not supported for any of the HPPA targets. Using `-R'generates a warning from `as'.File: as.info, Node: statistics, Next: traditional-format, Prev: R, Up: Invoking2.13 Display Assembly Statistics: `--statistics'================================================Use `--statistics' to display two statistics about the resources used by`as': the maximum amount of space allocated during the assembly (inbytes), and the total execution time taken for the assembly (in CPUseconds).File: as.info, Node: traditional-format, Next: v, Prev: statistics, Up: Invoking2.14 Compatible Output: `--traditional-format'==============================================For some targets, the output of `as' is different in some ways from theoutput of some existing assembler. This switch requests `as' to usethe traditional format instead.For example, it disables the exception frame optimizations which`as' normally does by default on `gcc' output.File: as.info, Node: v, Next: W, Prev: traditional-format, Up: Invoking2.15 Announce Version: `-v'===========================You can find out what version of as is running by including the option`-v' (which you can also spell as `-version') on the command line.File: as.info, Node: W, Next: Z, Prev: v, Up: Invoking2.16 Control Warnings: `-W', `--warn', `--no-warn', `--fatal-warnings'======================================================================`as' should never give a warning or error message when assemblingcompiler output. But programs written by people often cause `as' togive a warning that a particular assumption was made. All suchwarnings are directed to the standard error file.If you use the `-W' and `--no-warn' options, no warnings are issued.This only affects the warning messages: it does not change anyparticular of how `as' assembles your file. Errors, which stop theassembly, are still reported.If you use the `--fatal-warnings' option, `as' considers files thatgenerate warnings to be in error.You can switch these options off again by specifying `--warn', whichcauses warnings to be output as usual.File: as.info, Node: Z, Prev: W, Up: Invoking2.17 Generate Object File in Spite of Errors: `-Z'==================================================After an error message, `as' normally produces no output. If for somereason you are interested in object file output even after `as' givesan error message on your program, use the `-Z' option. If there areany errors, `as' continues anyways, and writes an object file after afinal warning message of the form `N errors, M warnings, generating badobject file.'File: as.info, Node: Syntax, Next: Sections, Prev: Invoking, Up: Top3 Syntax********This chapter describes the machine-independent syntax allowed in asource file. `as' syntax is similar to what many other assemblers use;it is inspired by the BSD 4.2 assembler, except that `as' does notassemble Vax bit-fields.* Menu:* Preprocessing:: Preprocessing* Whitespace:: Whitespace* Comments:: Comments* Symbol Intro:: Symbols* Statements:: Statements* Constants:: ConstantsFile: as.info, Node: Preprocessing, Next: Whitespace, Up: Syntax3.1 Preprocessing=================The `as' internal preprocessor:* adjusts and removes extra whitespace. It leaves one space or tabbefore the keywords on a line, and turns any other whitespace onthe line into a single space.* removes all comments, replacing them with a single space, or anappropriate number of newlines.* converts character constants into the appropriate numeric values.It does not do macro processing, include file handling, or anythingelse you may get from your C compiler's preprocessor. You can doinclude file processing with the `.include' directive (*note`.include': Include.). You can use the GNU C compiler driver to getother "CPP" style preprocessing by giving the input file a `.S' suffix.*Note Options Controlling the Kind of Output: (gcc.info)OverallOptions.Excess whitespace, comments, and character constants cannot be usedin the portions of the input text that are not preprocessed.If the first line of an input file is `#NO_APP' or if you use the`-f' option, whitespace and comments are not removed from the inputfile. Within an input file, you can ask for whitespace and commentremoval in specific portions of the by putting a line that says `#APP'before the text that may contain whitespace or comments, and putting aline that says `#NO_APP' after this text. This feature is mainlyintend to support `asm' statements in compilers whose output isotherwise free of comments and whitespace.File: as.info, Node: Whitespace, Next: Comments, Prev: Preprocessing, Up: Syntax3.2 Whitespace=============="Whitespace" is one or more blanks or tabs, in any order. Whitespaceis used to separate symbols, and to make programs neater for people toread. Unless within character constants (*note Character Constants:Characters.), any whitespace means the same as exactly one space.File: as.info, Node: Comments, Next: Symbol Intro, Prev: Whitespace, Up: Syntax3.3 Comments============There are two ways of rendering comments to `as'. In both cases thecomment is equivalent to one space.Anything from `/*' through the next `*/' is a comment. This meansyou may not nest these comments./*The only way to include a newline ('\n') in a commentis to use this sort of comment.*//* This sort of comment does not nest. */Anything from the "line comment" character to the next newline isconsidered a comment and is ignored. The line comment character is `;'on the ARC; `@' on the ARM; `;' for the H8/300 family; `;' for the HPPA;`#' on the i386 and x86-64; `#' on the i960; `;' for the PDP-11; `;'for picoJava; `#' for Motorola PowerPC; `!' for the Renesas / SuperH SH;`!' on the SPARC; `#' on the ip2k; `#' on the m32c; `#' on the m32r;`|' on the 680x0; `#' on the 68HC11 and 68HC12; `#' on the Vax; `;' forthe Z80; `!' for the Z8000; `#' on the V850; `#' for Xtensa systems;see *Note Machine Dependencies::.On some machines there are two different line comment characters.One character only begins a comment if it is the first non-whitespacecharacter on a line, while the other always begins a comment.The V850 assembler also supports a double dash as starting a commentthat extends to the end of the line.`--';To be compatible with past assemblers, lines that begin with `#'have a special interpretation. Following the `#' should be an absoluteexpression (*note Expressions::): the logical line number of the _next_line. Then a string (*note Strings: Strings.) is allowed: if presentit is a new logical file name. The rest of the line, if any, should bewhitespace.If the first non-whitespace characters on the line are not numeric,the line is ignored. (Just like a comment.)# This is an ordinary comment.# 42-6 "new_file_name" # New logical file name# This is logical line # 36.This feature is deprecated, and may disappear from future versionsof `as'.File: as.info, Node: Symbol Intro, Next: Statements, Prev: Comments, Up: Syntax3.4 Symbols===========A "symbol" is one or more characters chosen from the set of all letters(both upper and lower case), digits and the three characters `_.$'. Onmost machines, you can also use `$' in symbol names; exceptions arenoted in *Note Machine Dependencies::. No symbol may begin with adigit. Case is significant. There is no length limit: all charactersare significant. Symbols are delimited by characters not in that set,or by the beginning of a file (since the source program must end with anewline, the end of a file is not a possible symbol delimiter). *NoteSymbols::.File: as.info, Node: Statements, Next: Constants, Prev: Symbol Intro, Up: Syntax3.5 Statements==============A "statement" ends at a newline character (`\n') or line separatorcharacter. (The line separator is usually `;', unless this conflictswith the comment character; see *Note Machine Dependencies::.) Thenewline or separator character is considered part of the precedingstatement. Newlines and separators within character constants are anexception: they do not end statements.It is an error to end any statement with end-of-file: the lastcharacter of any input file should be a newline.An empty statement is allowed, and may include whitespace. It isignored.A statement begins with zero or more labels, optionally followed by akey symbol which determines what kind of statement it is. The keysymbol determines the syntax of the rest of the statement. If thesymbol begins with a dot `.' then the statement is an assemblerdirective: typically valid for any computer. If the symbol begins witha letter the statement is an assembly language "instruction": itassembles into a machine language instruction. Different versions of`as' for different computers recognize different instructions. Infact, the same symbol may represent a different instruction in adifferent computer's assembly language.A label is a symbol immediately followed by a colon (`:').Whitespace before a label or after a colon is permitted, but you may nothave whitespace between a label's symbol and its colon. *Note Labels::.For HPPA targets, labels need not be immediately followed by acolon, but the definition of a label must begin in column zero. Thisalso implies that only one label may be defined on each line.label: .directive followed by somethinganother_label: # This is an empty statement.instruction operand_1, operand_2, ...File: as.info, Node: Constants, Prev: Statements, Up: Syntax3.6 Constants=============A constant is a number, written so that its value is known byinspection, without knowing any context. Like this:.byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value..ascii "Ring the bell\7" # A string constant..octa 0x123456789abcdef0123456789ABCDEF0 # A bignum..float 0f-314159265358979323846264338327\95028841971.693993751E-40 # - pi, a flonum.* Menu:* Characters:: Character Constants* Numbers:: Number ConstantsFile: as.info, Node: Characters, Next: Numbers, Up: Constants3.6.1 Character Constants-------------------------There are two kinds of character constants. A "character" stands forone character in one byte and its value may be used in numericexpressions. String constants (properly called string _literals_) arepotentially many bytes and their values may not be used in arithmeticexpressions.* Menu:* Strings:: Strings* Chars:: CharactersFile: as.info, Node: Strings, Next: Chars, Up: Characters3.6.1.1 Strings...............A "string" is written between double-quotes. It may containdouble-quotes or null characters. The way to get special charactersinto a string is to "escape" these characters: precede them with abackslash `\' character. For example `\\' represents one backslash:the first `\' is an escape which tells `as' to interpret the secondcharacter literally as a backslash (which prevents `as' fromrecognizing the second `\' as an escape character). The complete listof escapes follows.`\b'Mnemonic for backspace; for ASCII this is octal code 010.`\f'Mnemonic for FormFeed; for ASCII this is octal code 014.`\n'Mnemonic for newline; for ASCII this is octal code 012.`\r'Mnemonic for carriage-Return; for ASCII this is octal code 015.`\t'Mnemonic for horizontal Tab; for ASCII this is octal code 011.`\ DIGIT DIGIT DIGIT'An octal character code. The numeric code is 3 octal digits. Forcompatibility with other Unix systems, 8 and 9 are accepted asdigits: for example, `\008' has the value 010, and `\009' thevalue 011.`\`x' HEX-DIGITS...'A hex character code. All trailing hex digits are combined.Either upper or lower case `x' works.`\\'Represents one `\' character.`\"'Represents one `"' character. Needed in strings to represent thischaracter, because an unescaped `"' would end the string.`\ ANYTHING-ELSE'Any other character when escaped by `\' gives a warning, butassembles as if the `\' was not present. The idea is that if youused an escape sequence you clearly didn't want the literalinterpretation of the following character. However `as' has noother interpretation, so `as' knows it is giving you the wrongcode and warns you of the fact.Which characters are escapable, and what those escapes represent,varies widely among assemblers. The current set is what we think theBSD 4.2 assembler recognizes, and is a subset of what most C compilersrecognize. If you are in doubt, do not use an escape sequence.File: as.info, Node: Chars, Prev: Strings, Up: Characters3.6.1.2 Characters..................A single character may be written as a single quote immediatelyfollowed by that character. The same escapes apply to characters as tostrings. So if you want to write the character backslash, you mustwrite `'\\' where the first `\' escapes the second `\'. As you cansee, the quote is an acute accent, not a grave accent. A newlineimmediately following an acute accent is taken as a literal characterand does not count as the end of a statement. The value of a characterconstant in a numeric expression is the machine's byte-wide code forthat character. `as' assumes your character code is ASCII: `'A' means65, `'B' means 66, and so on.File: as.info, Node: Numbers, Prev: Characters, Up: Constants3.6.2 Number Constants----------------------`as' distinguishes three kinds of numbers according to how they arestored in the target machine. _Integers_ are numbers that would fitinto an `int' in the C language. _Bignums_ are integers, but they arestored in more than 32 bits. _Flonums_ are floating point numbers,described below.* Menu:* Integers:: Integers* Bignums:: Bignums* Flonums:: FlonumsFile: as.info, Node: Integers, Next: Bignums, Up: Numbers3.6.2.1 Integers................A binary integer is `0b' or `0B' followed by zero or more of the binarydigits `01'.An octal integer is `0' followed by zero or more of the octal digits(`01234567').A decimal integer starts with a non-zero digit followed by zero ormore digits (`0123456789').A hexadecimal integer is `0x' or `0X' followed by one or morehexadecimal digits chosen from `0123456789abcdefABCDEF'.Integers have the usual values. To denote a negative integer, usethe prefix operator `-' discussed under expressions (*note PrefixOperators: Prefix Ops.).File: as.info, Node: Bignums, Next: Flonums, Prev: Integers, Up: Numbers3.6.2.2 Bignums...............A "bignum" has the same syntax and semantics as an integer except thatthe number (or its negative) takes more than 32 bits to represent inbinary. The distinction is made because in some places integers arepermitted while bignums are not.File: as.info, Node: Flonums, Prev: Bignums, Up: Numbers3.6.2.3 Flonums...............A "flonum" represents a floating point number. The translation isindirect: a decimal floating point number from the text is converted by`as' to a generic binary floating point number of more than sufficientprecision. This generic floating point number is converted to aparticular computer's floating point format (or formats) by a portionof `as' specialized to that computer.A flonum is written by writing (in order)* The digit `0'. (`0' is optional on the HPPA.)* A letter, to tell `as' the rest of the number is a flonum. `e' isrecommended. Case is not important.On the H8/300, Renesas / SuperH SH, and AMD 29K architectures, theletter must be one of the letters `DFPRSX' (in upper or lowercase).On the ARC, the letter must be one of the letters `DFRS' (in upperor lower case).On the Intel 960 architecture, the letter must be one of theletters `DFT' (in upper or lower case).On the HPPA architecture, the letter must be `E' (upper case only).* An optional sign: either `+' or `-'.* An optional "integer part": zero or more decimal digits.* An optional "fractional part": `.' followed by zero or moredecimal digits.* An optional exponent, consisting of:* An `E' or `e'.* Optional sign: either `+' or `-'.* One or more decimal digits.At least one of the integer part or the fractional part must bepresent. The floating point number has the usual base-10 value.`as' does all processing using integers. Flonums are computedindependently of any floating point hardware in the computer running`as'.File: as.info, Node: Sections, Next: Symbols, Prev: Syntax, Up: Top4 Sections and Relocation************************** Menu:* Secs Background:: Background* Ld Sections:: Linker Sections* As Sections:: Assembler Internal Sections* Sub-Sections:: Sub-Sections* bss:: bss SectionFile: as.info, Node: Secs Background, Next: Ld Sections, Up: Sections4.1 Background==============Roughly, a section is a range of addresses, with no gaps; all data "in"those addresses is treated the same for some particular purpose. Forexample there may be a "read only" section.The linker `ld' reads many object files (partial programs) andcombines their contents to form a runnable program. When `as' emits anobject file, the partial program is assumed to start at address 0.`ld' assigns the final addresses for the partial program, so thatdifferent partial programs do not overlap. This is actually anoversimplification, but it suffices to explain how `as' uses sections.`ld' moves blocks of bytes of your program to their run-timeaddresses. These blocks slide to their run-time addresses as rigidunits; their length does not change and neither does the order of byteswithin them. Such a rigid unit is called a _section_. Assigningrun-time addresses to sections is called "relocation". It includes thetask of adjusting mentions of object-file addresses so they refer tothe proper run-time addresses. For the H8/300, and for the Renesas /SuperH SH, `as' pads sections if needed to ensure they end on a word(sixteen bit) boundary.An object file written by `as' has at least three sections, any ofwhich may be empty. These are named "text", "data" and "bss" sections.When it generates COFF or ELF output, `as' can also generatewhatever other named sections you specify using the `.section'directive (*note `.section': Section.). If you do not use anydirectives that place output in the `.text' or `.data' sections, thesesections still exist, but are empty.When `as' generates SOM or ELF output for the HPPA, `as' can alsogenerate whatever other named sections you specify using the `.space'and `.subspace' directives. See `HP9000 Series 800 Assembly LanguageReference Manual' (HP 92432-90001) for details on the `.space' and`.subspace' assembler directives.Additionally, `as' uses different names for the standard text, data,and bss sections when generating SOM output. Program text is placedinto the `$CODE$' section, data into `$DATA$', and BSS into `$BSS$'.Within the object file, the text section starts at address `0', thedata section follows, and the bss section follows the data section.When generating either SOM or ELF output files on the HPPA, the textsection starts at address `0', the data section at address `0x4000000',and the bss section follows the data section.To let `ld' know which data changes when the sections are relocated,and how to change that data, `as' also writes to the object filedetails of the relocation needed. To perform relocation `ld' mustknow, each time an address in the object file is mentioned:* Where in the object file is the beginning of this reference to anaddress?* How long (in bytes) is this reference?* Which section does the address refer to? What is the numericvalue of(ADDRESS) - (START-ADDRESS OF SECTION)?* Is the reference to an address "Program-Counter relative"?In fact, every address `as' ever uses is expressed as(SECTION) + (OFFSET INTO SECTION)Further, most expressions `as' computes have this section-relativenature. (For some object formats, such as SOM for the HPPA, someexpressions are symbol-relative instead.)In this manual we use the notation {SECNAME N} to mean "offset Ninto section SECNAME."Apart from text, data and bss sections you need to know about the"absolute" section. When `ld' mixes partial programs, addresses in theabsolute section remain unchanged. For example, address `{absolute 0}'is "relocated" to run-time address 0 by `ld'. Although the linkernever arranges two partial programs' data sections with overlappingaddresses after linking, _by definition_ their absolute sections mustoverlap. Address `{absolute 239}' in one part of a program is alwaysthe same address when the program is running as address `{absolute239}' in any other part of the program.The idea of sections is extended to the "undefined" section. Anyaddress whose section is unknown at assembly time is by definitionrendered {undefined U}--where U is filled in later. Since numbers arealways defined, the only way to generate an undefined address is tomention an undefined symbol. A reference to a named common block wouldbe such a symbol: its value is unknown at assembly time so it hassection _undefined_.By analogy the word _section_ is used to describe groups of sectionsin the linked program. `ld' puts all partial programs' text sectionsin contiguous addresses in the linked program. It is customary torefer to the _text section_ of a program, meaning all the addresses ofall partial programs' text sections. Likewise for data and bsssections.Some sections are manipulated by `ld'; others are invented for useof `as' and have no meaning except during assembly.File: as.info, Node: Ld Sections, Next: As Sections, Prev: Secs Background, Up: Sections4.2 Linker Sections===================`ld' deals with just four kinds of sections, summarized below.*named sections**text section**data section*These sections hold your program. `as' and `ld' treat them asseparate but equal sections. Anything you can say of one sectionis true of another. When the program is running, however, it iscustomary for the text section to be unalterable. The textsection is often shared among processes: it contains instructions,constants and the like. The data section of a running program isusually alterable: for example, C variables would be stored in thedata section.*bss section*This section contains zeroed bytes when your program beginsrunning. It is used to hold uninitialized variables or commonstorage. The length of each partial program's bss section isimportant, but because it starts out containing zeroed bytes thereis no need to store explicit zero bytes in the object file. Thebss section was invented to eliminate those explicit zeros fromobject files.*absolute section*Address 0 of this section is always "relocated" to runtime address0. This is useful if you want to refer to an address that `ld'must not change when relocating. In this sense we speak ofabsolute addresses being "unrelocatable": they do not changeduring relocation.*undefined section*This "section" is a catch-all for address references to objectsnot in the preceding sections.An idealized example of three relocatable sections follows. Theexample uses the traditional section names `.text' and `.data'. Memoryaddresses are on the horizontal axis.+-----+----+--+partial program # 1: |ttttt|dddd|00|+-----+----+--+text data bssseg. seg. seg.+---+---+---+partial program # 2: |TTT|DDD|000|+---+---+---++--+---+-----+--+----+---+-----+~~linked program: | |TTT|ttttt| |dddd|DDD|00000|+--+---+-----+--+----+---+-----+~~addresses: 0 ...File: as.info, Node: As Sections, Next: Sub-Sections, Prev: Ld Sections, Up: Sections4.3 Assembler Internal Sections===============================These sections are meant only for the internal use of `as'. They haveno meaning at run-time. You do not really need to know about thesesections for most purposes; but they can be mentioned in `as' warningmessages, so it might be helpful to have an idea of their meanings to`as'. These sections are used to permit the value of every expressionin your assembly language program to be a section-relative address.ASSEMBLER-INTERNAL-LOGIC-ERROR!An internal assembler logic error has been found. This meansthere is a bug in the assembler.expr sectionThe assembler stores complex expression internally as combinationsof symbols. When it needs to represent an expression as a symbol,it puts it in the expr section.File: as.info, Node: Sub-Sections, Next: bss, Prev: As Sections, Up: Sections4.4 Sub-Sections================Assembled bytes conventionally fall into two sections: text and data.You may have separate groups of data in named sections that you want toend up near to each other in the object file, even though they are notcontiguous in the assembler source. `as' allows you to use"subsections" for this purpose. Within each section, there can benumbered subsections with values from 0 to 8192. Objects assembledinto the same subsection go into the object file together with otherobjects in the same subsection. For example, a compiler might want tostore constants in the text section, but might not want to have theminterspersed with the program being assembled. In this case, thecompiler could issue a `.text 0' before each section of code beingoutput, and a `.text 1' before each group of constants being output.Subsections are optional. If you do not use subsections, everythinggoes in subsection number zero.Each subsection is zero-padded up to a multiple of four bytes.(Subsections may be padded a different amount on different flavors of`as'.)Subsections appear in your object file in numeric order, lowestnumbered to highest. (All this to be compatible with other people'sassemblers.) The object file contains no representation ofsubsections; `ld' and other programs that manipulate object files seeno trace of them. They just see all your text subsections as a textsection, and all your data subsections as a data section.To specify which subsection you want subsequent statements assembledinto, use a numeric argument to specify it, in a `.text EXPRESSION' ora `.data EXPRESSION' statement. When generating COFF output, you canalso use an extra subsection argument with arbitrary named sections:`.section NAME, EXPRESSION'. When generating ELF output, you can alsouse the `.subsection' directive (*note SubSection::) to specify asubsection: `.subsection EXPRESSION'. EXPRESSION should be an absoluteexpression (*note Expressions::). If you just say `.text' then `.text0' is assumed. Likewise `.data' means `.data 0'. Assembly begins in`text 0'. For instance:.text 0 # The default subsection is text 0 anyway..ascii "This lives in the first text subsection. *".text 1.ascii "But this lives in the second text subsection.".data 0.ascii "This lives in the data section,".ascii "in the first data subsection.".text 0.ascii "This lives in the first text section,".ascii "immediately following the asterisk (*)."Each section has a "location counter" incremented by one for everybyte assembled into that section. Because subsections are merely aconvenience restricted to `as' there is no concept of a subsectionlocation counter. There is no way to directly manipulate a locationcounter--but the `.align' directive changes it, and any labeldefinition captures its current value. The location counter of thesection where statements are being assembled is said to be the "active"location counter.File: as.info, Node: bss, Prev: Sub-Sections, Up: Sections4.5 bss Section===============The bss section is used for local common variable storage. You mayallocate address space in the bss section, but you may not dictate datato load into it before your program executes. When your program startsrunning, all the contents of the bss section are zeroed bytes.The `.lcomm' pseudo-op defines a symbol in the bss section; see*Note `.lcomm': Lcomm.The `.comm' pseudo-op may be used to declare a common symbol, whichis another form of uninitialized symbol; see *Note `.comm': Comm.When assembling for a target which supports multiple sections, suchas ELF or COFF, you may switch into the `.bss' section and definesymbols as usual; see *Note `.section': Section. You may only assemblezero values into the section. Typically the section will only containsymbol definitions and `.skip' directives (*note `.skip': Skip.).File: as.info, Node: Symbols, Next: Expressions, Prev: Sections, Up: Top5 Symbols*********Symbols are a central concept: the programmer uses symbols to namethings, the linker uses symbols to link, and the debugger uses symbolsto debug._Warning:_ `as' does not place symbols in the object file in thesame order they were declared. This may break some debuggers.* Menu:* Labels:: Labels* Setting Symbols:: Giving Symbols Other Values* Symbol Names:: Symbol Names* Dot:: The Special Dot Symbol* Symbol Attributes:: Symbol AttributesFile: as.info, Node: Labels, Next: Setting Symbols, Up: Symbols5.1 Labels==========A "label" is written as a symbol immediately followed by a colon `:'.The symbol then represents the current value of the active locationcounter, and is, for example, a suitable instruction operand. You arewarned if you use the same symbol to represent two different locations:the first definition overrides any other definitions.On the HPPA, the usual form for a label need not be immediatelyfollowed by a colon, but instead must start in column zero. Only onelabel may be defined on a single line. To work around this, the HPPAversion of `as' also provides a special directive `.label' for defininglabels more flexibly.File: as.info, Node: Setting Symbols, Next: Symbol Names, Prev: Labels, Up: Symbols5.2 Giving Symbols Other Values===============================A symbol can be given an arbitrary value by writing a symbol, followedby an equals sign `=', followed by an expression (*note Expressions::).This is equivalent to using the `.set' directive. *Note `.set': Set.In the same way, using a double equals sign `='`=' here represents anequivalent of the `.eqv' directive. *Note `.eqv': Eqv.File: as.info, Node: Symbol Names, Next: Dot, Prev: Setting Symbols, Up: Symbols5.3 Symbol Names================Symbol names begin with a letter or with one of `._'. On mostmachines, you can also use `$' in symbol names; exceptions are noted in*Note Machine Dependencies::. That character may be followed by anystring of digits, letters, dollar signs (unless otherwise noted for aparticular target machine), and underscores.Case of letters is significant: `foo' is a different symbol name than`Foo'.Each symbol has exactly one name. Each name in an assembly languageprogram refers to exactly one symbol. You may use that symbol name anynumber of times in a program.Local Symbol Names------------------A local symbol is any symbol beginning with certain local labelprefixes. By default, the local label prefix is `.L' for ELF systems or`L' for traditional a.out systems, but each target may have its own setof local label prefixes. On the HPPA local symbols begin with `L$'.Local symbols are defined and used within the assembler, but they arenormally not saved in object files. Thus, they are not visible whendebugging. You may use the `-L' option (*note Include Local Symbols:`-L': L.) to retain the local symbols in the object files.Local Labels------------Local labels help compilers and programmers use names temporarily.They create symbols which are guaranteed to be unique over the entirescope of the input source code and which can be referred to by a simplenotation. To define a local label, write a label of the form `N:'(where N represents any positive integer). To refer to the most recentprevious definition of that label write `Nb', using the same number aswhen you defined the label. To refer to the next definition of a locallabel, write `Nf'--the `b' stands for "backwards" and the `f' standsfor "forwards".There is no restriction on how you can use these labels, and you canreuse them too. So that it is possible to repeatedly define the samelocal label (using the same number `N'), although you can only refer tothe most recently defined local label of that number (for a backwardsreference) or the next definition of a specific local label for aforward reference. It is also worth noting that the first 10 locallabels (`0:'...`9:') are implemented in a slightly more efficientmanner than the others.Here is an example:1: branch 1f2: branch 1b1: branch 2f2: branch 1bWhich is the equivalent of:label_1: branch label_3label_2: branch label_1label_3: branch label_4label_4: branch label_3Local label names are only a notational device. They are immediatelytransformed into more conventional symbol names before the assembleruses them. The symbol names are stored in the symbol table, appear inerror messages, and are optionally emitted to the object file. Thenames are constructed using these parts:`_local label prefix_'All local symbols begin with the system-specific local labelprefix. Normally both `as' and `ld' forget symbols that startwith the local label prefix. These labels are used for symbolsyou are never intended to see. If you use the `-L' option then`as' retains these symbols in the object file. If you alsoinstruct `ld' to retain these symbols, you may use them indebugging.`NUMBER'This is the number that was used in the local label definition.So if the label is written `55:' then the number is `55'.`C-B'This unusual character is included so you do not accidentallyinvent a symbol of the same name. The character has ASCII valueof `\002' (control-B).`_ordinal number_'This is a serial number to keep the labels distinct. The firstdefinition of `0:' gets the number `1'. The 15th definition of`0:' gets the number `15', and so on. Likewise the firstdefinition of `1:' gets the number `1' and its 15th definitiongets `15' as well.So for example, the first `1:' may be named `.L1C-B1', and the 44th`3:' may be named `.L3C-B44'.Dollar Local Labels-------------------`as' also supports an even more local form of local labels calleddollar labels. These labels go out of scope (i.e., they becomeundefined) as soon as a non-local label is defined. Thus they remainvalid for only a small region of the input source code. Normal locallabels, by contrast, remain in scope for the entire file, or until theyare redefined by another occurrence of the same local label.Dollar labels are defined in exactly the same way as ordinary locallabels, except that instead of being terminated by a colon, they areterminated by a dollar sign, e.g., `55$'.They can also be distinguished from ordinary local labels by theirtransformed names which use ASCII character `\001' (control-A) as themagic character to distinguish them from ordinary labels. For example,the fifth definition of `6$' may be named `.L6C-A5'.File: as.info, Node: Dot, Next: Symbol Attributes, Prev: Symbol Names, Up: Symbols5.4 The Special Dot Symbol==========================The special symbol `.' refers to the current address that `as' isassembling into. Thus, the expression `melvin: .long .' defines`melvin' to contain its own address. Assigning a value to `.' istreated the same as a `.org' directive. Thus, the expression `.=.+4'is the same as saying `.space 4'.File: as.info, Node: Symbol Attributes, Prev: Dot, Up: Symbols5.5 Symbol Attributes=====================Every symbol has, as well as its name, the attributes "Value" and"Type". Depending on output format, symbols can also have auxiliaryattributes.If you use a symbol without defining it, `as' assumes zero for allthese attributes, and probably won't warn you. This makes the symbolan externally defined symbol, which is generally what you would want.* Menu:* Symbol Value:: Value* Symbol Type:: Type* a.out Symbols:: Symbol Attributes: `a.out'* COFF Symbols:: Symbol Attributes for COFF* SOM Symbols:: Symbol Attributes for SOMFile: as.info, Node: Symbol Value, Next: Symbol Type, Up: Symbol Attributes5.5.1 Value-----------The value of a symbol is (usually) 32 bits. For a symbol which labels alocation in the text, data, bss or absolute sections the value is thenumber of addresses from the start of that section to the label.Naturally for text, data and bss sections the value of a symbol changesas `ld' changes section base addresses during linking. Absolutesymbols' values do not change during linking: that is why they arecalled absolute.The value of an undefined symbol is treated in a special way. If itis 0 then the symbol is not defined in this assembler source file, and`ld' tries to determine its value from other files linked into the sameprogram. You make this kind of symbol simply by mentioning a symbolname without defining it. A non-zero value represents a `.comm' commondeclaration. The value is how much common storage to reserve, in bytes(addresses). The symbol refers to the first address of the allocatedstorage.File: as.info, Node: Symbol Type, Next: a.out Symbols, Prev: Symbol Value, Up: Symbol Attributes5.5.2 Type----------The type attribute of a symbol contains relocation (section)information, any flag settings indicating that a symbol is external, and(optionally), other information for linkers and debuggers. The exactformat depends on the object-code output format in use.File: as.info, Node: a.out Symbols, Next: COFF Symbols, Prev: Symbol Type, Up: Symbol Attributes5.5.3 Symbol Attributes: `a.out'--------------------------------* Menu:* Symbol Desc:: Descriptor* Symbol Other:: OtherFile: as.info, Node: Symbol Desc, Next: Symbol Other, Up: a.out Symbols5.5.3.1 Descriptor..................This is an arbitrary 16-bit value. You may establish a symbol'sdescriptor value by using a `.desc' statement (*note `.desc': Desc.).A descriptor value means nothing to `as'.File: as.info, Node: Symbol Other, Prev: Symbol Desc, Up: a.out Symbols5.5.3.2 Other.............This is an arbitrary 8-bit value. It means nothing to `as'.File: as.info, Node: COFF Symbols, Next: SOM Symbols, Prev: a.out Symbols, Up: Symbol Attributes5.5.4 Symbol Attributes for COFF--------------------------------The COFF format supports a multitude of auxiliary symbol attributes;like the primary symbol attributes, they are set between `.def' and`.endef' directives.5.5.4.1 Primary Attributes..........................The symbol name is set with `.def'; the value and type, respectively,with `.val' and `.type'.5.5.4.2 Auxiliary Attributes............................The `as' directives `.dim', `.line', `.scl', `.size', `.tag', and`.weak' can generate auxiliary symbol table information for COFF.File: as.info, Node: SOM Symbols, Prev: COFF Symbols, Up: Symbol Attributes5.5.5 Symbol Attributes for SOM-------------------------------The SOM format for the HPPA supports a multitude of symbol attributesset with the `.EXPORT' and `.IMPORT' directives.The attributes are described in `HP9000 Series 800 Assembly LanguageReference Manual' (HP 92432-90001) under the `IMPORT' and `EXPORT'assembler directive documentation.File: as.info, Node: Expressions, Next: Pseudo Ops, Prev: Symbols, Up: Top6 Expressions*************An "expression" specifies an address or numeric value. Whitespace mayprecede and/or follow an expression.The result of an expression must be an absolute number, or else anoffset into a particular section. If an expression is not absolute,and there is not enough information when `as' sees the expression toknow its section, a second pass over the source program might benecessary to interpret the expression--but the second pass is currentlynot implemented. `as' aborts with an error message in this situation.* Menu:* Empty Exprs:: Empty Expressions* Integer Exprs:: Integer ExpressionsFile: as.info, Node: Empty Exprs, Next: Integer Exprs, Up: Expressions6.1 Empty Expressions=====================An empty expression has no value: it is just whitespace or null.Wherever an absolute expression is required, you may omit theexpression, and `as' assumes a value of (absolute) 0. This iscompatible with other assemblers.File: as.info, Node: Integer Exprs, Prev: Empty Exprs, Up: Expressions6.2 Integer Expressions=======================An "integer expression" is one or more _arguments_ delimited by_operators_.* Menu:* Arguments:: Arguments* Operators:: Operators* Prefix Ops:: Prefix Operators* Infix Ops:: Infix OperatorsFile: as.info, Node: Arguments, Next: Operators, Up: Integer Exprs6.2.1 Arguments---------------"Arguments" are symbols, numbers or subexpressions. In other contextsarguments are sometimes called "arithmetic operands". In this manual,to avoid confusing them with the "instruction operands" of the machinelanguage, we use the term "argument" to refer to parts of expressionsonly, reserving the word "operand" to refer only to machine instructionoperands.Symbols are evaluated to yield {SECTION NNN} where SECTION is one oftext, data, bss, absolute, or undefined. NNN is a signed, 2'scomplement 32 bit integer.Numbers are usually integers.A number can be a flonum or bignum. In this case, you are warnedthat only the low order 32 bits are used, and `as' pretends these 32bits are an integer. You may write integer-manipulating instructionsthat act on exotic constants, compatible with other assemblers.Subexpressions are a left parenthesis `(' followed by an integerexpression, followed by a right parenthesis `)'; or a prefix operatorfollowed by an argument.File: as.info, Node: Operators, Next: Prefix Ops, Prev: Arguments, Up: Integer Exprs6.2.2 Operators---------------"Operators" are arithmetic functions, like `+' or `%'. Prefixoperators are followed by an argument. Infix operators appear betweentheir arguments. Operators may be preceded and/or followed bywhitespace.File: as.info, Node: Prefix Ops, Next: Infix Ops, Prev: Operators, Up: Integer Exprs6.2.3 Prefix Operator---------------------`as' has the following "prefix operators". They each take oneargument, which must be absolute.`-'"Negation". Two's complement negation.`~'"Complementation". Bitwise not.File: as.info, Node: Infix Ops, Prev: Prefix Ops, Up: Integer Exprs6.2.4 Infix Operators---------------------"Infix operators" take two arguments, one on either side. Operatorshave precedence, but operations with equal precedence are performed leftto right. Apart from `+' or `-', both arguments must be absolute, andthe result is absolute.1. Highest Precedence`*'"Multiplication".`/'"Division". Truncation is the same as the C operator `/'`%'"Remainder".`<<'"Shift Left". Same as the C operator `<<'.`>>'"Shift Right". Same as the C operator `>>'.2. Intermediate precedence`|'"Bitwise Inclusive Or".`&'"Bitwise And".`^'"Bitwise Exclusive Or".`!'"Bitwise Or Not".3. Low Precedence`+'"Addition". If either argument is absolute, the result hasthe section of the other argument. You may not add togetherarguments from different sections.`-'"Subtraction". If the right argument is absolute, the resulthas the section of the left argument. If both arguments arein the same section, the result is absolute. You may notsubtract arguments from different sections.`=='"Is Equal To"`<>'`!='"Is Not Equal To"`<'"Is Less Than"`>'"Is Greater Than"`>='"Is Greater Than Or Equal To"`<='"Is Less Than Or Equal To"The comparison operators can be used as infix operators. Atrue results has a value of -1 whereas a false result has avalue of 0. Note, these operators perform signedcomparisons.4. Lowest Precedence`&&'"Logical And".`||'"Logical Or".These two logical operations can be used to combine theresults of sub expressions. Note, unlike the comparisonoperators a true result returns a value of 1 but a falseresults does still return 0. Also note that the logical oroperator has a slightly lower precedence than logical and.In short, it's only meaningful to add or subtract the _offsets_ in anaddress; you can only have a defined section in one of the twoarguments.File: as.info, Node: Pseudo Ops, Next: Object Attributes, Prev: Expressions, Up: Top7 Assembler Directives**********************All assembler directives have names that begin with a period (`.').The rest of the name is letters, usually in lower case.This chapter discusses directives that are available regardless ofthe target machine configuration for the GNU assembler. Some machineconfigurations provide additional directives. *Note MachineDependencies::.* Menu:* Abort:: `.abort'* ABORT (COFF):: `.ABORT'* Align:: `.align ABS-EXPR , ABS-EXPR'* Altmacro:: `.altmacro'* Ascii:: `.ascii "STRING"'...* Asciz:: `.asciz "STRING"'...* Balign:: `.balign ABS-EXPR , ABS-EXPR'* Byte:: `.byte EXPRESSIONS'* Comm:: `.comm SYMBOL , LENGTH '* CFI directives:: `.cfi_startproc [simple]', `.cfi_endproc', etc.* Data:: `.data SUBSECTION'* Def:: `.def NAME'* Desc:: `.desc SYMBOL, ABS-EXPRESSION'* Dim:: `.dim'* Double:: `.double FLONUMS'* Eject:: `.eject'* Else:: `.else'* Elseif:: `.elseif'* End:: `.end'* Endef:: `.endef'* Endfunc:: `.endfunc'* Endif:: `.endif'* Equ:: `.equ SYMBOL, EXPRESSION'* Equiv:: `.equiv SYMBOL, EXPRESSION'* Eqv:: `.eqv SYMBOL, EXPRESSION'* Err:: `.err'* Error:: `.error STRING'* Exitm:: `.exitm'* Extern:: `.extern'* Fail:: `.fail'* File:: `.file STRING'* Fill:: `.fill REPEAT , SIZE , VALUE'* Float:: `.float FLONUMS'* Func:: `.func'* Global:: `.global SYMBOL', `.globl SYMBOL'* Gnu_attribute:: `.gnu_attribute TAG,VALUE'* Hidden:: `.hidden NAMES'* hword:: `.hword EXPRESSIONS'* Ident:: `.ident'* If:: `.if ABSOLUTE EXPRESSION'* Incbin:: `.incbin "FILE"[,SKIP[,COUNT]]'* Include:: `.include "FILE"'* Int:: `.int EXPRESSIONS'* Internal:: `.internal NAMES'* Irp:: `.irp SYMBOL,VALUES'...* Irpc:: `.irpc SYMBOL,VALUES'...* Lcomm:: `.lcomm SYMBOL , LENGTH'* Lflags:: `.lflags'* Line:: `.line LINE-NUMBER'* Linkonce:: `.linkonce [TYPE]'* List:: `.list'* Ln:: `.ln LINE-NUMBER'* LNS directives:: `.file', `.loc', etc.* Long:: `.long EXPRESSIONS'* Macro:: `.macro NAME ARGS'...* MRI:: `.mri VAL'* Noaltmacro:: `.noaltmacro'* Nolist:: `.nolist'* Octa:: `.octa BIGNUMS'* Org:: `.org NEW-LC, FILL'* P2align:: `.p2align ABS-EXPR, ABS-EXPR, ABS-EXPR'* PopSection:: `.popsection'* Previous:: `.previous'* Print:: `.print STRING'* Protected:: `.protected NAMES'* Psize:: `.psize LINES, COLUMNS'* Purgem:: `.purgem NAME'* PushSection:: `.pushsection NAME'* Quad:: `.quad BIGNUMS'* Reloc:: `.reloc OFFSET, RELOC_NAME[, EXPRESSION]'* Rept:: `.rept COUNT'* Sbttl:: `.sbttl "SUBHEADING"'* Scl:: `.scl CLASS'* Section:: `.section NAME[, FLAGS]'* Set:: `.set SYMBOL, EXPRESSION'* Short:: `.short EXPRESSIONS'* Single:: `.single FLONUMS'* Size:: `.size [NAME , EXPRESSION]'* Skip:: `.skip SIZE , FILL'* Sleb128:: `.sleb128 EXPRESSIONS'* Space:: `.space SIZE , FILL'* Stab:: `.stabd, .stabn, .stabs'* String:: `.string "STR"', `.string8 "STR"', `.string16 "STR"', `.string32 "STR"', `.string64 "STR"'* Struct:: `.struct EXPRESSION'* SubSection:: `.subsection'* Symver:: `.symver NAME,NAME2@NODENAME'* Tag:: `.tag STRUCTNAME'* Text:: `.text SUBSECTION'* Title:: `.title "HEADING"'* Type:: `.type <INT | NAME , TYPE DESCRIPTION>'* Uleb128:: `.uleb128 EXPRESSIONS'* Val:: `.val ADDR'* Version:: `.version "STRING"'* VTableEntry:: `.vtable_entry TABLE, OFFSET'* VTableInherit:: `.vtable_inherit CHILD, PARENT'* Warning:: `.warning STRING'* Weak:: `.weak NAMES'* Weakref:: `.weakref ALIAS, SYMBOL'* Word:: `.word EXPRESSIONS'* Deprecated:: Deprecated DirectivesFile: as.info, Node: Abort, Next: ABORT (COFF), Up: Pseudo Ops7.1 `.abort'============This directive stops the assembly immediately. It is for compatibilitywith other assemblers. The original idea was that the assemblylanguage source would be piped into the assembler. If the sender ofthe source quit, it could use this directive tells `as' to quit also.One day `.abort' will not be supported.File: as.info, Node: ABORT (COFF), Next: Align, Prev: Abort, Up: Pseudo Ops7.2 `.ABORT' (COFF)===================When producing COFF output, `as' accepts this directive as a synonymfor `.abort'.File: as.info, Node: Align, Next: Altmacro, Prev: ABORT (COFF), Up: Pseudo Ops7.3 `.align ABS-EXPR, ABS-EXPR, ABS-EXPR'=========================================Pad the location counter (in the current subsection) to a particularstorage boundary. The first expression (which must be absolute) is thealignment required, as described below.The second expression (also absolute) gives the fill value to bestored in the padding bytes. It (and the comma) may be omitted. If itis omitted, the padding bytes are normally zero. However, on somesystems, if the section is marked as containing code and the fill valueis omitted, the space is filled with no-op instructions.The third expression is also absolute, and is also optional. If itis present, it is the maximum number of bytes that should be skipped bythis alignment directive. If doing the alignment would requireskipping more bytes than the specified maximum, then the alignment isnot done at all. You can omit the fill value (the second argument)entirely by simply using two commas after the required alignment; thiscan be useful if you want the alignment to be filled with no-opinstructions when appropriate.The way the required alignment is specified varies from system tosystem. For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32,s390, sparc, tic4x, tic80 and xtensa, the first expression is thealignment request in bytes. For example `.align 8' advances thelocation counter until it is a multiple of 8. If the location counteris already a multiple of 8, no change is needed. For the tic54x, thefirst expression is the alignment request in words.For other systems, including ppc, i386 using a.out format, arm andstrongarm, it is the number of low-order zero bits the location countermust have after advancement. For example `.align 3' advances thelocation counter until it a multiple of 8. If the location counter isalready a multiple of 8, no change is needed.This inconsistency is due to the different behaviors of the variousnative assemblers for these systems which GAS must emulate. GAS alsoprovides `.balign' and `.p2align' directives, described later, whichhave a consistent behavior across all architectures (but are specificto GAS).File: as.info, Node: Ascii, Next: Asciz, Prev: Altmacro, Up: Pseudo Ops7.4 `.ascii "STRING"'...========================`.ascii' expects zero or more string literals (*note Strings::)separated by commas. It assembles each string (with no automatictrailing zero byte) into consecutive addresses.File: as.info, Node: Asciz, Next: Balign, Prev: Ascii, Up: Pseudo Ops7.5 `.asciz "STRING"'...========================`.asciz' is just like `.ascii', but each string is followed by a zerobyte. The "z" in `.asciz' stands for "zero".File: as.info, Node: Balign, Next: Byte, Prev: Asciz, Up: Pseudo Ops7.6 `.balign[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'==============================================Pad the location counter (in the current subsection) to a particularstorage boundary. The first expression (which must be absolute) is thealignment request in bytes. For example `.balign 8' advances thelocation counter until it is a multiple of 8. If the location counteris already a multiple of 8, no change is needed.The second expression (also absolute) gives the fill value to bestored in the padding bytes. It (and the comma) may be omitted. If itis omitted, the padding bytes are normally zero. However, on somesystems, if the section is marked as containing code and the fill valueis omitted, the space is filled with no-op instructions.The third expression is also absolute, and is also optional. If itis present, it is the maximum number of bytes that should be skipped bythis alignment directive. If doing the alignment would requireskipping more bytes than the specified maximum, then the alignment isnot done at all. You can omit the fill value (the second argument)entirely by simply using two commas after the required alignment; thiscan be useful if you want the alignment to be filled with no-opinstructions when appropriate.The `.balignw' and `.balignl' directives are variants of the`.balign' directive. The `.balignw' directive treats the fill patternas a two byte word value. The `.balignl' directives treats the fillpattern as a four byte longword value. For example, `.balignw4,0x368d' will align to a multiple of 4. If it skips two bytes, theywill be filled in with the value 0x368d (the exact placement of thebytes depends upon the endianness of the processor). If it skips 1 or3 bytes, the fill value is undefined.File: as.info, Node: Byte, Next: Comm, Prev: Balign, Up: Pseudo Ops7.7 `.byte EXPRESSIONS'=======================`.byte' expects zero or more expressions, separated by commas. Eachexpression is assembled into the next byte.File: as.info, Node: Comm, Next: CFI directives, Prev: Byte, Up: Pseudo Ops7.8 `.comm SYMBOL , LENGTH '============================`.comm' declares a common symbol named SYMBOL. When linking, a commonsymbol in one object file may be merged with a defined or common symbolof the same name in another object file. If `ld' does not see adefinition for the symbol-just one or more common symbols-then it willallocate LENGTH bytes of uninitialized memory. LENGTH must be anabsolute expression. If `ld' sees multiple common symbols with thesame name, and they do not all have the same size, it will allocatespace using the largest size.When using ELF, the `.comm' directive takes an optional thirdargument. This is the desired alignment of the symbol, specified as abyte boundary (for example, an alignment of 16 means that the leastsignificant 4 bits of the address should be zero). The alignment mustbe an absolute expression, and it must be a power of two. If `ld'allocates uninitialized memory for the common symbol, it will use thealignment when placing the symbol. If no alignment is specified, `as'will set the alignment to the largest power of two less than or equalto the size of the symbol, up to a maximum of 16.The syntax for `.comm' differs slightly on the HPPA. The syntax is`SYMBOL .comm, LENGTH'; SYMBOL is optional.File: as.info, Node: CFI directives, Next: Data, Prev: Comm, Up: Pseudo Ops7.9 `.cfi_startproc [simple]'=============================`.cfi_startproc' is used at the beginning of each function that shouldhave an entry in `.eh_frame'. It initializes some internal datastructures. Don't forget to close the function by `.cfi_endproc'.Unless `.cfi_startproc' is used along with parameter `simple' italso emits some architecture dependent initial CFI instructions.7.10 `.cfi_endproc'===================`.cfi_endproc' is used at the end of a function where it closes itsunwind entry previously opened by `.cfi_startproc', and emits it to`.eh_frame'.7.11 `.cfi_personality ENCODING [, EXP]'========================================`.cfi_personality' defines personality routine and its encoding.ENCODING must be a constant determining how the personality should beencoded. If it is 255 (`DW_EH_PE_omit'), second argument is notpresent, otherwise second argument should be a constant or a symbolname. When using indirect encodings, the symbol provided should be thelocation where personality can be loaded from, not the personalityroutine itself. The default after `.cfi_startproc' is`.cfi_personality 0xff', no personality routine.7.12 `.cfi_lsda ENCODING [, EXP]'=================================`.cfi_lsda' defines LSDA and its encoding. ENCODING must be a constantdetermining how the LSDA should be encoded. If it is 255(`DW_EH_PE_omit'), second argument is not present, otherwise secondargument should be a constant or a symbol name. The default after`.cfi_startproc' is `.cfi_lsda 0xff', no LSDA.7.13 `.cfi_def_cfa REGISTER, OFFSET'====================================`.cfi_def_cfa' defines a rule for computing CFA as: take address fromREGISTER and add OFFSET to it.7.14 `.cfi_def_cfa_register REGISTER'=====================================`.cfi_def_cfa_register' modifies a rule for computing CFA. From now onREGISTER will be used instead of the old one. Offset remains the same.7.15 `.cfi_def_cfa_offset OFFSET'=================================`.cfi_def_cfa_offset' modifies a rule for computing CFA. Registerremains the same, but OFFSET is new. Note that it is the absoluteoffset that will be added to a defined register to compute CFA address.7.16 `.cfi_adjust_cfa_offset OFFSET'====================================Same as `.cfi_def_cfa_offset' but OFFSET is a relative value that isadded/substracted from the previous offset.7.17 `.cfi_offset REGISTER, OFFSET'===================================Previous value of REGISTER is saved at offset OFFSET from CFA.7.18 `.cfi_rel_offset REGISTER, OFFSET'=======================================Previous value of REGISTER is saved at offset OFFSET from the currentCFA register. This is transformed to `.cfi_offset' using the knowndisplacement of the CFA register from the CFA. This is often easier touse, because the number will match the code it's annotating.7.19 `.cfi_register REGISTER1, REGISTER2'=========================================Previous value of REGISTER1 is saved in register REGISTER2.7.20 `.cfi_restore REGISTER'============================`.cfi_restore' says that the rule for REGISTER is now the same as itwas at the beginning of the function, after all initial instructionadded by `.cfi_startproc' were executed.7.21 `.cfi_undefined REGISTER'==============================From now on the previous value of REGISTER can't be restored anymore.7.22 `.cfi_same_value REGISTER'===============================Current value of REGISTER is the same like in the previous frame, i.e.no restoration needed.7.23 `.cfi_remember_state',===========================First save all current rules for all registers by `.cfi_remember_state',then totally screw them up by subsequent `.cfi_*' directives and wheneverything is hopelessly bad, use `.cfi_restore_state' to restore theprevious saved state.7.24 `.cfi_return_column REGISTER'==================================Change return column REGISTER, i.e. the return address is eitherdirectly in REGISTER or can be accessed by rules for REGISTER.7.25 `.cfi_signal_frame'========================Mark current function as signal trampoline.7.26 `.cfi_window_save'=======================SPARC register window has been saved.7.27 `.cfi_escape' EXPRESSION[, ...]====================================Allows the user to add arbitrary bytes to the unwind info. One mightuse this to add OS-specific CFI opcodes, or generic CFI opcodes thatGAS does not yet support.7.28 `.cfi_val_encoded_addr REGISTER, ENCODING, LABEL'======================================================The current value of REGISTER is LABEL. The value of LABEL will beencoded in the output file according to ENCODING; see the descriptionof `.cfi_personality' for details on this encoding.The usefulness of equating a register to a fixed label is probablylimited to the return address register. Here, it can be useful to marka code segment that has only one return address which is reached by adirect branch and no copy of the return address exists in memory oranother register.File: as.info, Node: LNS directives, Next: Long, Prev: Ln, Up: Pseudo Ops7.29 `.file FILENO FILENAME'============================When emitting dwarf2 line number information `.file' assigns filenamesto the `.debug_line' file name table. The FILENO operand should be aunique positive integer to use as the index of the entry in the table.The FILENAME operand is a C string literal.The detail of filename indices is exposed to the user because thefilename table is shared with the `.debug_info' section of the dwarf2debugging information, and thus the user must know the exact indicesthat table entries will have.7.30 `.loc FILENO LINENO [COLUMN] [OPTIONS]'============================================The `.loc' directive will add row to the `.debug_line' line numbermatrix corresponding to the immediately following assembly instruction.The FILENO, LINENO, and optional COLUMN arguments will be applied tothe `.debug_line' state machine before the row is added.The OPTIONS are a sequence of the following tokens in any order:`basic_block'This option will set the `basic_block' register in the`.debug_line' state machine to `true'.`prologue_end'This option will set the `prologue_end' register in the`.debug_line' state machine to `true'.`epilogue_begin'This option will set the `epilogue_begin' register in the`.debug_line' state machine to `true'.`is_stmt VALUE'This option will set the `is_stmt' register in the `.debug_line'state machine to `value', which must be either 0 or 1.`isa VALUE'This directive will set the `isa' register in the `.debug_line'state machine to VALUE, which must be an unsigned integer.7.31 `.loc_mark_labels ENABLE'==============================The `.loc_mark_labels' directive makes the assembler emit an entry tothe `.debug_line' line number matrix with the `basic_block' register inthe state machine set whenever a code label is seen. The ENABLEargument should be either 1 or 0, to enable or disable this functionrespectively.File: as.info, Node: Data, Next: Def, Prev: CFI directives, Up: Pseudo Ops7.32 `.data SUBSECTION'=======================`.data' tells `as' to assemble the following statements onto the end ofthe data subsection numbered SUBSECTION (which is an absoluteexpression). If SUBSECTION is omitted, it defaults to zero.File: as.info, Node: Def, Next: Desc, Prev: Data, Up: Pseudo Ops7.33 `.def NAME'================Begin defining debugging information for a symbol NAME; the definitionextends until the `.endef' directive is encountered.File: as.info, Node: Desc, Next: Dim, Prev: Def, Up: Pseudo Ops7.34 `.desc SYMBOL, ABS-EXPRESSION'===================================This directive sets the descriptor of the symbol (*note SymbolAttributes::) to the low 16 bits of an absolute expression.The `.desc' directive is not available when `as' is configured forCOFF output; it is only for `a.out' or `b.out' object format. For thesake of compatibility, `as' accepts it, but produces no output, whenconfigured for COFF.File: as.info, Node: Dim, Next: Double, Prev: Desc, Up: Pseudo Ops7.35 `.dim'===========This directive is generated by compilers to include auxiliary debugginginformation in the symbol table. It is only permitted inside`.def'/`.endef' pairs.File: as.info, Node: Double, Next: Eject, Prev: Dim, Up: Pseudo Ops7.36 `.double FLONUMS'======================`.double' expects zero or more flonums, separated by commas. Itassembles floating point numbers. The exact kind of floating pointnumbers emitted depends on how `as' is configured. *Note MachineDependencies::.File: as.info, Node: Eject, Next: Else, Prev: Double, Up: Pseudo Ops7.37 `.eject'=============Force a page break at this point, when generating assembly listings.File: as.info, Node: Else, Next: Elseif, Prev: Eject, Up: Pseudo Ops7.38 `.else'============`.else' is part of the `as' support for conditional assembly; see *Note`.if': If. It marks the beginning of a section of code to be assembledif the condition for the preceding `.if' was false.File: as.info, Node: Elseif, Next: End, Prev: Else, Up: Pseudo Ops7.39 `.elseif'==============`.elseif' is part of the `as' support for conditional assembly; see*Note `.if': If. It is shorthand for beginning a new `.if' block thatwould otherwise fill the entire `.else' section.File: as.info, Node: End, Next: Endef, Prev: Elseif, Up: Pseudo Ops7.40 `.end'===========`.end' marks the end of the assembly file. `as' does not processanything in the file past the `.end' directive.File: as.info, Node: Endef, Next: Endfunc, Prev: End, Up: Pseudo Ops7.41 `.endef'=============This directive flags the end of a symbol definition begun with `.def'.File: as.info, Node: Endfunc, Next: Endif, Prev: Endef, Up: Pseudo Ops7.42 `.endfunc'===============`.endfunc' marks the end of a function specified with `.func'.File: as.info, Node: Endif, Next: Equ, Prev: Endfunc, Up: Pseudo Ops7.43 `.endif'=============`.endif' is part of the `as' support for conditional assembly; it marksthe end of a block of code that is only assembled conditionally. *Note`.if': If.File: as.info, Node: Equ, Next: Equiv, Prev: Endif, Up: Pseudo Ops7.44 `.equ SYMBOL, EXPRESSION'==============================This directive sets the value of SYMBOL to EXPRESSION. It issynonymous with `.set'; see *Note `.set': Set.The syntax for `equ' on the HPPA is `SYMBOL .equ EXPRESSION'.The syntax for `equ' on the Z80 is `SYMBOL equ EXPRESSION'. On theZ80 it is an eror if SYMBOL is already defined, but the symbol is notprotected from later redefinition. Compare *Note Equiv::.File: as.info, Node: Equiv, Next: Eqv, Prev: Equ, Up: Pseudo Ops7.45 `.equiv SYMBOL, EXPRESSION'================================The `.equiv' directive is like `.equ' and `.set', except that theassembler will signal an error if SYMBOL is already defined. Note asymbol which has been referenced but not actually defined is consideredto be undefined.Except for the contents of the error message, this is roughlyequivalent to.ifdef SYM.err.endif.equ SYM,VALplus it protects the symbol from later redefinition.File: as.info, Node: Eqv, Next: Err, Prev: Equiv, Up: Pseudo Ops7.46 `.eqv SYMBOL, EXPRESSION'==============================The `.eqv' directive is like `.equiv', but no attempt is made toevaluate the expression or any part of it immediately. Instead eachtime the resulting symbol is used in an expression, a snapshot of itscurrent value is taken.File: as.info, Node: Err, Next: Error, Prev: Eqv, Up: Pseudo Ops7.47 `.err'===========If `as' assembles a `.err' directive, it will print an error messageand, unless the `-Z' option was used, it will not generate an objectfile. This can be used to signal an error in conditionally compiledcode.File: as.info, Node: Error, Next: Exitm, Prev: Err, Up: Pseudo Ops7.48 `.error "STRING"'======================Similarly to `.err', this directive emits an error, but you can specifya string that will be emitted as the error message. If you don'tspecify the message, it defaults to `".error directive invoked insource file"'. *Note Error and Warning Messages: Errors..error "This code has not been assembled and tested."File: as.info, Node: Exitm, Next: Extern, Prev: Error, Up: Pseudo Ops7.49 `.exitm'=============Exit early from the current macro definition. *Note Macro::.File: as.info, Node: Extern, Next: Fail, Prev: Exitm, Up: Pseudo Ops7.50 `.extern'==============`.extern' is accepted in the source program--for compatibility withother assemblers--but it is ignored. `as' treats all undefined symbolsas external.File: as.info, Node: Fail, Next: File, Prev: Extern, Up: Pseudo Ops7.51 `.fail EXPRESSION'=======================Generates an error or a warning. If the value of the EXPRESSION is 500or more, `as' will print a warning message. If the value is less than500, `as' will print an error message. The message will include thevalue of EXPRESSION. This can occasionally be useful inside complexnested macros or conditional assembly.File: as.info, Node: File, Next: Fill, Prev: Fail, Up: Pseudo Ops7.52 `.file STRING'===================`.file' tells `as' that we are about to start a new logical file.STRING is the new file name. In general, the filename is recognizedwhether or not it is surrounded by quotes `"'; but if you wish tospecify an empty file name, you must give the quotes-`""'. Thisstatement may go away in future: it is only recognized to be compatiblewith old `as' programs.File: as.info, Node: Fill, Next: Float, Prev: File, Up: Pseudo Ops7.53 `.fill REPEAT , SIZE , VALUE'==================================REPEAT, SIZE and VALUE are absolute expressions. This emits REPEATcopies of SIZE bytes. REPEAT may be zero or more. SIZE may be zero ormore, but if it is more than 8, then it is deemed to have the value 8,compatible with other people's assemblers. The contents of each REPEATbytes is taken from an 8-byte number. The highest order 4 bytes arezero. The lowest order 4 bytes are VALUE rendered in the byte-order ofan integer on the computer `as' is assembling for. Each SIZE bytes ina repetition is taken from the lowest order SIZE bytes of this number.Again, this bizarre behavior is compatible with other people'sassemblers.SIZE and VALUE are optional. If the second comma and VALUE areabsent, VALUE is assumed zero. If the first comma and following tokensare absent, SIZE is assumed to be 1.File: as.info, Node: Float, Next: Func, Prev: Fill, Up: Pseudo Ops7.54 `.float FLONUMS'=====================This directive assembles zero or more flonums, separated by commas. Ithas the same effect as `.single'. The exact kind of floating pointnumbers emitted depends on how `as' is configured. *Note MachineDependencies::.File: as.info, Node: Func, Next: Global, Prev: Float, Up: Pseudo Ops7.55 `.func NAME[,LABEL]'=========================`.func' emits debugging information to denote function NAME, and isignored unless the file is assembled with debugging enabled. Only`--gstabs[+]' is currently supported. LABEL is the entry point of thefunction and if omitted NAME prepended with the `leading char' is used.`leading char' is usually `_' or nothing, depending on the target. Allfunctions are currently defined to have `void' return type. Thefunction must be terminated with `.endfunc'.File: as.info, Node: Global, Next: Gnu_attribute, Prev: Func, Up: Pseudo Ops7.56 `.global SYMBOL', `.globl SYMBOL'======================================`.global' makes the symbol visible to `ld'. If you define SYMBOL inyour partial program, its value is made available to other partialprograms that are linked with it. Otherwise, SYMBOL takes itsattributes from a symbol of the same name from another file linked intothe same program.Both spellings (`.globl' and `.global') are accepted, forcompatibility with other assemblers.On the HPPA, `.global' is not always enough to make it accessible toother partial programs. You may need the HPPA-only `.EXPORT' directiveas well. *Note HPPA Assembler Directives: HPPA Directives.File: as.info, Node: Gnu_attribute, Next: Hidden, Prev: Global, Up: Pseudo Ops7.57 `.gnu_attribute TAG,VALUE'===============================Record a GNU object attribute for this file. *Note Object Attributes::.File: as.info, Node: Hidden, Next: hword, Prev: Gnu_attribute, Up: Pseudo Ops7.58 `.hidden NAMES'====================This is one of the ELF visibility directives. The other two are`.internal' (*note `.internal': Internal.) and `.protected' (*note`.protected': Protected.).This directive overrides the named symbols default visibility (whichis set by their binding: local, global or weak). The directive setsthe visibility to `hidden' which means that the symbols are not visibleto other components. Such symbols are always considered to be`protected' as well.File: as.info, Node: hword, Next: Ident, Prev: Hidden, Up: Pseudo Ops7.59 `.hword EXPRESSIONS'=========================This expects zero or more EXPRESSIONS, and emits a 16 bit number foreach.This directive is a synonym for `.short'; depending on the targetarchitecture, it may also be a synonym for `.word'.File: as.info, Node: Ident, Next: If, Prev: hword, Up: Pseudo Ops7.60 `.ident'=============This directive is used by some assemblers to place tags in objectfiles. The behavior of this directive varies depending on the target.When using the a.out object file format, `as' simply accepts thedirective for source-file compatibility with existing assemblers, butdoes not emit anything for it. When using COFF, comments are emittedto the `.comment' or `.rdata' section, depending on the target. Whenusing ELF, comments are emitted to the `.comment' section.File: as.info, Node: If, Next: Incbin, Prev: Ident, Up: Pseudo Ops7.61 `.if ABSOLUTE EXPRESSION'==============================`.if' marks the beginning of a section of code which is only consideredpart of the source program being assembled if the argument (which mustbe an ABSOLUTE EXPRESSION) is non-zero. The end of the conditionalsection of code must be marked by `.endif' (*note `.endif': Endif.);optionally, you may include code for the alternative condition, flaggedby `.else' (*note `.else': Else.). If you have several conditions tocheck, `.elseif' may be used to avoid nesting blocks if/else withineach subsequent `.else' block.The following variants of `.if' are also supported:`.ifdef SYMBOL'Assembles the following section of code if the specified SYMBOLhas been defined. Note a symbol which has been referenced but notyet defined is considered to be undefined.`.ifb TEXT'Assembles the following section of code if the operand is blank(empty).`.ifc STRING1,STRING2'Assembles the following section of code if the two strings are thesame. The strings may be optionally quoted with single quotes.If they are not quoted, the first string stops at the first comma,and the second string stops at the end of the line. Strings whichcontain whitespace should be quoted. The string comparison iscase sensitive.`.ifeq ABSOLUTE EXPRESSION'Assembles the following section of code if the argument is zero.`.ifeqs STRING1,STRING2'Another form of `.ifc'. The strings must be quoted using doublequotes.`.ifge ABSOLUTE EXPRESSION'Assembles the following section of code if the argument is greaterthan or equal to zero.`.ifgt ABSOLUTE EXPRESSION'Assembles the following section of code if the argument is greaterthan zero.`.ifle ABSOLUTE EXPRESSION'Assembles the following section of code if the argument is lessthan or equal to zero.`.iflt ABSOLUTE EXPRESSION'Assembles the following section of code if the argument is lessthan zero.`.ifnb TEXT'Like `.ifb', but the sense of the test is reversed: this assemblesthe following section of code if the operand is non-blank(non-empty).`.ifnc STRING1,STRING2.'Like `.ifc', but the sense of the test is reversed: this assemblesthe following section of code if the two strings are not the same.`.ifndef SYMBOL'`.ifnotdef SYMBOL'Assembles the following section of code if the specified SYMBOLhas not been defined. Both spelling variants are equivalent.Note a symbol which has been referenced but not yet defined isconsidered to be undefined.`.ifne ABSOLUTE EXPRESSION'Assembles the following section of code if the argument is notequal to zero (in other words, this is equivalent to `.if').`.ifnes STRING1,STRING2'Like `.ifeqs', but the sense of the test is reversed: thisassembles the following section of code if the two strings are notthe same.File: as.info, Node: Incbin, Next: Include, Prev: If, Up: Pseudo Ops7.62 `.incbin "FILE"[,SKIP[,COUNT]]'====================================The `incbin' directive includes FILE verbatim at the current location.You can control the search paths used with the `-I' command-line option(*note Command-Line Options: Invoking.). Quotation marks are requiredaround FILE.The SKIP argument skips a number of bytes from the start of theFILE. The COUNT argument indicates the maximum number of bytes toread. Note that the data is not aligned in any way, so it is the user'sresponsibility to make sure that proper alignment is provided bothbefore and after the `incbin' directive.File: as.info, Node: Include, Next: Int, Prev: Incbin, Up: Pseudo Ops7.63 `.include "FILE"'======================This directive provides a way to include supporting files at specifiedpoints in your source program. The code from FILE is assembled as ifit followed the point of the `.include'; when the end of the includedfile is reached, assembly of the original file continues. You cancontrol the search paths used with the `-I' command-line option (*noteCommand-Line Options: Invoking.). Quotation marks are required aroundFILE.File: as.info, Node: Int, Next: Internal, Prev: Include, Up: Pseudo Ops7.64 `.int EXPRESSIONS'=======================Expect zero or more EXPRESSIONS, of any section, separated by commas.For each expression, emit a number that, at run time, is the value ofthat expression. The byte order and bit size of the number depends onwhat kind of target the assembly is for.File: as.info, Node: Internal, Next: Irp, Prev: Int, Up: Pseudo Ops7.65 `.internal NAMES'======================This is one of the ELF visibility directives. The other two are`.hidden' (*note `.hidden': Hidden.) and `.protected' (*note`.protected': Protected.).This directive overrides the named symbols default visibility (whichis set by their binding: local, global or weak). The directive setsthe visibility to `internal' which means that the symbols areconsidered to be `hidden' (i.e., not visible to other components), andthat some extra, processor specific processing must also be performedupon the symbols as well.File: as.info, Node: Irp, Next: Irpc, Prev: Internal, Up: Pseudo Ops7.66 `.irp SYMBOL,VALUES'...============================Evaluate a sequence of statements assigning different values to SYMBOL.The sequence of statements starts at the `.irp' directive, and isterminated by an `.endr' directive. For each VALUE, SYMBOL is set toVALUE, and the sequence of statements is assembled. If no VALUE islisted, the sequence of statements is assembled once, with SYMBOL setto the null string. To refer to SYMBOL within the sequence ofstatements, use \SYMBOL.For example, assembling.irp param,1,2,3move d\param,sp@-.endris equivalent to assemblingmove d1,sp@-move d2,sp@-move d3,sp@-For some caveats with the spelling of SYMBOL, see also *Note Macro::.File: as.info, Node: Irpc, Next: Lcomm, Prev: Irp, Up: Pseudo Ops7.67 `.irpc SYMBOL,VALUES'...=============================Evaluate a sequence of statements assigning different values to SYMBOL.The sequence of statements starts at the `.irpc' directive, and isterminated by an `.endr' directive. For each character in VALUE,SYMBOL is set to the character, and the sequence of statements isassembled. If no VALUE is listed, the sequence of statements isassembled once, with SYMBOL set to the null string. To refer to SYMBOLwithin the sequence of statements, use \SYMBOL.For example, assembling.irpc param,123move d\param,sp@-.endris equivalent to assemblingmove d1,sp@-move d2,sp@-move d3,sp@-For some caveats with the spelling of SYMBOL, see also the discussionat *Note Macro::.File: as.info, Node: Lcomm, Next: Lflags, Prev: Irpc, Up: Pseudo Ops7.68 `.lcomm SYMBOL , LENGTH'=============================Reserve LENGTH (an absolute expression) bytes for a local commondenoted by SYMBOL. The section and value of SYMBOL are those of thenew local common. The addresses are allocated in the bss section, sothat at run-time the bytes start off zeroed. SYMBOL is not declaredglobal (*note `.global': Global.), so is normally not visible to `ld'.Some targets permit a third argument to be used with `.lcomm'. Thisargument specifies the desired alignment of the symbol in the bsssection.The syntax for `.lcomm' differs slightly on the HPPA. The syntax is`SYMBOL .lcomm, LENGTH'; SYMBOL is optional.File: as.info, Node: Lflags, Next: Line, Prev: Lcomm, Up: Pseudo Ops7.69 `.lflags'==============`as' accepts this directive, for compatibility with other assemblers,but ignores it.File: as.info, Node: Line, Next: Linkonce, Prev: Lflags, Up: Pseudo Ops7.70 `.line LINE-NUMBER'========================Change the logical line number. LINE-NUMBER must be an absoluteexpression. The next line has that logical line number. Therefore anyother statements on the current line (after a statement separatorcharacter) are reported as on logical line number LINE-NUMBER - 1. Oneday `as' will no longer support this directive: it is recognized onlyfor compatibility with existing assembler programs.Even though this is a directive associated with the `a.out' or`b.out' object-code formats, `as' still recognizes it when producingCOFF output, and treats `.line' as though it were the COFF `.ln' _if_it is found outside a `.def'/`.endef' pair.Inside a `.def', `.line' is, instead, one of the directives used bycompilers to generate auxiliary symbol information for debugging.File: as.info, Node: Linkonce, Next: List, Prev: Line, Up: Pseudo Ops7.71 `.linkonce [TYPE]'=======================Mark the current section so that the linker only includes a single copyof it. This may be used to include the same section in severaldifferent object files, but ensure that the linker will only include itonce in the final output file. The `.linkonce' pseudo-op must be usedfor each instance of the section. Duplicate sections are detectedbased on the section name, so it should be unique.This directive is only supported by a few object file formats; as ofthis writing, the only object file format which supports it is thePortable Executable format used on Windows NT.The TYPE argument is optional. If specified, it must be one of thefollowing strings. For example:.linkonce same_sizeNot all types may be supported on all object file formats.`discard'Silently discard duplicate sections. This is the default.`one_only'Warn if there are duplicate sections, but still keep only one copy.`same_size'Warn if any of the duplicates have different sizes.`same_contents'Warn if any of the duplicates do not have exactly the samecontents.File: as.info, Node: Ln, Next: LNS directives, Prev: List, Up: Pseudo Ops7.72 `.ln LINE-NUMBER'======================`.ln' is a synonym for `.line'.File: as.info, Node: MRI, Next: Noaltmacro, Prev: Macro, Up: Pseudo Ops7.73 `.mri VAL'===============If VAL is non-zero, this tells `as' to enter MRI mode. If VAL is zero,this tells `as' to exit MRI mode. This change affects code assembleduntil the next `.mri' directive, or until the end of the file. *NoteMRI mode: M.File: as.info, Node: List, Next: Ln, Prev: Linkonce, Up: Pseudo Ops7.74 `.list'============Control (in conjunction with the `.nolist' directive) whether or notassembly listings are generated. These two directives maintain aninternal counter (which is zero initially). `.list' increments thecounter, and `.nolist' decrements it. Assembly listings are generatedwhenever the counter is greater than zero.By default, listings are disabled. When you enable them (with the`-a' command line option; *note Command-Line Options: Invoking.), theinitial value of the listing counter is one.File: as.info, Node: Long, Next: Macro, Prev: LNS directives, Up: Pseudo Ops7.75 `.long EXPRESSIONS'========================`.long' is the same as `.int'. *Note `.int': Int.File: as.info, Node: Macro, Next: MRI, Prev: Long, Up: Pseudo Ops7.76 `.macro'=============The commands `.macro' and `.endm' allow you to define macros thatgenerate assembly output. For example, this definition specifies amacro `sum' that puts a sequence of numbers into memory:.macro sum from=0, to=5.long \from.if \to-\fromsum "(\from+1)",\to.endif.endmWith that definition, `SUM 0,5' is equivalent to this assembly input:.long 0.long 1.long 2.long 3.long 4.long 5`.macro MACNAME'`.macro MACNAME MACARGS ...'Begin the definition of a macro called MACNAME. If your macrodefinition requires arguments, specify their names after the macroname, separated by commas or spaces. You can qualify the macroargument to indicate whether all invocations must specify anon-blank value (through `:`req''), or whether it takes all of theremaining arguments (through `:`vararg''). You can supply adefault value for any macro argument by following the name with`=DEFLT'. You cannot define two macros with the same MACNAMEunless it has been subject to the `.purgem' directive (*notePurgem::) between the two definitions. For example, these are allvalid `.macro' statements:`.macro comm'Begin the definition of a macro called `comm', which takes noarguments.`.macro plus1 p, p1'`.macro plus1 p p1'Either statement begins the definition of a macro called`plus1', which takes two arguments; within the macrodefinition, write `\p' or `\p1' to evaluate the arguments.`.macro reserve_str p1=0 p2'Begin the definition of a macro called `reserve_str', with twoarguments. The first argument has a default value, but notthe second. After the definition is complete, you can callthe macro either as `reserve_str A,B' (with `\p1' evaluatingto A and `\p2' evaluating to B), or as `reserve_str ,B' (with`\p1' evaluating as the default, in this case `0', and `\p2'evaluating to B).`.macro m p1:req, p2=0, p3:vararg'Begin the definition of a macro called `m', with at leastthree arguments. The first argument must always have a valuespecified, but not the second, which instead has a defaultvalue. The third formal will get assigned all remainingarguments specified at invocation time.When you call a macro, you can specify the argument valueseither by position, or by keyword. For example, `sum 9,17'is equivalent to `sum to=17, from=9'.Note that since each of the MACARGS can be an identifier exactlyas any other one permitted by the target architecture, there may beoccasional problems if the target hand-crafts special meanings tocertain characters when they occur in a special position. Forexample, if the colon (`:') is generally permitted to be part of asymbol name, but the architecture specific code special-cases itwhen occurring as the final character of a symbol (to denote alabel), then the macro parameter replacement code will have no wayof knowing that and consider the whole construct (including thecolon) an identifier, and check only this identifier for being thesubject to parameter substitution. So for example this macrodefinition:.macro label l\l:.endmmight not work as expected. Invoking `label foo' might not createa label called `foo' but instead just insert the text `\l:' intothe assembler source, probably generating an error about anunrecognised identifier.Similarly problems might occur with the period character (`.')which is often allowed inside opcode names (and hence identifiernames). So for example constructing a macro to build an opcodefrom a base name and a length specifier like this:.macro opcode base length\base.\length.endmand invoking it as `opcode store l' will not create a `store.l'instruction but instead generate some kind of error as theassembler tries to interpret the text `\base.\length'.There are several possible ways around this problem:`Insert white space'If it is possible to use white space characters then this isthe simplest solution. eg:.macro label l\l :.endm`Use `\()''The string `\()' can be used to separate the end of a macroargument from the following text. eg:.macro opcode base length\base\().\length.endm`Use the alternate macro syntax mode'In the alternative macro syntax mode the ampersand character(`&') can be used as a separator. eg:.altmacro.macro label ll&:.endmNote: this problem of correctly identifying string parameters topseudo ops also applies to the identifiers used in `.irp' (*noteIrp::) and `.irpc' (*note Irpc::) as well.`.endm'Mark the end of a macro definition.`.exitm'Exit early from the current macro definition.`\@'`as' maintains a counter of how many macros it has executed inthis pseudo-variable; you can copy that number to your output with`\@', but _only within a macro definition_.`LOCAL NAME [ , ... ]'_Warning: `LOCAL' is only available if you select "alternate macrosyntax" with `--alternate' or `.altmacro'._ *Note `.altmacro':Altmacro.File: as.info, Node: Altmacro, Next: Ascii, Prev: Align, Up: Pseudo Ops7.77 `.altmacro'================Enable alternate macro mode, enabling:`LOCAL NAME [ , ... ]'One additional directive, `LOCAL', is available. It is used togenerate a string replacement for each of the NAME arguments, andreplace any instances of NAME in each macro expansion. Thereplacement string is unique in the assembly, and different foreach separate macro expansion. `LOCAL' allows you to write macrosthat define symbols, without fear of conflict between separatemacro expansions.`String delimiters'You can write strings delimited in these other ways besides`"STRING"':`'STRING''You can delimit strings with single-quote characters.`<STRING>'You can delimit strings with matching angle brackets.`single-character string escape'To include any single character literally in a string (even if thecharacter would otherwise have some special meaning), you canprefix the character with `!' (an exclamation mark). For example,you can write `<4.3 !> 5.4!!>' to get the literal text `4.3 >5.4!'.`Expression results as strings'You can write `%EXPR' to evaluate the expression EXPR and use theresult as a string.File: as.info, Node: Noaltmacro, Next: Nolist, Prev: MRI, Up: Pseudo Ops7.78 `.noaltmacro'==================Disable alternate macro mode. *Note Altmacro::.File: as.info, Node: Nolist, Next: Octa, Prev: Noaltmacro, Up: Pseudo Ops7.79 `.nolist'==============Control (in conjunction with the `.list' directive) whether or notassembly listings are generated. These two directives maintain aninternal counter (which is zero initially). `.list' increments thecounter, and `.nolist' decrements it. Assembly listings are generatedwhenever the counter is greater than zero.File: as.info, Node: Octa, Next: Org, Prev: Nolist, Up: Pseudo Ops7.80 `.octa BIGNUMS'====================This directive expects zero or more bignums, separated by commas. Foreach bignum, it emits a 16-byte integer.The term "octa" comes from contexts in which a "word" is two bytes;hence _octa_-word for 16 bytes.File: as.info, Node: Org, Next: P2align, Prev: Octa, Up: Pseudo Ops7.81 `.org NEW-LC , FILL'=========================Advance the location counter of the current section to NEW-LC. NEW-LCis either an absolute expression or an expression with the same sectionas the current subsection. That is, you can't use `.org' to crosssections: if NEW-LC has the wrong section, the `.org' directive isignored. To be compatible with former assemblers, if the section ofNEW-LC is absolute, `as' issues a warning, then pretends the section ofNEW-LC is the same as the current subsection.`.org' may only increase the location counter, or leave itunchanged; you cannot use `.org' to move the location counter backwards.Because `as' tries to assemble programs in one pass, NEW-LC may notbe undefined. If you really detest this restriction we eagerly await achance to share your improved assembler.Beware that the origin is relative to the start of the section, notto the start of the subsection. This is compatible with other people'sassemblers.When the location counter (of the current subsection) is advanced,the intervening bytes are filled with FILL which should be an absoluteexpression. If the comma and FILL are omitted, FILL defaults to zero.File: as.info, Node: P2align, Next: PopSection, Prev: Org, Up: Pseudo Ops7.82 `.p2align[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'================================================Pad the location counter (in the current subsection) to a particularstorage boundary. The first expression (which must be absolute) is thenumber of low-order zero bits the location counter must have afteradvancement. For example `.p2align 3' advances the location counteruntil it a multiple of 8. If the location counter is already amultiple of 8, no change is needed.The second expression (also absolute) gives the fill value to bestored in the padding bytes. It (and the comma) may be omitted. If itis omitted, the padding bytes are normally zero. However, on somesystems, if the section is marked as containing code and the fill valueis omitted, the space is filled with no-op instructions.The third expression is also absolute, and is also optional. If itis present, it is the maximum number of bytes that should be skipped bythis alignment directive. If doing the alignment would requireskipping more bytes than the specified maximum, then the alignment isnot done at all. You can omit the fill value (the second argument)entirely by simply using two commas after the required alignment; thiscan be useful if you want the alignment to be filled with no-opinstructions when appropriate.The `.p2alignw' and `.p2alignl' directives are variants of the`.p2align' directive. The `.p2alignw' directive treats the fillpattern as a two byte word value. The `.p2alignl' directives treats thefill pattern as a four byte longword value. For example, `.p2alignw2,0x368d' will align to a multiple of 4. If it skips two bytes, theywill be filled in with the value 0x368d (the exact placement of thebytes depends upon the endianness of the processor). If it skips 1 or3 bytes, the fill value is undefined.File: as.info, Node: Previous, Next: Print, Prev: PopSection, Up: Pseudo Ops7.83 `.previous'================This is one of the ELF section stack manipulation directives. Theothers are `.section' (*note Section::), `.subsection' (*noteSubSection::), `.pushsection' (*note PushSection::), and `.popsection'(*note PopSection::).This directive swaps the current section (and subsection) with mostrecently referenced section/subsection pair prior to this one. Multiple`.previous' directives in a row will flip between two sections (andtheir subsections). For example:.section A.subsection 1.word 0x1234.subsection 2.word 0x5678.previous.word 0x9abcWill place 0x1234 and 0x9abc into subsection 1 and 0x5678 intosubsection 2 of section A. Whilst:.section A.subsection 1# Now in section A subsection 1.word 0x1234.section B.subsection 0# Now in section B subsection 0.word 0x5678.subsection 1# Now in section B subsection 1.word 0x9abc.previous# Now in section B subsection 0.word 0xdef0Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection0 of section B and 0x9abc into subsection 1 of section B.In terms of the section stack, this directive swaps the currentsection with the top section on the section stack.File: as.info, Node: PopSection, Next: Previous, Prev: P2align, Up: Pseudo Ops7.84 `.popsection'==================This is one of the ELF section stack manipulation directives. Theothers are `.section' (*note Section::), `.subsection' (*noteSubSection::), `.pushsection' (*note PushSection::), and `.previous'(*note Previous::).This directive replaces the current section (and subsection) withthe top section (and subsection) on the section stack. This section ispopped off the stack.File: as.info, Node: Print, Next: Protected, Prev: Previous, Up: Pseudo Ops7.85 `.print STRING'====================`as' will print STRING on the standard output during assembly. Youmust put STRING in double quotes.File: as.info, Node: Protected, Next: Psize, Prev: Print, Up: Pseudo Ops7.86 `.protected NAMES'=======================This is one of the ELF visibility directives. The other two are`.hidden' (*note Hidden::) and `.internal' (*note Internal::).This directive overrides the named symbols default visibility (whichis set by their binding: local, global or weak). The directive setsthe visibility to `protected' which means that any references to thesymbols from within the components that defines them must be resolvedto the definition in that component, even if a definition in anothercomponent would normally preempt this.File: as.info, Node: Psize, Next: Purgem, Prev: Protected, Up: Pseudo Ops7.87 `.psize LINES , COLUMNS'=============================Use this directive to declare the number of lines--and, optionally, thenumber of columns--to use for each page, when generating listings.If you do not use `.psize', listings use a default line-count of 60.You may omit the comma and COLUMNS specification; the default width is200 columns.`as' generates formfeeds whenever the specified number of lines isexceeded (or whenever you explicitly request one, using `.eject').If you specify LINES as `0', no formfeeds are generated save thoseexplicitly specified with `.eject'.File: as.info, Node: Purgem, Next: PushSection, Prev: Psize, Up: Pseudo Ops7.88 `.purgem NAME'===================Undefine the macro NAME, so that later uses of the string will not beexpanded. *Note Macro::.File: as.info, Node: PushSection, Next: Quad, Prev: Purgem, Up: Pseudo Ops7.89 `.pushsection NAME [, SUBSECTION] [, "FLAGS"[, @TYPE[,ARGUMENTS]]]'========================================================================This is one of the ELF section stack manipulation directives. Theothers are `.section' (*note Section::), `.subsection' (*noteSubSection::), `.popsection' (*note PopSection::), and `.previous'(*note Previous::).This directive pushes the current section (and subsection) onto thetop of the section stack, and then replaces the current section andsubsection with `name' and `subsection'. The optional `flags', `type'and `arguments' are treated the same as in the `.section' (*noteSection::) directive.File: as.info, Node: Quad, Next: Reloc, Prev: PushSection, Up: Pseudo Ops7.90 `.quad BIGNUMS'====================`.quad' expects zero or more bignums, separated by commas. For eachbignum, it emits an 8-byte integer. If the bignum won't fit in 8bytes, it prints a warning message; and just takes the lowest order 8bytes of the bignum.The term "quad" comes from contexts in which a "word" is two bytes;hence _quad_-word for 8 bytes.File: as.info, Node: Reloc, Next: Rept, Prev: Quad, Up: Pseudo Ops7.91 `.reloc OFFSET, RELOC_NAME[, EXPRESSION]'==============================================Generate a relocation at OFFSET of type RELOC_NAME with valueEXPRESSION. If OFFSET is a number, the relocation is generated in thecurrent section. If OFFSET is an expression that resolves to a symbolplus offset, the relocation is generated in the given symbol's section.EXPRESSION, if present, must resolve to a symbol plus addend or to anabsolute value, but note that not all targets support an addend. e.g.ELF REL targets such as i386 store an addend in the section contentsrather than in the relocation. This low level interface does notsupport addends stored in the section.File: as.info, Node: Rept, Next: Sbttl, Prev: Reloc, Up: Pseudo Ops7.92 `.rept COUNT'==================Repeat the sequence of lines between the `.rept' directive and the next`.endr' directive COUNT times.For example, assembling.rept 3.long 0.endris equivalent to assembling.long 0.long 0.long 0File: as.info, Node: Sbttl, Next: Scl, Prev: Rept, Up: Pseudo Ops7.93 `.sbttl "SUBHEADING"'==========================Use SUBHEADING as the title (third line, immediately after the titleline) when generating assembly listings.This directive affects subsequent pages, as well as the current pageif it appears within ten lines of the top of a page.File: as.info, Node: Scl, Next: Section, Prev: Sbttl, Up: Pseudo Ops7.94 `.scl CLASS'=================Set the storage-class value for a symbol. This directive may only beused inside a `.def'/`.endef' pair. Storage class may flag whether asymbol is static or external, or it may record further symbolicdebugging information.File: as.info, Node: Section, Next: Set, Prev: Scl, Up: Pseudo Ops7.95 `.section NAME'====================Use the `.section' directive to assemble the following code into asection named NAME.This directive is only supported for targets that actually supportarbitrarily named sections; on `a.out' targets, for example, it is notaccepted, even with a standard `a.out' section name.COFF Version------------For COFF targets, the `.section' directive is used in one of thefollowing ways:.section NAME[, "FLAGS"].section NAME[, SUBSECTION]If the optional argument is quoted, it is taken as flags to use forthe section. Each flag is a single character. The following flags arerecognized:`b'bss section (uninitialized data)`n'section is not loaded`w'writable section`d'data section`r'read-only section`x'executable section`s'shared section (meaningful for PE targets)`a'ignored. (For compatibility with the ELF version)If no flags are specified, the default flags depend upon the sectionname. If the section name is not recognized, the default will be forthe section to be loaded and writable. Note the `n' and `w' flagsremove attributes from the section, rather than adding them, so if theyare used on their own it will be as if no flags had been specified atall.If the optional argument to the `.section' directive is not quoted,it is taken as a subsection number (*note Sub-Sections::).ELF Version-----------This is one of the ELF section stack manipulation directives. Theothers are `.subsection' (*note SubSection::), `.pushsection' (*notePushSection::), `.popsection' (*note PopSection::), and `.previous'(*note Previous::).For ELF targets, the `.section' directive is used like this:.section NAME [, "FLAGS"[, @TYPE[,FLAG_SPECIFIC_ARGUMENTS]]]The optional FLAGS argument is a quoted string which may contain anycombination of the following characters:`a'section is allocatable`w'section is writable`x'section is executable`M'section is mergeable`S'section contains zero terminated strings`G'section is a member of a section group`T'section is used for thread-local-storageThe optional TYPE argument may contain one of the followingconstants:`@progbits'section contains data`@nobits'section does not contain data (i.e., section only occupies space)`@note'section contains data which is used by things other than theprogram`@init_array'section contains an array of pointers to init functions`@fini_array'section contains an array of pointers to finish functions`@preinit_array'section contains an array of pointers to pre-init functionsMany targets only support the first three section types.Note on targets where the `@' character is the start of a comment (egARM) then another character is used instead. For example the ARM portuses the `%' character.If FLAGS contains the `M' symbol then the TYPE argument must bespecified as well as an extra argument--ENTSIZE--like this:.section NAME , "FLAGS"M, @TYPE, ENTSIZESections with the `M' flag but not `S' flag must contain fixed sizeconstants, each ENTSIZE octets long. Sections with both `M' and `S'must contain zero terminated strings where each character is ENTSIZEbytes long. The linker may remove duplicates within sections with thesame name, same entity size and same flags. ENTSIZE must be anabsolute expression.If FLAGS contains the `G' symbol then the TYPE argument must bepresent along with an additional field like this:.section NAME , "FLAGS"G, @TYPE, GROUPNAME[, LINKAGE]The GROUPNAME field specifies the name of the section group to whichthis particular section belongs. The optional linkage field cancontain:`comdat'indicates that only one copy of this section should be retained`.gnu.linkonce'an alias for comdatNote: if both the M and G flags are present then the fields for theMerge flag should come first, like this:.section NAME , "FLAGS"MG, @TYPE, ENTSIZE, GROUPNAME[, LINKAGE]If no flags are specified, the default flags depend upon the sectionname. If the section name is not recognized, the default will be forthe section to have none of the above flags: it will not be allocatedin memory, nor writable, nor executable. The section will contain data.For ELF targets, the assembler supports another type of `.section'directive for compatibility with the Solaris assembler:.section "NAME"[, FLAGS...]Note that the section name is quoted. There may be a sequence ofcomma separated flags:`#alloc'section is allocatable`#write'section is writable`#execinstr'section is executable`#tls'section is used for thread local storageThis directive replaces the current section and subsection. See thecontents of the gas testsuite directory `gas/testsuite/gas/elf' forsome examples of how this directive and the other section stackdirectives work.File: as.info, Node: Set, Next: Short, Prev: Section, Up: Pseudo Ops7.96 `.set SYMBOL, EXPRESSION'==============================Set the value of SYMBOL to EXPRESSION. This changes SYMBOL's value andtype to conform to EXPRESSION. If SYMBOL was flagged as external, itremains flagged (*note Symbol Attributes::).You may `.set' a symbol many times in the same assembly.If you `.set' a global symbol, the value stored in the object fileis the last value stored into it.The syntax for `set' on the HPPA is `SYMBOL .set EXPRESSION'.On Z80 `set' is a real instruction, use `SYMBOL defl EXPRESSION'instead.File: as.info, Node: Short, Next: Single, Prev: Set, Up: Pseudo Ops7.97 `.short EXPRESSIONS'=========================`.short' is normally the same as `.word'. *Note `.word': Word.In some configurations, however, `.short' and `.word' generatenumbers of different lengths. *Note Machine Dependencies::.File: as.info, Node: Single, Next: Size, Prev: Short, Up: Pseudo Ops7.98 `.single FLONUMS'======================This directive assembles zero or more flonums, separated by commas. Ithas the same effect as `.float'. The exact kind of floating pointnumbers emitted depends on how `as' is configured. *Note MachineDependencies::.File: as.info, Node: Size, Next: Skip, Prev: Single, Up: Pseudo Ops7.99 `.size'============This directive is used to set the size associated with a symbol.COFF Version------------For COFF targets, the `.size' directive is only permitted inside`.def'/`.endef' pairs. It is used like this:.size EXPRESSIONELF Version-----------For ELF targets, the `.size' directive is used like this:.size NAME , EXPRESSIONThis directive sets the size associated with a symbol NAME. Thesize in bytes is computed from EXPRESSION which can make use of labelarithmetic. This directive is typically used to set the size offunction symbols.File: as.info, Node: Sleb128, Next: Space, Prev: Skip, Up: Pseudo Ops7.100 `.sleb128 EXPRESSIONS'============================SLEB128 stands for "signed little endian base 128." This is a compact,variable length representation of numbers used by the DWARF symbolicdebugging format. *Note `.uleb128': Uleb128.File: as.info, Node: Skip, Next: Sleb128, Prev: Size, Up: Pseudo Ops7.101 `.skip SIZE , FILL'=========================This directive emits SIZE bytes, each of value FILL. Both SIZE andFILL are absolute expressions. If the comma and FILL are omitted, FILLis assumed to be zero. This is the same as `.space'.File: as.info, Node: Space, Next: Stab, Prev: Sleb128, Up: Pseudo Ops7.102 `.space SIZE , FILL'==========================This directive emits SIZE bytes, each of value FILL. Both SIZE andFILL are absolute expressions. If the comma and FILL are omitted, FILLis assumed to be zero. This is the same as `.skip'._Warning:_ `.space' has a completely different meaning for HPPAtargets; use `.block' as a substitute. See `HP9000 Series 800Assembly Language Reference Manual' (HP 92432-90001) for themeaning of the `.space' directive. *Note HPPA AssemblerDirectives: HPPA Directives, for a summary.File: as.info, Node: Stab, Next: String, Prev: Space, Up: Pseudo Ops7.103 `.stabd, .stabn, .stabs'==============================There are three directives that begin `.stab'. All emit symbols (*noteSymbols::), for use by symbolic debuggers. The symbols are not enteredin the `as' hash table: they cannot be referenced elsewhere in thesource file. Up to five fields are required:STRINGThis is the symbol's name. It may contain any character except`\000', so is more general than ordinary symbol names. Somedebuggers used to code arbitrarily complex structures into symbolnames using this field.TYPEAn absolute expression. The symbol's type is set to the low 8bits of this expression. Any bit pattern is permitted, but `ld'and debuggers choke on silly bit patterns.OTHERAn absolute expression. The symbol's "other" attribute is set tothe low 8 bits of this expression.DESCAn absolute expression. The symbol's descriptor is set to the low16 bits of this expression.VALUEAn absolute expression which becomes the symbol's value.If a warning is detected while reading a `.stabd', `.stabn', or`.stabs' statement, the symbol has probably already been created; youget a half-formed symbol in your object file. This is compatible withearlier assemblers!`.stabd TYPE , OTHER , DESC'The "name" of the symbol generated is not even an empty string.It is a null pointer, for compatibility. Older assemblers used anull pointer so they didn't waste space in object files with emptystrings.The symbol's value is set to the location counter, relocatably.When your program is linked, the value of this symbol is theaddress of the location counter when the `.stabd' was assembled.`.stabn TYPE , OTHER , DESC , VALUE'The name of the symbol is set to the empty string `""'.`.stabs STRING , TYPE , OTHER , DESC , VALUE'All five fields are specified.File: as.info, Node: String, Next: Struct, Prev: Stab, Up: Pseudo Ops7.104 `.string' "STR", `.string8' "STR", `.string16'===================================================="STR", `.string32' "STR", `.string64' "STR"Copy the characters in STR to the object file. You may specify morethan one string to copy, separated by commas. Unless otherwisespecified for a particular machine, the assembler marks the end of eachstring with a 0 byte. You can use any of the escape sequencesdescribed in *Note Strings: Strings.The variants `string16', `string32' and `string64' differ from the`string' pseudo opcode in that each 8-bit character from STR is copiedand expanded to 16, 32 or 64 bits respectively. The expanded charactersare stored in target endianness byte order.Example:.string32 "BYE"expands to:.string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */.string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */File: as.info, Node: Struct, Next: SubSection, Prev: String, Up: Pseudo Ops7.105 `.struct EXPRESSION'==========================Switch to the absolute section, and set the section offset toEXPRESSION, which must be an absolute expression. You might use thisas follows:.struct 0field1:.struct field1 + 4field2:.struct field2 + 4field3:This would define the symbol `field1' to have the value 0, the symbol`field2' to have the value 4, and the symbol `field3' to have the value8. Assembly would be left in the absolute section, and you would needto use a `.section' directive of some sort to change to some othersection before further assembly.File: as.info, Node: SubSection, Next: Symver, Prev: Struct, Up: Pseudo Ops7.106 `.subsection NAME'========================This is one of the ELF section stack manipulation directives. Theothers are `.section' (*note Section::), `.pushsection' (*notePushSection::), `.popsection' (*note PopSection::), and `.previous'(*note Previous::).This directive replaces the current subsection with `name'. Thecurrent section is not changed. The replaced subsection is put ontothe section stack in place of the then current top of stack subsection.File: as.info, Node: Symver, Next: Tag, Prev: SubSection, Up: Pseudo Ops7.107 `.symver'===============Use the `.symver' directive to bind symbols to specific version nodeswithin a source file. This is only supported on ELF platforms, and istypically used when assembling files to be linked into a shared library.There are cases where it may make sense to use this in objects to bebound into an application itself so as to override a versioned symbolfrom a shared library.For ELF targets, the `.symver' directive can be used like this:.symver NAME, NAME2@NODENAMEIf the symbol NAME is defined within the file being assembled, the`.symver' directive effectively creates a symbol alias with the nameNAME2@NODENAME, and in fact the main reason that we just don't try andcreate a regular alias is that the @ character isn't permitted insymbol names. The NAME2 part of the name is the actual name of thesymbol by which it will be externally referenced. The name NAME itselfis merely a name of convenience that is used so that it is possible tohave definitions for multiple versions of a function within a singlesource file, and so that the compiler can unambiguously know whichversion of a function is being mentioned. The NODENAME portion of thealias should be the name of a node specified in the version scriptsupplied to the linker when building a shared library. If you areattempting to override a versioned symbol from a shared library, thenNODENAME should correspond to the nodename of the symbol you are tryingto override.If the symbol NAME is not defined within the file being assembled,all references to NAME will be changed to NAME2@NODENAME. If noreference to NAME is made, NAME2@NODENAME will be removed from thesymbol table.Another usage of the `.symver' directive is:.symver NAME, NAME2@@NODENAMEIn this case, the symbol NAME must exist and be defined within thefile being assembled. It is similar to NAME2@NODENAME. The differenceis NAME2@@NODENAME will also be used to resolve references to NAME2 bythe linker.The third usage of the `.symver' directive is:.symver NAME, NAME2@@@NODENAMEWhen NAME is not defined within the file being assembled, it istreated as NAME2@NODENAME. When NAME is defined within the file beingassembled, the symbol name, NAME, will be changed to NAME2@@NODENAME.File: as.info, Node: Tag, Next: Text, Prev: Symver, Up: Pseudo Ops7.108 `.tag STRUCTNAME'=======================This directive is generated by compilers to include auxiliary debugginginformation in the symbol table. It is only permitted inside`.def'/`.endef' pairs. Tags are used to link structure definitions inthe symbol table with instances of those structures.File: as.info, Node: Text, Next: Title, Prev: Tag, Up: Pseudo Ops7.109 `.text SUBSECTION'========================Tells `as' to assemble the following statements onto the end of thetext subsection numbered SUBSECTION, which is an absolute expression.If SUBSECTION is omitted, subsection number zero is used.File: as.info, Node: Title, Next: Type, Prev: Text, Up: Pseudo Ops7.110 `.title "HEADING"'========================Use HEADING as the title (second line, immediately after the sourcefile name and pagenumber) when generating assembly listings.This directive affects subsequent pages, as well as the current pageif it appears within ten lines of the top of a page.File: as.info, Node: Type, Next: Uleb128, Prev: Title, Up: Pseudo Ops7.111 `.type'=============This directive is used to set the type of a symbol.COFF Version------------For COFF targets, this directive is permitted only within`.def'/`.endef' pairs. It is used like this:.type INTThis records the integer INT as the type attribute of a symbol tableentry.ELF Version-----------For ELF targets, the `.type' directive is used like this:.type NAME , TYPE DESCRIPTIONThis sets the type of symbol NAME to be either a function symbol oran object symbol. There are five different syntaxes supported for theTYPE DESCRIPTION field, in order to provide compatibility with variousother assemblers.Because some of the characters used in these syntaxes (such as `@'and `#') are comment characters for some architectures, some of thesyntaxes below do not work on all architectures. The first variantwill be accepted by the GNU assembler on all architectures so thatvariant should be used for maximum portability, if you do not need toassemble your code with other assemblers.The syntaxes supported are:.type <name> STT_<TYPE_IN_UPPER_CASE>.type <name>,#<type>.type <name>,@<type>.type <name>,%>type>.type <name>,"<type>"The types supported are:`STT_FUNC'`function'Mark the symbol as being a function name.`STT_OBJECT'`object'Mark the symbol as being a data object.`STT_TLS'`tls_object'Mark the symbol as being a thead-local data object.`STT_COMMON'`common'Mark the symbol as being a common data object.Note: Some targets support extra types in addition to those listedabove.File: as.info, Node: Uleb128, Next: Val, Prev: Type, Up: Pseudo Ops7.112 `.uleb128 EXPRESSIONS'============================ULEB128 stands for "unsigned little endian base 128." This is acompact, variable length representation of numbers used by the DWARFsymbolic debugging format. *Note `.sleb128': Sleb128.File: as.info, Node: Val, Next: Version, Prev: Uleb128, Up: Pseudo Ops7.113 `.val ADDR'=================This directive, permitted only within `.def'/`.endef' pairs, recordsthe address ADDR as the value attribute of a symbol table entry.File: as.info, Node: Version, Next: VTableEntry, Prev: Val, Up: Pseudo Ops7.114 `.version "STRING"'=========================This directive creates a `.note' section and places into it an ELFformatted note of type NT_VERSION. The note's name is set to `string'.File: as.info, Node: VTableEntry, Next: VTableInherit, Prev: Version, Up: Pseudo Ops7.115 `.vtable_entry TABLE, OFFSET'===================================This directive finds or creates a symbol `table' and creates a`VTABLE_ENTRY' relocation for it with an addend of `offset'.File: as.info, Node: VTableInherit, Next: Warning, Prev: VTableEntry, Up: Pseudo Ops7.116 `.vtable_inherit CHILD, PARENT'=====================================This directive finds the symbol `child' and finds or creates the symbol`parent' and then creates a `VTABLE_INHERIT' relocation for the parentwhose addend is the value of the child symbol. As a special case theparent name of `0' is treated as referring to the `*ABS*' section.File: as.info, Node: Warning, Next: Weak, Prev: VTableInherit, Up: Pseudo Ops7.117 `.warning "STRING"'=========================Similar to the directive `.error' (*note `.error "STRING"': Error.),but just emits a warning.File: as.info, Node: Weak, Next: Weakref, Prev: Warning, Up: Pseudo Ops7.118 `.weak NAMES'===================This directive sets the weak attribute on the comma separated list ofsymbol `names'. If the symbols do not already exist, they will becreated.On COFF targets other than PE, weak symbols are a GNU extension.This directive sets the weak attribute on the comma separated list ofsymbol `names'. If the symbols do not already exist, they will becreated.On the PE target, weak symbols are supported natively as weakaliases. When a weak symbol is created that is not an alias, GAScreates an alternate symbol to hold the default value.File: as.info, Node: Weakref, Next: Word, Prev: Weak, Up: Pseudo Ops7.119 `.weakref ALIAS, TARGET'==============================This directive creates an alias to the target symbol that enables thesymbol to be referenced with weak-symbol semantics, but withoutactually making it weak. If direct references or definitions of thesymbol are present, then the symbol will not be weak, but if allreferences to it are through weak references, the symbol will be markedas weak in the symbol table.The effect is equivalent to moving all references to the alias to aseparate assembly source file, renaming the alias to the symbol in it,declaring the symbol as weak there, and running a reloadable link tomerge the object files resulting from the assembly of the new sourcefile and the old source file that had the references to the aliasremoved.The alias itself never makes to the symbol table, and is entirelyhandled within the assembler.File: as.info, Node: Word, Next: Deprecated, Prev: Weakref, Up: Pseudo Ops7.120 `.word EXPRESSIONS'=========================This directive expects zero or more EXPRESSIONS, of any section,separated by commas.The size of the number emitted, and its byte order, depend on whattarget computer the assembly is for._Warning: Special Treatment to support Compilers_Machines with a 32-bit address space, but that do less than 32-bitaddressing, require the following special treatment. If the machine ofinterest to you does 32-bit addressing (or doesn't require it; *noteMachine Dependencies::), you can ignore this issue.In order to assemble compiler output into something that works, `as'occasionally does strange things to `.word' directives. Directives ofthe form `.word sym1-sym2' are often emitted by compilers as part ofjump tables. Therefore, when `as' assembles a directive of the form`.word sym1-sym2', and the difference between `sym1' and `sym2' doesnot fit in 16 bits, `as' creates a "secondary jump table", immediatelybefore the next label. This secondary jump table is preceded by ashort-jump to the first byte after the secondary table. Thisshort-jump prevents the flow of control from accidentally falling intothe new table. Inside the table is a long-jump to `sym2'. Theoriginal `.word' contains `sym1' minus the address of the long-jump to`sym2'.If there were several occurrences of `.word sym1-sym2' before thesecondary jump table, all of them are adjusted. If there was a `.wordsym3-sym4', that also did not fit in sixteen bits, a long-jump to`sym4' is included in the secondary jump table, and the `.word'directives are adjusted to contain `sym3' minus the address of thelong-jump to `sym4'; and so on, for as many entries in the originaljump table as necessary.File: as.info, Node: Deprecated, Prev: Word, Up: Pseudo Ops7.121 Deprecated Directives===========================One day these directives won't work. They are included forcompatibility with older assemblers..abort.lineFile: as.info, Node: Object Attributes, Next: Machine Dependencies, Prev: Pseudo Ops, Up: Top8 Object Attributes*******************`as' assembles source files written for a specific architecture intoobject files for that architecture. But not all object files are alike.Many architectures support incompatible variations. For instance,floating point arguments might be passed in floating point registers ifthe object file requires hardware floating point support--or floatingpoint arguments might be passed in integer registers if the object filesupports processors with no hardware floating point unit. Or, if twoobjects are built for different generations of the same architecture,the combination may require the newer generation at run-time.This information is useful during and after linking. At link time,`ld' can warn about incompatible object files. After link time, toolslike `gdb' can use it to process the linked file correctly.Compatibility information is recorded as a series of objectattributes. Each attribute has a "vendor", "tag", and "value". Thevendor is a string, and indicates who sets the meaning of the tag. Thetag is an integer, and indicates what property the attribute describes.The value may be a string or an integer, and indicates how theproperty affects this object. Missing attributes are the same asattributes with a zero value or empty string value.Object attributes were developed as part of the ABI for the ARMArchitecture. The file format is documented in `ELF for the ARMArchitecture'.* Menu:* GNU Object Attributes:: GNU Object Attributes* Defining New Object Attributes:: Defining New Object AttributesFile: as.info, Node: GNU Object Attributes, Next: Defining New Object Attributes, Up: Object Attributes8.1 GNU Object Attributes=========================The `.gnu_attribute' directive records an object attribute with vendor`gnu'.Except for `Tag_compatibility', which has both an integer and astring for its value, GNU attributes have a string value if the tagnumber is odd and an integer value if the tag number is even. Thesecond bit (`TAG & 2' is set for architecture-independent attributesand clear for architecture-dependent ones.8.1.1 Common GNU attributes---------------------------These attributes are valid on all architectures.Tag_compatibility (32)The compatibility attribute takes an integer flag value and avendor name. If the flag value is 0, the file is compatible withother toolchains. If it is 1, then the file is only compatiblewith the named toolchain. If it is greater than 1, the file canonly be processed by other toolchains under some privatearrangement indicated by the flag value and the vendor name.8.1.2 MIPS Attributes---------------------Tag_GNU_MIPS_ABI_FP (4)The floating-point ABI used by this object file. The value willbe:* 0 for files not affected by the floating-point ABI.* 1 for files using the hardware floating-point with a standarddouble-precision FPU.* 2 for files using the hardware floating-point ABI with asingle-precision FPU.* 3 for files using the software floating-point ABI.* 4 for files using the hardware floating-point ABI with 64-bitwide double-precision floating-point registers and 32-bitwide general purpose registers.8.1.3 PowerPC Attributes------------------------Tag_GNU_Power_ABI_FP (4)The floating-point ABI used by this object file. The value willbe:* 0 for files not affected by the floating-point ABI.* 1 for files using double-precision hardware floating-pointABI.* 2 for files using the software floating-point ABI.* 3 for files using single-precision hardware floating-pointABI.Tag_GNU_Power_ABI_Vector (8)The vector ABI used by this object file. The value will be:* 0 for files not affected by the vector ABI.* 1 for files using general purpose registers to pass vectors.* 2 for files using AltiVec registers to pass vectors.* 3 for files using SPE registers to pass vectors.File: as.info, Node: Defining New Object Attributes, Prev: GNU Object Attributes, Up: Object Attributes8.2 Defining New Object Attributes==================================If you want to define a new GNU object attribute, here are the placesyou will need to modify. New attributes should be discussed on the`binutils' mailing list.* This manual, which is the official register of attributes.* The header for your architecture `include/elf', to define the tag.* The `bfd' support file for your architecture, to merge theattribute and issue any appropriate link warnings.* Test cases in `ld/testsuite' for merging and link warnings.* `binutils/readelf.c' to display your attribute.* GCC, if you want the compiler to mark the attribute automatically.File: as.info, Node: Machine Dependencies, Next: Reporting Bugs, Prev: Object Attributes, Up: Top9 Machine Dependent Features****************************The machine instruction sets are (almost by definition) different oneach machine where `as' runs. Floating point representations vary aswell, and `as' often supports a few additional directives orcommand-line options for compatibility with other assemblers on aparticular platform. Finally, some versions of `as' support specialpseudo-instructions for branch optimization.This chapter discusses most of these differences, though it does notinclude details on any machine's instruction set. For details on thatsubject, see the hardware manufacturer's manual.* Menu:* Alpha-Dependent:: Alpha Dependent Features* ARC-Dependent:: ARC Dependent Features* ARM-Dependent:: ARM Dependent Features* AVR-Dependent:: AVR Dependent Features* BFIN-Dependent:: BFIN Dependent Features* CR16-Dependent:: CR16 Dependent Features* CRIS-Dependent:: CRIS Dependent Features* D10V-Dependent:: D10V Dependent Features* D30V-Dependent:: D30V Dependent Features* H8/300-Dependent:: Renesas H8/300 Dependent Features* HPPA-Dependent:: HPPA Dependent Features* ESA/390-Dependent:: IBM ESA/390 Dependent Features* i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features* i860-Dependent:: Intel 80860 Dependent Features* i960-Dependent:: Intel 80960 Dependent Features* IA-64-Dependent:: Intel IA-64 Dependent Features* IP2K-Dependent:: IP2K Dependent Features* M32C-Dependent:: M32C Dependent Features* M32R-Dependent:: M32R Dependent Features* M68K-Dependent:: M680x0 Dependent Features* M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features* MIPS-Dependent:: MIPS Dependent Features* MMIX-Dependent:: MMIX Dependent Features* MSP430-Dependent:: MSP430 Dependent Features* SH-Dependent:: Renesas / SuperH SH Dependent Features* SH64-Dependent:: SuperH SH64 Dependent Features* PDP-11-Dependent:: PDP-11 Dependent Features* PJ-Dependent:: picoJava Dependent Features* PPC-Dependent:: PowerPC Dependent Features* Sparc-Dependent:: SPARC Dependent Features* TIC54X-Dependent:: TI TMS320C54x Dependent Features* V850-Dependent:: V850 Dependent Features* Xtensa-Dependent:: Xtensa Dependent Features* Z80-Dependent:: Z80 Dependent Features* Z8000-Dependent:: Z8000 Dependent Features* Vax-Dependent:: VAX Dependent FeaturesFile: as.info, Node: Alpha-Dependent, Next: ARC-Dependent, Up: Machine Dependencies9.1 Alpha Dependent Features============================* Menu:* Alpha Notes:: Notes* Alpha Options:: Options* Alpha Syntax:: Syntax* Alpha Floating Point:: Floating Point* Alpha Directives:: Alpha Machine Directives* Alpha Opcodes:: OpcodesFile: as.info, Node: Alpha Notes, Next: Alpha Options, Up: Alpha-Dependent9.1.1 Notes-----------The documentation here is primarily for the ELF object format. `as'also supports the ECOFF and EVAX formats, but features specific tothese formats are not yet documented.File: as.info, Node: Alpha Options, Next: Alpha Syntax, Prev: Alpha Notes, Up: Alpha-Dependent9.1.2 Options-------------`-mCPU'This option specifies the target processor. If an attempt is madeto assemble an instruction which will not execute on the targetprocessor, the assembler may either expand the instruction as amacro or issue an error message. This option is equivalent to the`.arch' directive.The following processor names are recognized: `21064', `21064a',`21066', `21068', `21164', `21164a', `21164pc', `21264', `21264a',`21264b', `ev4', `ev5', `lca45', `ev5', `ev56', `pca56', `ev6',`ev67', `ev68'. The special name `all' may be used to allow theassembler to accept instructions valid for any Alpha processor.In order to support existing practice in OSF/1 with respect to`.arch', and existing practice within `MILO' (the Linux ARCbootloader), the numbered processor names (e.g. 21064) enable theprocessor-specific PALcode instructions, while the"electro-vlasic" names (e.g. `ev4') do not.`-mdebug'`-no-mdebug'Enables or disables the generation of `.mdebug' encapsulation forstabs directives and procedure descriptors. The default is toautomatically enable `.mdebug' when the first stabs directive isseen.`-relax'This option forces all relocations to be put into the object file,instead of saving space and resolving some relocations at assemblytime. Note that this option does not propagate all symbolarithmetic into the object file, because not all symbol arithmeticcan be represented. However, the option can still be useful inspecific applications.`-g'This option is used when the compiler generates debug information.When `gcc' is using `mips-tfile' to generate debug informationfor ECOFF, local labels must be passed through to the object file.Otherwise this option has no effect.`-GSIZE'A local common symbol larger than SIZE is placed in `.bss', whilesmaller symbols are placed in `.sbss'.`-F'`-32addr'These options are ignored for backward compatibility.File: as.info, Node: Alpha Syntax, Next: Alpha Floating Point, Prev: Alpha Options, Up: Alpha-Dependent9.1.3 Syntax------------The assembler syntax closely follow the Alpha Reference Manual;assembler directives and general syntax closely follow the OSF/1 andOpenVMS syntax, with a few differences for ELF.* Menu:* Alpha-Chars:: Special Characters* Alpha-Regs:: Register Names* Alpha-Relocs:: RelocationsFile: as.info, Node: Alpha-Chars, Next: Alpha-Regs, Up: Alpha Syntax9.1.3.1 Special Characters..........................`#' is the line comment character.`;' can be used instead of a newline to separate statements.File: as.info, Node: Alpha-Regs, Next: Alpha-Relocs, Prev: Alpha-Chars, Up: Alpha Syntax9.1.3.2 Register Names......................The 32 integer registers are referred to as `$N' or `$rN'. Inaddition, registers 15, 28, 29, and 30 may be referred to by thesymbols `$fp', `$at', `$gp', and `$sp' respectively.The 32 floating-point registers are referred to as `$fN'.File: as.info, Node: Alpha-Relocs, Prev: Alpha-Regs, Up: Alpha Syntax9.1.3.3 Relocations...................Some of these relocations are available for ECOFF, but mostly only forELF. They are modeled after the relocation format introduced inDigital Unix 4.0, but there are additions.The format is `!TAG' or `!TAG!NUMBER' where TAG is the name of therelocation. In some cases NUMBER is used to relate specificinstructions.The relocation is placed at the end of the instruction like so:ldah $0,a($29) !gprelhighlda $0,a($0) !gprellowldq $1,b($29) !literal!100ldl $2,0($1) !lituse_base!100`!literal'`!literal!N'Used with an `ldq' instruction to load the address of a symbolfrom the GOT.A sequence number N is optional, and if present is used to pair`lituse' relocations with this `literal' relocation. The `lituse'relocations are used by the linker to optimize the code based onthe final location of the symbol.Note that these optimizations are dependent on the data flow of theprogram. Therefore, if _any_ `lituse' is paired with a `literal'relocation, then _all_ uses of the register set by the `literal'instruction must also be marked with `lituse' relocations. Thisis because the original `literal' instruction may be deleted ortransformed into another instruction.Also note that there may be a one-to-many relationship between`literal' and `lituse', but not a many-to-one. That is, if thereare two code paths that load up the same address and feed thevalue to a single use, then the use may not use a `lituse'relocation.`!lituse_base!N'Used with any memory format instruction (e.g. `ldl') to indicatethat the literal is used for an address load. The offset field ofthe instruction must be zero. During relaxation, the code may bealtered to use a gp-relative load.`!lituse_jsr!N'Used with a register branch format instruction (e.g. `jsr') toindicate that the literal is used for a call. During relaxation,the code may be altered to use a direct branch (e.g. `bsr').`!lituse_jsrdirect!N'Similar to `lituse_jsr', but also that this call cannot be vectoredthrough a PLT entry. This is useful for functions with specialcalling conventions which do not allow the normal call-clobberedregisters to be clobbered.`!lituse_bytoff!N'Used with a byte mask instruction (e.g. `extbl') to indicate thatonly the low 3 bits of the address are relevant. Duringrelaxation, the code may be altered to use an immediate instead ofa register shift.`!lituse_addr!N'Used with any other instruction to indicate that the originaladdress is in fact used, and the original `ldq' instruction maynot be altered or deleted. This is useful in conjunction with`lituse_jsr' to test whether a weak symbol is defined.ldq $27,foo($29) !literal!1beq $27,is_undef !lituse_addr!1jsr $26,($27),foo !lituse_jsr!1`!lituse_tlsgd!N'Used with a register branch format instruction to indicate that theliteral is the call to `__tls_get_addr' used to compute theaddress of the thread-local storage variable whose descriptor wasloaded with `!tlsgd!N'.`!lituse_tlsldm!N'Used with a register branch format instruction to indicate that theliteral is the call to `__tls_get_addr' used to compute theaddress of the base of the thread-local storage block for thecurrent module. The descriptor for the module must have beenloaded with `!tlsldm!N'.`!gpdisp!N'Used with `ldah' and `lda' to load the GP from the currentaddress, a-la the `ldgp' macro. The source register for the`ldah' instruction must contain the address of the `ldah'instruction. There must be exactly one `lda' instruction pairedwith the `ldah' instruction, though it may appear anywhere in theinstruction stream. The immediate operands must be zero.bsr $26,fooldah $29,0($26) !gpdisp!1lda $29,0($29) !gpdisp!1`!gprelhigh'Used with an `ldah' instruction to add the high 16 bits of a32-bit displacement from the GP.`!gprellow'Used with any memory format instruction to add the low 16 bits of a32-bit displacement from the GP.`!gprel'Used with any memory format instruction to add a 16-bitdisplacement from the GP.`!samegp'Used with any branch format instruction to skip the GP load at thetarget address. The referenced symbol must have the same GP as thesource object file, and it must be declared to either not use `$27'or perform a standard GP load in the first two instructions via the`.prologue' directive.`!tlsgd'`!tlsgd!N'Used with an `lda' instruction to load the address of a TLSdescriptor for a symbol in the GOT.The sequence number N is optional, and if present it used to pairthe descriptor load with both the `literal' loading the address ofthe `__tls_get_addr' function and the `lituse_tlsgd' marking thecall to that function.For proper relaxation, both the `tlsgd', `literal' and `lituse'relocations must be in the same extended basic block. That is,the relocation with the lowest address must be executed first atruntime.`!tlsldm'`!tlsldm!N'Used with an `lda' instruction to load the address of a TLSdescriptor for the current module in the GOT.Similar in other respects to `tlsgd'.`!gotdtprel'Used with an `ldq' instruction to load the offset of the TLSsymbol within its module's thread-local storage block. Also knownas the dynamic thread pointer offset or dtp-relative offset.`!dtprelhi'`!dtprello'`!dtprel'Like `gprel' relocations except they compute dtp-relative offsets.`!gottprel'Used with an `ldq' instruction to load the offset of the TLSsymbol from the thread pointer. Also known as the tp-relativeoffset.`!tprelhi'`!tprello'`!tprel'Like `gprel' relocations except they compute tp-relative offsets.File: as.info, Node: Alpha Floating Point, Next: Alpha Directives, Prev: Alpha Syntax, Up: Alpha-Dependent9.1.4 Floating Point--------------------The Alpha family uses both IEEE and VAX floating-point numbers.File: as.info, Node: Alpha Directives, Next: Alpha Opcodes, Prev: Alpha Floating Point, Up: Alpha-Dependent9.1.5 Alpha Assembler Directives--------------------------------`as' for the Alpha supports many additional directives forcompatibility with the native assembler. This section describes themonly briefly.These are the additional directives in `as' for the Alpha:`.arch CPU'Specifies the target processor. This is equivalent to the `-mCPU'command-line option. *Note Options: Alpha Options, for a list ofvalues for CPU.`.ent FUNCTION[, N]'Mark the beginning of FUNCTION. An optional number may follow forcompatibility with the OSF/1 assembler, but is ignored. Whengenerating `.mdebug' information, this will create a proceduredescriptor for the function. In ELF, it will mark the symbol as afunction a-la the generic `.type' directive.`.end FUNCTION'Mark the end of FUNCTION. In ELF, it will set the size of thesymbol a-la the generic `.size' directive.`.mask MASK, OFFSET'Indicate which of the integer registers are saved in the currentfunction's stack frame. MASK is interpreted a bit mask in whichbit N set indicates that register N is saved. The registers aresaved in a block located OFFSET bytes from the "canonical frameaddress" (CFA) which is the value of the stack pointer on entry tothe function. The registers are saved sequentially, except thatthe return address register (normally `$26') is saved first.This and the other directives that describe the stack frame arecurrently only used when generating `.mdebug' information. Theymay in the future be used to generate DWARF2 `.debug_frame' unwindinformation for hand written assembly.`.fmask MASK, OFFSET'Indicate which of the floating-point registers are saved in thecurrent stack frame. The MASK and OFFSET parameters areinterpreted as with `.mask'.`.frame FRAMEREG, FRAMEOFFSET, RETREG[, ARGOFFSET]'Describes the shape of the stack frame. The frame pointer in useis FRAMEREG; normally this is either `$fp' or `$sp'. The framepointer is FRAMEOFFSET bytes below the CFA. The return address isinitially located in RETREG until it is saved as indicated in`.mask'. For compatibility with OSF/1 an optional ARGOFFSETparameter is accepted and ignored. It is believed to indicate theoffset from the CFA to the saved argument registers.`.prologue N'Indicate that the stack frame is set up and all registers have beenspilled. The argument N indicates whether and how the functionuses the incoming "procedure vector" (the address of the calledfunction) in `$27'. 0 indicates that `$27' is not used; 1indicates that the first two instructions of the function use `$27'to perform a load of the GP register; 2 indicates that `$27' isused in some non-standard way and so the linker cannot elide theload of the procedure vector during relaxation.`.usepv FUNCTION, WHICH'Used to indicate the use of the `$27' register, similar to`.prologue', but without the other semantics of needing to beinside an open `.ent'/`.end' block.The WHICH argument should be either `no', indicating that `$27' isnot used, or `std', indicating that the first two instructions ofthe function perform a GP load.One might use this directive instead of `.prologue' if you arealso using dwarf2 CFI directives.`.gprel32 EXPRESSION'Computes the difference between the address in EXPRESSION and theGP for the current object file, and stores it in 4 bytes. Inaddition to being smaller than a full 8 byte address, this alsodoes not require a dynamic relocation when used in a sharedlibrary.`.t_floating EXPRESSION'Stores EXPRESSION as an IEEE double precision value.`.s_floating EXPRESSION'Stores EXPRESSION as an IEEE single precision value.`.f_floating EXPRESSION'Stores EXPRESSION as a VAX F format value.`.g_floating EXPRESSION'Stores EXPRESSION as a VAX G format value.`.d_floating EXPRESSION'Stores EXPRESSION as a VAX D format value.`.set FEATURE'Enables or disables various assembler features. Using the positivename of the feature enables while using `noFEATURE' disables.`at'Indicates that macro expansions may clobber the "assemblertemporary" (`$at' or `$28') register. Some macros may not beexpanded without this and will generate an error message if`noat' is in effect. When `at' is in effect, a warning willbe generated if `$at' is used by the programmer.`macro'Enables the expansion of macro instructions. Note thatvariants of real instructions, such as `br label' vs `br$31,label' are considered alternate forms and not macros.`move'`reorder'`volatile'These control whether and how the assembler may re-orderinstructions. Accepted for compatibility with the OSF/1assembler, but `as' does not do instruction scheduling, sothese features are ignored.The following directives are recognized for compatibility with theOSF/1 assembler but are ignored..proc .aproc.reguse .livereg.option .aent.ugen .eflag.alias .noaliasFile: as.info, Node: Alpha Opcodes, Prev: Alpha Directives, Up: Alpha-Dependent9.1.6 Opcodes-------------For detailed information on the Alpha machine instruction set, see theAlpha Architecture Handbook(ftp://ftp.digital.com/pub/Digital/info/semiconductor/literature/alphaahb.pdf).File: as.info, Node: ARC-Dependent, Next: ARM-Dependent, Prev: Alpha-Dependent, Up: Machine Dependencies9.2 ARC Dependent Features==========================* Menu:* ARC Options:: Options* ARC Syntax:: Syntax* ARC Floating Point:: Floating Point* ARC Directives:: ARC Machine Directives* ARC Opcodes:: OpcodesFile: as.info, Node: ARC Options, Next: ARC Syntax, Up: ARC-Dependent9.2.1 Options-------------`-marc[5|6|7|8]'This option selects the core processor variant. Using `-marc' isthe same as `-marc6', which is also the default.`arc5'Base instruction set.`arc6'Jump-and-link (jl) instruction. No requirement of aninstruction between setting flags and conditional jump. Forexample:mov.f r0,r1beq foo`arc7'Break (brk) and sleep (sleep) instructions.`arc8'Software interrupt (swi) instruction.Note: the `.option' directive can to be used to select a corevariant from within assembly code.`-EB'This option specifies that the output generated by the assemblershould be marked as being encoded for a big-endian processor.`-EL'This option specifies that the output generated by the assemblershould be marked as being encoded for a little-endian processor -this is the default.File: as.info, Node: ARC Syntax, Next: ARC Floating Point, Prev: ARC Options, Up: ARC-Dependent9.2.2 Syntax------------* Menu:* ARC-Chars:: Special Characters* ARC-Regs:: Register NamesFile: as.info, Node: ARC-Chars, Next: ARC-Regs, Up: ARC Syntax9.2.2.1 Special Characters..........................*TODO*File: as.info, Node: ARC-Regs, Prev: ARC-Chars, Up: ARC Syntax9.2.2.2 Register Names......................*TODO*File: as.info, Node: ARC Floating Point, Next: ARC Directives, Prev: ARC Syntax, Up: ARC-Dependent9.2.3 Floating Point--------------------The ARC core does not currently have hardware floating point support.Software floating point support is provided by `GCC' and uses IEEEfloating-point numbers.File: as.info, Node: ARC Directives, Next: ARC Opcodes, Prev: ARC Floating Point, Up: ARC-Dependent9.2.4 ARC Machine Directives----------------------------The ARC version of `as' supports the following additional machinedirectives:`.2byte EXPRESSIONS'*TODO*`.3byte EXPRESSIONS'*TODO*`.4byte EXPRESSIONS'*TODO*`.extAuxRegister NAME,ADDRESS,MODE'The ARCtangent A4 has extensible auxiliary register space. Theauxiliary registers can be defined in the assembler source code byusing this directive. The first parameter is the NAME of the newauxiallry register. The second parameter is the ADDRESS of theregister in the auxiliary register memory map for the variant ofthe ARC. The third parameter specifies the MODE in which theregister can be operated is and it can be one of:`r (readonly)'`w (write only)'`r|w (read or write)'For example:.extAuxRegister mulhi,0x12,wThis specifies an extension auxiliary register called _mulhi_which is at address 0x12 in the memory space and which is onlywritable.`.extCondCode SUFFIX,VALUE'The condition codes on the ARCtangent A4 are extensible and can bespecified by means of this assembler directive. They are specifiedby the suffix and the value for the condition code. They can beused to specify extra condition codes with any values. Forexample:.extCondCode is_busy,0x14add.is_busy r1,r2,r3bis_busy _main`.extCoreRegister NAME,REGNUM,MODE,SHORTCUT'Specifies an extension core register NAME for the application.This allows a register NAME with a valid REGNUM between 0 and 60,with the following as valid values for MODE`_r_ (readonly)'`_w_ (write only)'`_r|w_ (read or write)'The other parameter gives a description of the register having aSHORTCUT in the pipeline. The valid values are:`can_shortcut'`cannot_shortcut'For example:.extCoreRegister mlo,57,r,can_shortcutThis defines an extension core register mlo with the value 57 whichcan shortcut the pipeline.`.extInstruction NAME,OPCODE,SUBOPCODE,SUFFIXCLASS,SYNTAXCLASS'The ARCtangent A4 allows the user to specify extensioninstructions. The extension instructions are not macros. Theassembler creates encodings for use of these instructionsaccording to the specification by the user. The parameters are:*NAMEName of the extension instruction*OPCODEOpcode to be used. (Bits 27:31 in the encoding). Valid values0x10-0x1f or 0x03*SUBOPCODESubopcode to be used. Valid values are from 0x09-0x3f.However the correct value also depends on SYNTAXCLASS*SUFFIXCLASSDetermines the kinds of suffixes to be allowed. Valid valuesare `SUFFIX_NONE', `SUFFIX_COND', `SUFFIX_FLAG' whichindicates the absence or presence of conditional suffixes andflag setting by the extension instruction. It is alsopossible to specify that an instruction sets the flags and isconditional by using `SUFFIX_CODE' | `SUFFIX_FLAG'.*SYNTAXCLASSDetermines the syntax class for the instruction. It can havethe following values:``SYNTAX_2OP':'2 Operand Instruction``SYNTAX_3OP':'3 Operand InstructionIn addition there could be modifiers for the syntax class asdescribed below:Syntax Class Modifiers are:- `OP1_MUST_BE_IMM': Modifies syntax class SYNTAX_3OP,specifying that the first operand of a three-operandinstruction must be an immediate (i.e., the result isdiscarded). OP1_MUST_BE_IMM is used by bitwise ORing itwith SYNTAX_3OP as given in the example below. Thiscould usually be used to set the flags using specificinstructions and not retain results.- `OP1_IMM_IMPLIED': Modifies syntax class SYNTAX_20P, itspecifies that there is an implied immediate destinationoperand which does not appear in the syntax. Forexample, if the source code contains an instruction like:inst r1,r2it really means that the first argument is an impliedimmediate (that is, the result is discarded). This isthe same as though the source code were: inst 0,r1,r2.You use OP1_IMM_IMPLIED by bitwise ORing it withSYNTAX_20P.For example, defining 64-bit multiplier with immediate operands:.extInstruction mp64,0x14,0x0,SUFFIX_COND | SUFFIX_FLAG ,SYNTAX_3OP|OP1_MUST_BE_IMMThe above specifies an extension instruction called mp64 which has3 operands, sets the flags, can be used with a condition code, forwhich the first operand is an immediate. (Equivalent todiscarding the result of the operation)..extInstruction mul64,0x14,0x00,SUFFIX_COND, SYNTAX_2OP|OP1_IMM_IMPLIEDThis describes a 2 operand instruction with an implicit firstimmediate operand. The result of this operation would bediscarded.`.half EXPRESSIONS'*TODO*`.long EXPRESSIONS'*TODO*`.option ARC|ARC5|ARC6|ARC7|ARC8'The `.option' directive must be followed by the desired coreversion. Again `arc' is an alias for `arc6'.Note: the `.option' directive overrides the command line option`-marc'; a warning is emitted when the version is not consistentbetween the two - even for the implicit default core version(arc6).`.short EXPRESSIONS'*TODO*`.word EXPRESSIONS'*TODO*File: as.info, Node: ARC Opcodes, Prev: ARC Directives, Up: ARC-Dependent9.2.5 Opcodes-------------For information on the ARC instruction set, see `ARC ProgrammersReference Manual', ARC International (www.arc.com)File: as.info, Node: ARM-Dependent, Next: AVR-Dependent, Prev: ARC-Dependent, Up: Machine Dependencies9.3 ARM Dependent Features==========================* Menu:* ARM Options:: Options* ARM Syntax:: Syntax* ARM Floating Point:: Floating Point* ARM Directives:: ARM Machine Directives* ARM Opcodes:: Opcodes* ARM Mapping Symbols:: Mapping Symbols* ARM Unwinding Tutorial:: UnwindingFile: as.info, Node: ARM Options, Next: ARM Syntax, Up: ARM-Dependent9.3.1 Options-------------`-mcpu=PROCESSOR[+EXTENSION...]'This option specifies the target processor. The assembler willissue an error message if an attempt is made to assemble aninstruction which will not execute on the target processor. Thefollowing processor names are recognized: `arm1', `arm2', `arm250',`arm3', `arm6', `arm60', `arm600', `arm610', `arm620', `arm7',`arm7m', `arm7d', `arm7dm', `arm7di', `arm7dmi', `arm70', `arm700',`arm700i', `arm710', `arm710t', `arm720', `arm720t', `arm740t',`arm710c', `arm7100', `arm7500', `arm7500fe', `arm7t', `arm7tdmi',`arm7tdmi-s', `arm8', `arm810', `strongarm', `strongarm1',`strongarm110', `strongarm1100', `strongarm1110', `arm9', `arm920',`arm920t', `arm922t', `arm940t', `arm9tdmi', `fa526' (FaradayFA526 processor), `fa626' (Faraday FA626 processor), `arm9e',`arm926e', `arm926ej-s', `arm946e-r0', `arm946e', `arm946e-s',`arm966e-r0', `arm966e', `arm966e-s', `arm968e-s', `arm10t',`arm10tdmi', `arm10e', `arm1020', `arm1020t', `arm1020e',`arm1022e', `arm1026ej-s', `fa626te' (Faraday FA626TE processor),`fa726te' (Faraday FA726TE processor), `arm1136j-s', `arm1136jf-s',`arm1156t2-s', `arm1156t2f-s', `arm1176jz-s', `arm1176jzf-s',`mpcore', `mpcorenovfp', `cortex-a8', `cortex-a9', `cortex-r4',`cortex-m3', `ep9312' (ARM920 with Cirrus Maverick coprocessor),`i80200' (Intel XScale processor) `iwmmxt' (Intel(r) XScaleprocessor with Wireless MMX(tm) technology coprocessor) and`xscale'. The special name `all' may be used to allow theassembler to accept instructions valid for any ARM processor.In addition to the basic instruction set, the assembler can betold to accept various extension mnemonics that extend theprocessor using the co-processor instruction space. For example,`-mcpu=arm920+maverick' is equivalent to specifying`-mcpu=ep9312'. The following extensions are currently supported:`+maverick' `+iwmmxt' and `+xscale'.`-march=ARCHITECTURE[+EXTENSION...]'This option specifies the target architecture. The assembler willissue an error message if an attempt is made to assemble aninstruction which will not execute on the target architecture.The following architecture names are recognized: `armv1', `armv2',`armv2a', `armv2s', `armv3', `armv3m', `armv4', `armv4xm',`armv4t', `armv4txm', `armv5', `armv5t', `armv5txm', `armv5te',`armv5texp', `armv6', `armv6j', `armv6k', `armv6z', `armv6zk',`armv7', `armv7-a', `armv7-r', `armv7-m', `iwmmxt' and `xscale'.If both `-mcpu' and `-march' are specified, the assembler will usethe setting for `-mcpu'.The architecture option can be extended with the same instructionset extension options as the `-mcpu' option.`-mfpu=FLOATING-POINT-FORMAT'This option specifies the floating point format to assemble for.The assembler will issue an error message if an attempt is made toassemble an instruction which will not execute on the targetfloating point unit. The following format options are recognized:`softfpa', `fpe', `fpe2', `fpe3', `fpa', `fpa10', `fpa11',`arm7500fe', `softvfp', `softvfp+vfp', `vfp', `vfp10', `vfp10-r0',`vfp9', `vfpxd', `vfpv2' `vfpv3' `vfpv3-d16' `arm1020t',`arm1020e', `arm1136jf-s', `maverick' and `neon'.In addition to determining which instructions are assembled, thisoption also affects the way in which the `.double' assemblerdirective behaves when assembling little-endian code.The default is dependent on the processor selected. ForArchitecture 5 or later, the default is to assembler for VFPinstructions; for earlier architectures the default is to assemblefor FPA instructions.`-mthumb'This option specifies that the assembler should start assemblingThumb instructions; that is, it should behave as though the filestarts with a `.code 16' directive.`-mthumb-interwork'This option specifies that the output generated by the assemblershould be marked as supporting interworking.`-mapcs `[26|32]''This option specifies that the output generated by the assemblershould be marked as supporting the indicated version of the ArmProcedure. Calling Standard.`-matpcs'This option specifies that the output generated by the assemblershould be marked as supporting the Arm/Thumb Procedure CallingStandard. If enabled this option will cause the assembler tocreate an empty debugging section in the object file called.arm.atpcs. Debuggers can use this to determine the ABI beingused by.`-mapcs-float'This indicates the floating point variant of the APCS should beused. In this variant floating point arguments are passed in FPregisters rather than integer registers.`-mapcs-reentrant'This indicates that the reentrant variant of the APCS should beused. This variant supports position independent code.`-mfloat-abi=ABI'This option specifies that the output generated by the assemblershould be marked as using specified floating point ABI. Thefollowing values are recognized: `soft', `softfp' and `hard'.`-meabi=VER'This option specifies which EABI version the produced object filesshould conform to. The following values are recognized: `gnu', `4'and `5'.`-EB'This option specifies that the output generated by the assemblershould be marked as being encoded for a big-endian processor.`-EL'This option specifies that the output generated by the assemblershould be marked as being encoded for a little-endian processor.`-k'This option specifies that the output of the assembler should bemarked as position-independent code (PIC).`--fix-v4bx'Allow `BX' instructions in ARMv4 code. This is intended for usewith the linker option of the same name.File: as.info, Node: ARM Syntax, Next: ARM Floating Point, Prev: ARM Options, Up: ARM-Dependent9.3.2 Syntax------------* Menu:* ARM-Chars:: Special Characters* ARM-Regs:: Register Names* ARM-Relocations:: RelocationsFile: as.info, Node: ARM-Chars, Next: ARM-Regs, Up: ARM Syntax9.3.2.1 Special Characters..........................The presence of a `@' on a line indicates the start of a comment thatextends to the end of the current line. If a `#' appears as the firstcharacter of a line, the whole line is treated as a comment.The `;' character can be used instead of a newline to separatestatements.Either `#' or `$' can be used to indicate immediate operands.*TODO* Explain about /data modifier on symbols.File: as.info, Node: ARM-Regs, Next: ARM-Relocations, Prev: ARM-Chars, Up: ARM Syntax9.3.2.2 Register Names......................*TODO* Explain about ARM register naming, and the predefined names.File: as.info, Node: ARM Floating Point, Next: ARM Directives, Prev: ARM Syntax, Up: ARM-Dependent9.3.3 Floating Point--------------------The ARM family uses IEEE floating-point numbers.File: as.info, Node: ARM-Relocations, Prev: ARM-Regs, Up: ARM Syntax9.3.3.1 ARM relocation generation.................................Specific data relocations can be generated by putting the relocationname in parentheses after the symbol name. For example:.word foo(TARGET1)This will generate an `R_ARM_TARGET1' relocation against the symbolFOO. The following relocations are supported: `GOT', `GOTOFF',`TARGET1', `TARGET2', `SBREL', `TLSGD', `TLSLDM', `TLSLDO', `GOTTPOFF'and `TPOFF'.For compatibility with older toolchains the assembler also accepts`(PLT)' after branch targets. This will generate the deprecated`R_ARM_PLT32' relocation.Relocations for `MOVW' and `MOVT' instructions can be generated byprefixing the value with `#:lower16:' and `#:upper16' respectively.For example to load the 32-bit address of foo into r0:MOVW r0, #:lower16:fooMOVT r0, #:upper16:fooFile: as.info, Node: ARM Directives, Next: ARM Opcodes, Prev: ARM Floating Point, Up: ARM-Dependent9.3.4 ARM Machine Directives----------------------------`.align EXPRESSION [, EXPRESSION]'This is the generic .ALIGN directive. For the ARM however if thefirst argument is zero (ie no alignment is needed) the assemblerwill behave as if the argument had been 2 (ie pad to the next fourbyte boundary). This is for compatibility with ARM's ownassembler.`NAME .req REGISTER NAME'This creates an alias for REGISTER NAME called NAME. For example:foo .req r0`.unreq ALIAS-NAME'This undefines a register alias which was previously defined usingthe `req', `dn' or `qn' directives. For example:foo .req r0.unreq fooAn error occurs if the name is undefined. Note - this pseudo opcan be used to delete builtin in register name aliases (eg 'r0').This should only be done if it is really necessary.`NAME .dn REGISTER NAME [.TYPE] [[INDEX]]'`NAME .qn REGISTER NAME [.TYPE] [[INDEX]]'The `dn' and `qn' directives are used to create typed and/orindexed register aliases for use in Advanced SIMD Extension (Neon)instructions. The former should be used to create aliases ofdouble-precision registers, and the latter to create aliases ofquad-precision registers.If these directives are used to create typed aliases, thosealiases can be used in Neon instructions instead of writing typesafter the mnemonic or after each operand. For example:x .dn d2.f32y .dn d3.f32z .dn d4.f32[1]vmul x,y,zThis is equivalent to writing the following:vmul.f32 d2,d3,d4[1]Aliases created using `dn' or `qn' can be destroyed using `unreq'.`.code `[16|32]''This directive selects the instruction set being generated. Thevalue 16 selects Thumb, with the value 32 selecting ARM.`.thumb'This performs the same action as .CODE 16.`.arm'This performs the same action as .CODE 32.`.force_thumb'This directive forces the selection of Thumb instructions, even ifthe target processor does not support those instructions`.thumb_func'This directive specifies that the following symbol is the name of aThumb encoded function. This information is necessary in order toallow the assembler and linker to generate correct code forinterworking between Arm and Thumb instructions and should be usedeven if interworking is not going to be performed. The presenceof this directive also implies `.thumb'This directive is not neccessary when generating EABI objects. Onthese targets the encoding is implicit when generating Thumb code.`.thumb_set'This performs the equivalent of a `.set' directive in that itcreates a symbol which is an alias for another symbol (possiblynot yet defined). This directive also has the added property inthat it marks the aliased symbol as being a thumb function entrypoint, in the same way that the `.thumb_func' directive does.`.ltorg'This directive causes the current contents of the literal pool tobe dumped into the current section (which is assumed to be the.text section) at the current location (aligned to a wordboundary). `GAS' maintains a separate literal pool for eachsection and each sub-section. The `.ltorg' directive will onlyaffect the literal pool of the current section and sub-section.At the end of assembly all remaining, un-empty literal pools willautomatically be dumped.Note - older versions of `GAS' would dump the current literal poolany time a section change occurred. This is no longer done, sinceit prevents accurate control of the placement of literal pools.`.pool'This is a synonym for .ltorg.`.fnstart'Marks the start of a function with an unwind table entry.`.fnend'Marks the end of a function with an unwind table entry. Theunwind index table entry is created when this directive isprocessed.If no personality routine has been specified then standardpersonality routine 0 or 1 will be used, depending on the numberof unwind opcodes required.`.cantunwind'Prevents unwinding through the current function. No personalityroutine or exception table data is required or permitted.`.personality NAME'Sets the personality routine for the current function to NAME.`.personalityindex INDEX'Sets the personality routine for the current function to the EABIstandard routine number INDEX`.handlerdata'Marks the end of the current function, and the start of theexception table entry for that function. Anything between thisdirective and the `.fnend' directive will be added to theexception table entry.Must be preceded by a `.personality' or `.personalityindex'directive.`.save REGLIST'Generate unwinder annotations to restore the registers in REGLIST.The format of REGLIST is the same as the correspondingstore-multiple instruction._core registers_.save {r4, r5, r6, lr}stmfd sp!, {r4, r5, r6, lr}_FPA registers_.save f4, 2sfmfd f4, 2, [sp]!_VFP registers_.save {d8, d9, d10}fstmdx sp!, {d8, d9, d10}_iWMMXt registers_.save {wr10, wr11}wstrd wr11, [sp, #-8]!wstrd wr10, [sp, #-8]!or.save wr11wstrd wr11, [sp, #-8]!.save wr10wstrd wr10, [sp, #-8]!`.vsave VFP-REGLIST'Generate unwinder annotations to restore the VFP registers inVFP-REGLIST using FLDMD. Also works for VFPv3 registers that areto be restored using VLDM. The format of VFP-REGLIST is the sameas the corresponding store-multiple instruction._VFP registers_.vsave {d8, d9, d10}fstmdd sp!, {d8, d9, d10}_VFPv3 registers_.vsave {d15, d16, d17}vstm sp!, {d15, d16, d17}Since FLDMX and FSTMX are now deprecated, this directive should beused in favour of `.save' for saving VFP registers for ARMv6 andabove.`.pad #COUNT'Generate unwinder annotations for a stack adjustment of COUNTbytes. A positive value indicates the function prologue allocatedstack space by decrementing the stack pointer.`.movsp REG [, #OFFSET]'Tell the unwinder that REG contains an offset from the currentstack pointer. If OFFSET is not specified then it is assumed to bezero.`.setfp FPREG, SPREG [, #OFFSET]'Make all unwinder annotations relaive to a frame pointer. Withoutthis the unwinder will use offsets from the stack pointer.The syntax of this directive is the same as the `sub' or `mov'instruction used to set the frame pointer. SPREG must be either`sp' or mentioned in a previous `.movsp' directive..movsp ipmov ip, sp....setfp fp, ip, #4sub fp, ip, #4`.raw OFFSET, BYTE1, ...'Insert one of more arbitary unwind opcode bytes, which are knownto adjust the stack pointer by OFFSET bytes.For example `.unwind_raw 4, 0xb1, 0x01' is equivalent to `.save{r0}'`.cpu NAME'Select the target processor. Valid values for NAME are the same asfor the `-mcpu' commandline option.`.arch NAME'Select the target architecture. Valid values for NAME are thesame as for the `-march' commandline option.`.object_arch NAME'Override the architecture recorded in the EABI object attributesection. Valid values for NAME are the same as for the `.arch'directive. Typically this is useful when code uses runtimedetection of CPU features.`.fpu NAME'Select the floating point unit to assemble for. Valid values forNAME are the same as for the `-mfpu' commandline option.`.eabi_attribute TAG, VALUE'Set the EABI object attribute number TAG to VALUE. The value iseither a `number', `"string"', or `number, "string"' depending onthe tag.File: as.info, Node: ARM Opcodes, Next: ARM Mapping Symbols, Prev: ARM Directives, Up: ARM-Dependent9.3.5 Opcodes-------------`as' implements all the standard ARM opcodes. It also implementsseveral pseudo opcodes, including several synthetic load instructions.`NOP'nopThis pseudo op will always evaluate to a legal ARM instructionthat does nothing. Currently it will evaluate to MOV r0, r0.`LDR'ldr <register> , = <expression>If expression evaluates to a numeric constant then a MOV or MVNinstruction will be used in place of the LDR instruction, if theconstant can be generated by either of these instructions.Otherwise the constant will be placed into the nearest literalpool (if it not already there) and a PC relative LDR instructionwill be generated.`ADR'adr <register> <label>This instruction will load the address of LABEL into the indicatedregister. The instruction will evaluate to a PC relative ADD orSUB instruction depending upon where the label is located. If thelabel is out of range, or if it is not defined in the same file(and section) as the ADR instruction, then an error will begenerated. This instruction will not make use of the literal pool.`ADRL'adrl <register> <label>This instruction will load the address of LABEL into the indicatedregister. The instruction will evaluate to one or two PC relativeADD or SUB instructions depending upon where the label is located.If a second instruction is not needed a NOP instruction will begenerated in its place, so that this instruction is always 8 byteslong.If the label is out of range, or if it is not defined in the samefile (and section) as the ADRL instruction, then an error will begenerated. This instruction will not make use of the literal pool.For information on the ARM or Thumb instruction sets, see `ARMSoftware Development Toolkit Reference Manual', Advanced RISC MachinesLtd.File: as.info, Node: ARM Mapping Symbols, Next: ARM Unwinding Tutorial, Prev: ARM Opcodes, Up: ARM-Dependent9.3.6 Mapping Symbols---------------------The ARM ELF specification requires that special symbols be insertedinto object files to mark certain features:`$a'At the start of a region of code containing ARM instructions.`$t'At the start of a region of code containing THUMB instructions.`$d'At the start of a region of data.The assembler will automatically insert these symbols for you - thereis no need to code them yourself. Support for tagging symbols ($b, $f,$p and $m) which is also mentioned in the current ARM ELF specificationis not implemented. This is because they have been dropped from thenew EABI and so tools cannot rely upon their presence.File: as.info, Node: ARM Unwinding Tutorial, Prev: ARM Mapping Symbols, Up: ARM-Dependent9.3.7 Unwinding---------------The ABI for the ARM Architecture specifies a standard format forexception unwind information. This information is used when anexception is thrown to determine where control should be transferred.In particular, the unwind information is used to determine whichfunction called the function that threw the exception, and whichfunction called that one, and so forth. This information is also usedto restore the values of callee-saved registers in the functioncatching the exception.If you are writing functions in assembly code, and those functionscall other functions that throw exceptions, you must use assemblypseudo ops to ensure that appropriate exception unwind information isgenerated. Otherwise, if one of the functions called by your assemblycode throws an exception, the run-time library will be unable to unwindthe stack through your assembly code and your program will not behavecorrectly.To illustrate the use of these pseudo ops, we will examine the codethat G++ generates for the following C++ input:void callee (int *);intcaller (){int i;callee (&i);return i;}This example does not show how to throw or catch an exception fromassembly code. That is a much more complex operation and should alwaysbe done in a high-level language, such as C++, that directly supportsexceptions.The code generated by one particular version of G++ when compilingthe example above is:_Z6callerv:.fnstart.LFB2:@ Function supports interworking.@ args = 0, pretend = 0, frame = 8@ frame_needed = 1, uses_anonymous_args = 0stmfd sp!, {fp, lr}.save {fp, lr}.LCFI0:.setfp fp, sp, #4add fp, sp, #4.LCFI1:.pad #8sub sp, sp, #8.LCFI2:sub r3, fp, #8mov r0, r3bl _Z6calleePildr r3, [fp, #-8]mov r0, r3sub sp, fp, #4ldmfd sp!, {fp, lr}bx lr.LFE2:.fnendOf course, the sequence of instructions varies based on the optionsyou pass to GCC and on the version of GCC in use. The exactinstructions are not important since we are focusing on the pseudo opsthat are used to generate unwind information.An important assumption made by the unwinder is that the stack framedoes not change during the body of the function. In particular, sincewe assume that the assembly code does not itself throw an exception,the only point where an exception can be thrown is from a call, such asthe `bl' instruction above. At each call site, the same savedregisters (including `lr', which indicates the return address) must belocated in the same locations relative to the frame pointer.The `.fnstart' (*note .fnstart pseudo op: arm_fnstart.) pseudo opappears immediately before the first instruction of the function whilethe `.fnend' (*note .fnend pseudo op: arm_fnend.) pseudo op appearsimmediately after the last instruction of the function. These pseudoops specify the range of the function.Only the order of the other pseudos ops (e.g., `.setfp' or `.pad')matters; their exact locations are irrelevant. In the example above,the compiler emits the pseudo ops with particular instructions. Thatmakes it easier to understand the code, but it is not required forcorrectness. It would work just as well to emit all of the pseudo opsother than `.fnend' in the same order, but immediately after `.fnstart'.The `.save' (*note .save pseudo op: arm_save.) pseudo op indicatesregisters that have been saved to the stack so that they can berestored before the function returns. The argument to the `.save'pseudo op is a list of registers to save. If a register is"callee-saved" (as specified by the ABI) and is modified by thefunction you are writing, then your code must save the value before itis modified and restore the original value before the function returns.If an exception is thrown, the run-time library restores the values ofthese registers from their locations on the stack before returningcontrol to the exception handler. (Of course, if an exception is notthrown, the function that contains the `.save' pseudo op restores theseregisters in the function epilogue, as is done with the `ldmfd'instruction above.)You do not have to save callee-saved registers at the very beginningof the function and you do not need to use the `.save' pseudo opimmediately following the point at which the registers are saved.However, if you modify a callee-saved register, you must save it on thestack before modifying it and before calling any functions which mightthrow an exception. And, you must use the `.save' pseudo op toindicate that you have done so.The `.pad' (*note .pad: arm_pad.) pseudo op indicates a modificationof the stack pointer that does not save any registers. The argument isthe number of bytes (in decimal) that are subtracted from the stackpointer. (On ARM CPUs, the stack grows downwards, so subtracting fromthe stack pointer increases the size of the stack.)The `.setfp' (*note .setfp pseudo op: arm_setfp.) pseudo opindicates the register that contains the frame pointer. The firstargument is the register that is set, which is typically `fp'. Thesecond argument indicates the register from which the frame pointertakes its value. The third argument, if present, is the value (indecimal) added to the register specified by the second argument tocompute the value of the frame pointer. You should not modify theframe pointer in the body of the function.If you do not use a frame pointer, then you should not use the`.setfp' pseudo op. If you do not use a frame pointer, then you shouldavoid modifying the stack pointer outside of the function prologue.Otherwise, the run-time library will be unable to find saved registerswhen it is unwinding the stack.The pseudo ops described above are sufficient for writing assemblycode that calls functions which may throw exceptions. If you need toknow more about the object-file format used to represent unwindinformation, you may consult the `Exception Handling ABI for the ARMArchitecture' available from `http://infocenter.arm.com'.File: as.info, Node: AVR-Dependent, Next: BFIN-Dependent, Prev: ARM-Dependent, Up: Machine Dependencies9.4 AVR Dependent Features==========================* Menu:* AVR Options:: Options* AVR Syntax:: Syntax* AVR Opcodes:: OpcodesFile: as.info, Node: AVR Options, Next: AVR Syntax, Up: AVR-Dependent9.4.1 Options-------------`-mmcu=MCU'Specify ATMEL AVR instruction set or MCU type.Instruction set avr1 is for the minimal AVR core, not supported bythe C compiler, only for assembler programs (MCU types: at90s1200,attiny11, attiny12, attiny15, attiny28).Instruction set avr2 (default) is for the classic AVR core with upto 8K program memory space (MCU types: at90s2313, at90s2323,at90s2333, at90s2343, attiny22, attiny26, at90s4414, at90s4433,at90s4434, at90s8515, at90c8534, at90s8535).Instruction set avr25 is for the classic AVR core with up to 8Kprogram memory space plus the MOVW instruction (MCU types:attiny13, attiny13a, attiny2313, attiny24, attiny44, attiny84,attiny25, attiny45, attiny85, attiny261, attiny461, attiny861,attiny43u, attiny48, attiny88, at86rf401).Instruction set avr3 is for the classic AVR core with up to 128Kprogram memory space (MCU types: at43usb355, at76c711).Instruction set avr31 is for the classic AVR core with exactly128K program memory space (MCU types: atmega103, at43usb320).Instruction set avr35 is for classic AVR core plus MOVW, CALL, andJMP instructions (MCU types: attiny167, at90usb82, at90usb162).Instruction set avr4 is for the enhanced AVR core with up to 8Kprogram memory space (MCU types: atmega48, atmega48p,atmega8,atmega88, atmega88p, atmega8515, atmega8535, atmega8hva, at90pwm1,at90pwm2, at90pwm2b, at90pwm3, at90pwm3b).Instruction set avr5 is for the enhanced AVR core with up to 128Kprogram memory space (MCU types: atmega16, atmega161, atmega162,atmega163, atmega164p, atmega165, atmega165p, atmega168,atmega168p, atmega169, atmega169p, atmega32, atmega323,atmega324p, atmega325, atmega325p, atmega3250, atmega3250p,atmega328p, atmega329, atmega329p, atmega3290, atmega3290p,atmega406, atmega64, atmega640, atmega644, atmega644p, atmega645,atmega6450, atmega649, atmega6490, atmega16hva, at90can32,at90can64, at90pwm216, at90pwm316, atmega16u4, atmega32c1,atmega32m1, atmega32u4, at90usb646, at90usb647, at94k).Instruction set avr51 is for the enhanced AVR core with exactly128K program memory space (MCU types: atmega128, atmega1280,atmega1281, atmega1284p, at90can128, at90usb1286, at90usb1287).Instruction set avr6 is for the enhanced AVR core with a 3-byte PC(MCU types: atmega2560, atmega2561).`-mall-opcodes'Accept all AVR opcodes, even if not supported by `-mmcu'.`-mno-skip-bug'This option disable warnings for skipping two-word instructions.`-mno-wrap'This option reject `rjmp/rcall' instructions with 8K wrap-around.File: as.info, Node: AVR Syntax, Next: AVR Opcodes, Prev: AVR Options, Up: AVR-Dependent9.4.2 Syntax------------* Menu:* AVR-Chars:: Special Characters* AVR-Regs:: Register Names* AVR-Modifiers:: Relocatable Expression ModifiersFile: as.info, Node: AVR-Chars, Next: AVR-Regs, Up: AVR Syntax9.4.2.1 Special Characters..........................The presence of a `;' on a line indicates the start of a comment thatextends to the end of the current line. If a `#' appears as the firstcharacter of a line, the whole line is treated as a comment.The `$' character can be used instead of a newline to separatestatements.File: as.info, Node: AVR-Regs, Next: AVR-Modifiers, Prev: AVR-Chars, Up: AVR Syntax9.4.2.2 Register Names......................The AVR has 32 x 8-bit general purpose working registers `r0', `r1',... `r31'. Six of the 32 registers can be used as three 16-bitindirect address register pointers for Data Space addressing. One ofthe these address pointers can also be used as an address pointer forlook up tables in Flash program memory. These added function registersare the 16-bit `X', `Y' and `Z' - registers.X = r26:r27Y = r28:r29Z = r30:r31File: as.info, Node: AVR-Modifiers, Prev: AVR-Regs, Up: AVR Syntax9.4.2.3 Relocatable Expression Modifiers........................................The assembler supports several modifiers when using relocatableaddresses in AVR instruction operands. The general syntax is thefollowing:modifier(relocatable-expression)`lo8'This modifier allows you to use bits 0 through 7 of an addressexpression as 8 bit relocatable expression.`hi8'This modifier allows you to use bits 7 through 15 of an addressexpression as 8 bit relocatable expression. This is useful with,for example, the AVR `ldi' instruction and `lo8' modifier.For exampleldi r26, lo8(sym+10)ldi r27, hi8(sym+10)`hh8'This modifier allows you to use bits 16 through 23 of an addressexpression as 8 bit relocatable expression. Also, can be usefulfor loading 32 bit constants.`hlo8'Synonym of `hh8'.`hhi8'This modifier allows you to use bits 24 through 31 of anexpression as 8 bit expression. This is useful with, for example,the AVR `ldi' instruction and `lo8', `hi8', `hlo8', `hhi8',modifier.For exampleldi r26, lo8(285774925)ldi r27, hi8(285774925)ldi r28, hlo8(285774925)ldi r29, hhi8(285774925); r29,r28,r27,r26 = 285774925`pm_lo8'This modifier allows you to use bits 0 through 7 of an addressexpression as 8 bit relocatable expression. This modifier usefulfor addressing data or code from Flash/Program memory. The usingof `pm_lo8' similar to `lo8'.`pm_hi8'This modifier allows you to use bits 8 through 15 of an addressexpression as 8 bit relocatable expression. This modifier usefulfor addressing data or code from Flash/Program memory.`pm_hh8'This modifier allows you to use bits 15 through 23 of an addressexpression as 8 bit relocatable expression. This modifier usefulfor addressing data or code from Flash/Program memory.File: as.info, Node: AVR Opcodes, Prev: AVR Syntax, Up: AVR-Dependent9.4.3 Opcodes-------------For detailed information on the AVR machine instruction set, see`www.atmel.com/products/AVR'.`as' implements all the standard AVR opcodes. The following tablesummarizes the AVR opcodes, and their arguments.Legend:r any registerd `ldi' register (r16-r31)v `movw' even register (r0, r2, ..., r28, r30)a `fmul' register (r16-r23)w `adiw' register (r24,r26,r28,r30)e pointer registers (X,Y,Z)b base pointer register and displacement ([YZ]+disp)z Z pointer register (for [e]lpm Rd,Z[+])M immediate value from 0 to 255n immediate value from 0 to 255 ( n = ~M ). Relocation impossibles immediate value from 0 to 7P Port address value from 0 to 63. (in, out)p Port address value from 0 to 31. (cbi, sbi, sbic, sbis)K immediate value from 0 to 63 (used in `adiw', `sbiw')i immediate valuel signed pc relative offset from -64 to 63L signed pc relative offset from -2048 to 2047h absolute code address (call, jmp)S immediate value from 0 to 7 (S = s << 4)? use this opcode entry if no parameters, else use next opcode entry1001010010001000 clc1001010011011000 clh1001010011111000 cli1001010010101000 cln1001010011001000 cls1001010011101000 clt1001010010111000 clv1001010010011000 clz1001010000001000 sec1001010001011000 seh1001010001111000 sei1001010000101000 sen1001010001001000 ses1001010001101000 set1001010000111000 sev1001010000011000 sez100101001SSS1000 bclr S100101000SSS1000 bset S1001010100001001 icall1001010000001001 ijmp1001010111001000 lpm ?1001000ddddd010+ lpm r,z1001010111011000 elpm ?1001000ddddd011+ elpm r,z0000000000000000 nop1001010100001000 ret1001010100011000 reti1001010110001000 sleep1001010110011000 break1001010110101000 wdr1001010111101000 spm000111rdddddrrrr adc r,r000011rdddddrrrr add r,r001000rdddddrrrr and r,r000101rdddddrrrr cp r,r000001rdddddrrrr cpc r,r000100rdddddrrrr cpse r,r001001rdddddrrrr eor r,r001011rdddddrrrr mov r,r100111rdddddrrrr mul r,r001010rdddddrrrr or r,r000010rdddddrrrr sbc r,r000110rdddddrrrr sub r,r001001rdddddrrrr clr r000011rdddddrrrr lsl r000111rdddddrrrr rol r001000rdddddrrrr tst r0111KKKKddddKKKK andi d,M0111KKKKddddKKKK cbr d,n1110KKKKddddKKKK ldi d,M11101111dddd1111 ser d0110KKKKddddKKKK ori d,M0110KKKKddddKKKK sbr d,M0011KKKKddddKKKK cpi d,M0100KKKKddddKKKK sbci d,M0101KKKKddddKKKK subi d,M1111110rrrrr0sss sbrc r,s1111111rrrrr0sss sbrs r,s1111100ddddd0sss bld r,s1111101ddddd0sss bst r,s10110PPdddddPPPP in r,P10111PPrrrrrPPPP out P,r10010110KKddKKKK adiw w,K10010111KKddKKKK sbiw w,K10011000pppppsss cbi p,s10011010pppppsss sbi p,s10011001pppppsss sbic p,s10011011pppppsss sbis p,s111101lllllll000 brcc l111100lllllll000 brcs l111100lllllll001 breq l111101lllllll100 brge l111101lllllll101 brhc l111100lllllll101 brhs l111101lllllll111 brid l111100lllllll111 brie l111100lllllll000 brlo l111100lllllll100 brlt l111100lllllll010 brmi l111101lllllll001 brne l111101lllllll010 brpl l111101lllllll000 brsh l111101lllllll110 brtc l111100lllllll110 brts l111101lllllll011 brvc l111100lllllll011 brvs l111101lllllllsss brbc s,l111100lllllllsss brbs s,l1101LLLLLLLLLLLL rcall L1100LLLLLLLLLLLL rjmp L1001010hhhhh111h call h1001010hhhhh110h jmp h1001010rrrrr0101 asr r1001010rrrrr0000 com r1001010rrrrr1010 dec r1001010rrrrr0011 inc r1001010rrrrr0110 lsr r1001010rrrrr0001 neg r1001000rrrrr1111 pop r1001001rrrrr1111 push r1001010rrrrr0111 ror r1001010rrrrr0010 swap r00000001ddddrrrr movw v,v00000010ddddrrrr muls d,d000000110ddd0rrr mulsu a,a000000110ddd1rrr fmul a,a000000111ddd0rrr fmuls a,a000000111ddd1rrr fmulsu a,a1001001ddddd0000 sts i,r1001000ddddd0000 lds r,i10o0oo0dddddbooo ldd r,b100!000dddddee-+ ld r,e10o0oo1rrrrrbooo std b,r100!001rrrrree-+ st e,r1001010100011001 eicall1001010000011001 eijmpFile: as.info, Node: BFIN-Dependent, Next: CR16-Dependent, Prev: AVR-Dependent, Up: Machine Dependencies9.5 Blackfin Dependent Features===============================* Menu:* BFIN Syntax:: BFIN Syntax* BFIN Directives:: BFIN DirectivesFile: as.info, Node: BFIN Syntax, Next: BFIN Directives, Up: BFIN-Dependent9.5.1 Syntax------------`Special Characters'Assembler input is free format and may appear anywhere on the line.One instruction may extend across multiple lines or more than oneinstruction may appear on the same line. White space (space, tab,comments or newline) may appear anywhere between tokens. A tokenmust not have embedded spaces. Tokens include numbers, registernames, keywords, user identifiers, and also some multicharacterspecial symbols like "+=", "/*" or "||".`Instruction Delimiting'A semicolon must terminate every instruction. Sometimes a completeinstruction will consist of more than one operation. There are twocases where this occurs. The first is when two general operationsare combined. Normally a comma separates the different parts, asina0= r3.h * r2.l, a1 = r3.l * r2.h ;The second case occurs when a general instruction is combined withone or two memory references for joint issue. The latter portionsare set off by a "||" token.a0 = r3.h * r2.l || r1 = [p3++] || r4 = [i2++];`Register Names'The assembler treats register names and instruction keywords in acase insensitive manner. User identifiers are case sensitive.Thus, R3.l, R3.L, r3.l and r3.L are all equivalent input to theassembler.Register names are reserved and may not be used as programidentifiers.Some operations (such as "Move Register") require a register pair.Register pairs are always data registers and are denoted using acolon, eg., R3:2. The larger number must be written firsts. Notethat the hardware only supports odd-even pairs, eg., R7:6, R5:4,R3:2, and R1:0.Some instructions (such as -SP (Push Multiple)) require a group ofadjacent registers. Adjacent registers are denoted in the syntaxby the range enclosed in parentheses and separated by a colon,eg., (R7:3). Again, the larger number appears first.Portions of a particular register may be individually specified.This is written with a dot (".") following the register name andthen a letter denoting the desired portion. For 32-bit registers,".H" denotes the most significant ("High") portion. ".L" denotesthe least-significant portion. The subdivisions of the 40-bitregisters are described later.`Accumulators'The set of 40-bit registers A1 and A0 that normally contain datathat is being manipulated. Each accumulator can be accessed infour ways.`one 40-bit register'The register will be referred to as A1 or A0.`one 32-bit register'The registers are designated as A1.W or A0.W.`two 16-bit registers'The registers are designated as A1.H, A1.L, A0.H or A0.L.`one 8-bit register'The registers are designated as A1.X or A0.X for the bits thatextend beyond bit 31.`Data Registers'The set of 32-bit registers (R0, R1, R2, R3, R4, R5, R6 and R7)that normally contain data for manipulation. These areabbreviated as D-register or Dreg. Data registers can be accessedas 32-bit registers or as two independent 16-bit registers. Theleast significant 16 bits of each register is called the "low"half and is designated with ".L" following the register name. Themost significant 16 bits are called the "high" half and isdesignated with ".H" following the name.R7.L, r2.h, r4.L, R0.H`Pointer Registers'The set of 32-bit registers (P0, P1, P2, P3, P4, P5, SP and FP)that normally contain byte addresses of data structures. These areabbreviated as P-register or Preg.p2, p5, fp, sp`Stack Pointer SP'The stack pointer contains the 32-bit address of the last occupiedbyte location in the stack. The stack grows by decrementing thestack pointer.`Frame Pointer FP'The frame pointer contains the 32-bit address of the previous framepointer in the stack. It is located at the top of a frame.`Loop Top'LT0 and LT1. These registers contain the 32-bit address of thetop of a zero overhead loop.`Loop Count'LC0 and LC1. These registers contain the 32-bit counter of thezero overhead loop executions.`Loop Bottom'LB0 and LB1. These registers contain the 32-bit address of thebottom of a zero overhead loop.`Index Registers'The set of 32-bit registers (I0, I1, I2, I3) that normally containbyte addresses of data structures. Abbreviated I-register or Ireg.`Modify Registers'The set of 32-bit registers (M0, M1, M2, M3) that normally containoffset values that are added and subracted to one of the indexregisters. Abbreviated as Mreg.`Length Registers'The set of 32-bit registers (L0, L1, L2, L3) that normally containthe length in bytes of the circular buffer. Abbreviated as Lreg.Clear the Lreg to disable circular addressing for thecorresponding Ireg.`Base Registers'The set of 32-bit registers (B0, B1, B2, B3) that normally containthe base address in bytes of the circular buffer. Abbreviated asBreg.`Floating Point'The Blackfin family has no hardware floating point but the .floatdirective generates ieee floating point numbers for use withsoftware floating point libraries.`Blackfin Opcodes'For detailed information on the Blackfin machine instruction set,see the Blackfin(r) Processor Instruction Set Reference.File: as.info, Node: BFIN Directives, Prev: BFIN Syntax, Up: BFIN-Dependent9.5.2 Directives----------------The following directives are provided for compatibility with the VDSPassembler.`.byte2'Initializes a four byte data object.`.byte4'Initializes a two byte data object.`.db'TBD`.dd'TBD`.dw'TBD`.var'Define and initialize a 32 bit data object.File: as.info, Node: CR16-Dependent, Next: CRIS-Dependent, Prev: BFIN-Dependent, Up: Machine Dependencies9.6 CR16 Dependent Features===========================* Menu:* CR16 Operand Qualifiers:: CR16 Machine Operand QualifiersFile: as.info, Node: CR16 Operand Qualifiers, Up: CR16-Dependent9.6.1 CR16 Operand Qualifiers-----------------------------The National Semiconductor CR16 target of `as' has a few machinedependent operand qualifiers.Operand expression type qualifier is an optional field in theinstruction operand, to determines the type of the expression field ofan operand. The `@' is required. CR16 architecture uses one of thefollowing expression qualifiers:`s'- `Specifies expression operand type as small'`m'- `Specifies expression operand type as medium'`l'- `Specifies expression operand type as large'`c'- `Specifies the CR16 Assembler generates a relocation entry forthe operand, where pc has implied bit, the expression is adjustedaccordingly. The linker uses the relocation entry to update theoperand address at link time.'CR16 target operand qualifiers and its size (in bits):`Immediate Operand'- s --- 4 bits`'- m --- 16 bits, for movb and movw instructions.`'- m --- 20 bits, movd instructions.`'- l --- 32 bits`Absolute Operand'- s --- Illegal specifier for this operand.`'- m --- 20 bits, movd instructions.`Displacement Operand'- s --- 8 bits`'- m --- 16 bits`'- l --- 24 bitsFor example:1 `movw $_myfun@c,r1'This loads the address of _myfun, shifted right by 1, into r1.2 `movd $_myfun@c,(r2,r1)'This loads the address of _myfun, shifted right by 1, into register-pair r2-r1.3 `_myfun_ptr:'`.long _myfun@c'`loadd _myfun_ptr, (r1,r0)'`jal (r1,r0)'This .long directive, the address of _myfunc, shifted right by 1 at link time.File: as.info, Node: CRIS-Dependent, Next: D10V-Dependent, Prev: CR16-Dependent, Up: Machine Dependencies9.7 CRIS Dependent Features===========================* Menu:* CRIS-Opts:: Command-line Options* CRIS-Expand:: Instruction expansion* CRIS-Symbols:: Symbols* CRIS-Syntax:: SyntaxFile: as.info, Node: CRIS-Opts, Next: CRIS-Expand, Up: CRIS-Dependent9.7.1 Command-line Options--------------------------The CRIS version of `as' has these machine-dependent command-lineoptions.The format of the generated object files can be either ELF or a.out,specified by the command-line options `--emulation=crisaout' and`--emulation=criself'. The default is ELF (criself), unless `as' hasbeen configured specifically for a.out by using the configuration name`cris-axis-aout'.There are two different link-incompatible ELF object file variantsfor CRIS, for use in environments where symbols are expected to beprefixed by a leading `_' character and for environments without such asymbol prefix. The variant used for GNU/Linux port has no symbolprefix. Which variant to produce is specified by either of the options`--underscore' and `--no-underscore'. The default is `--underscore'.Since symbols in CRIS a.out objects are expected to have a `_' prefix,specifying `--no-underscore' when generating a.out objects is an error.Besides the object format difference, the effect of this option is toparse register names differently (*note crisnous::). The`--no-underscore' option makes a `$' register prefix mandatory.The option `--pic' must be passed to `as' in order to recognize thesymbol syntax used for ELF (SVR4 PIC) position-independent-code (*notecrispic::). This will also affect expansion of instructions. Theexpansion with `--pic' will use PC-relative rather than (slightlyfaster) absolute addresses in those expansions.The option `--march=ARCHITECTURE' specifies the recognizedinstruction set and recognized register names. It also controls thearchitecture type of the object file. Valid values for ARCHITECTUREare:`v0_v10'All instructions and register names for any architecture variantin the set v0...v10 are recognized. This is the default if thetarget is configured as cris-*.`v10'Only instructions and register names for CRIS v10 (as found inETRAX 100 LX) are recognized. This is the default if the targetis configured as crisv10-*.`v32'Only instructions and register names for CRIS v32 (code nameGuinness) are recognized. This is the default if the target isconfigured as crisv32-*. This value implies `--no-mul-bug-abort'.(A subsequent `--mul-bug-abort' will turn it back on.)`common_v10_v32'Only instructions with register names and addressing modes withopcodes common to the v10 and v32 are recognized.When `-N' is specified, `as' will emit a warning when a 16-bitbranch instruction is expanded into a 32-bit multiple-instructionconstruct (*note CRIS-Expand::).Some versions of the CRIS v10, for example in the Etrax 100 LX,contain a bug that causes destabilizing memory accesses when a multiplyinstruction is executed with certain values in the first operand justbefore a cache-miss. When the `--mul-bug-abort' command line option isactive (the default value), `as' will refuse to assemble a filecontaining a multiply instruction at a dangerous offset, one that couldbe the last on a cache-line, or is in a section with insufficientalignment. This placement checking does not catch any case where themultiply instruction is dangerously placed because it is located in adelay-slot. The `--mul-bug-abort' command line option turns off thechecking.File: as.info, Node: CRIS-Expand, Next: CRIS-Symbols, Prev: CRIS-Opts, Up: CRIS-Dependent9.7.2 Instruction expansion---------------------------`as' will silently choose an instruction that fits the operand size for`[register+constant]' operands. For example, the offset `127' in`move.d [r3+127],r4' fits in an instruction using a signed-byte offset.Similarly, `move.d [r2+32767],r1' will generate an instruction using a16-bit offset. For symbolic expressions and constants that do not fitin 16 bits including the sign bit, a 32-bit offset is generated.For branches, `as' will expand from a 16-bit branch instruction intoa sequence of instructions that can reach a full 32-bit address. Sincethis does not correspond to a single instruction, such expansions canoptionally be warned about. *Note CRIS-Opts::.If the operand is found to fit the range, a `lapc' mnemonic willtranslate to a `lapcq' instruction. Use `lapc.d' to force the 32-bit`lapc' instruction.Similarly, the `addo' mnemonic will translate to the shortestfitting instruction of `addoq', `addo.w' and `addo.d', when used with aoperand that is a constant known at assembly time.File: as.info, Node: CRIS-Symbols, Next: CRIS-Syntax, Prev: CRIS-Expand, Up: CRIS-Dependent9.7.3 Symbols-------------Some symbols are defined by the assembler. They're intended to be usedin conditional assembly, for example:.if ..asm.arch.cris.v32CODE FOR CRIS V32.elseif ..asm.arch.cris.common_v10_v32CODE COMMON TO CRIS V32 AND CRIS V10.elseif ..asm.arch.cris.v10 | ..asm.arch.cris.any_v0_v10CODE FOR V10.else.error "Code needs to be added here.".endifThese symbols are defined in the assembler, reflecting command-lineoptions, either when specified or the default. They are alwaysdefined, to 0 or 1.`..asm.arch.cris.any_v0_v10'This symbol is non-zero when `--march=v0_v10' is specified or thedefault.`..asm.arch.cris.common_v10_v32'Set according to the option `--march=common_v10_v32'.`..asm.arch.cris.v10'Reflects the option `--march=v10'.`..asm.arch.cris.v32'Corresponds to `--march=v10'.Speaking of symbols, when a symbol is used in code, it can have asuffix modifying its value for use in position-independent code. *NoteCRIS-Pic::.File: as.info, Node: CRIS-Syntax, Prev: CRIS-Symbols, Up: CRIS-Dependent9.7.4 Syntax------------There are different aspects of the CRIS assembly syntax.* Menu:* CRIS-Chars:: Special Characters* CRIS-Pic:: Position-Independent Code Symbols* CRIS-Regs:: Register Names* CRIS-Pseudos:: Assembler DirectivesFile: as.info, Node: CRIS-Chars, Next: CRIS-Pic, Up: CRIS-Syntax9.7.4.1 Special Characters..........................The character `#' is a line comment character. It starts a comment ifand only if it is placed at the beginning of a line.A `;' character starts a comment anywhere on the line, causing allcharacters up to the end of the line to be ignored.A `@' character is handled as a line separator equivalent to alogical new-line character (except in a comment), so separateinstructions can be specified on a single line.File: as.info, Node: CRIS-Pic, Next: CRIS-Regs, Prev: CRIS-Chars, Up: CRIS-Syntax9.7.4.2 Symbols in position-independent code............................................When generating position-independent code (SVR4 PIC) for use incris-axis-linux-gnu or crisv32-axis-linux-gnu shared libraries, symbolsuffixes are used to specify what kind of run-time symbol lookup willbe used, expressed in the object as different _relocation types_.Usually, all absolute symbol values must be located in a table, the_global offset table_, leaving the code position-independent;independent of values of global symbols and independent of the addressof the code. The suffix modifies the value of the symbol, into forexample an index into the global offset table where the real symbolvalue is entered, or a PC-relative value, or a value relative to thestart of the global offset table. All symbol suffixes start with thecharacter `:' (omitted in the list below). Every symbol use in code ora read-only section must therefore have a PIC suffix to enable a usefulshared library to be created. Usually, these constructs must not beused with an additive constant offset as is usually allowed, i.e. no 4as in `symbol + 4' is allowed. This restriction is checked atlink-time, not at assembly-time.`GOT'Attaching this suffix to a symbol in an instruction causes thesymbol to be entered into the global offset table. The value is a32-bit index for that symbol into the global offset table. Thename of the corresponding relocation is `R_CRIS_32_GOT'. Example:`move.d [$r0+extsym:GOT],$r9'`GOT16'Same as for `GOT', but the value is a 16-bit index into the globaloffset table. The corresponding relocation is `R_CRIS_16_GOT'.Example: `move.d [$r0+asymbol:GOT16],$r10'`PLT'This suffix is used for function symbols. It causes a _procedurelinkage table_, an array of code stubs, to be created at the timethe shared object is created or linked against, together with aglobal offset table entry. The value is a pc-relative offset tothe corresponding stub code in the procedure linkage table. Thisarrangement causes the run-time symbol resolver to be called tolook up and set the value of the symbol the first time thefunction is called (at latest; depending environment variables).It is only safe to leave the symbol unresolved this way if allreferences are function calls. The name of the relocation is`R_CRIS_32_PLT_PCREL'. Example: `add.d fnname:PLT,$pc'`PLTG'Like PLT, but the value is relative to the beginning of the globaloffset table. The relocation is `R_CRIS_32_PLT_GOTREL'. Example:`move.d fnname:PLTG,$r3'`GOTPLT'Similar to `PLT', but the value of the symbol is a 32-bit indexinto the global offset table. This is somewhat of a mix betweenthe effect of the `GOT' and the `PLT' suffix; the difference to`GOT' is that there will be a procedure linkage table entrycreated, and that the symbol is assumed to be a function entry andwill be resolved by the run-time resolver as with `PLT'. Therelocation is `R_CRIS_32_GOTPLT'. Example: `jsr[$r0+fnname:GOTPLT]'`GOTPLT16'A variant of `GOTPLT' giving a 16-bit value. Its relocation nameis `R_CRIS_16_GOTPLT'. Example: `jsr [$r0+fnname:GOTPLT16]'`GOTOFF'This suffix must only be attached to a local symbol, but may beused in an expression adding an offset. The value is the addressof the symbol relative to the start of the global offset table.The relocation name is `R_CRIS_32_GOTREL'. Example: `move.d[$r0+localsym:GOTOFF],r3'File: as.info, Node: CRIS-Regs, Next: CRIS-Pseudos, Prev: CRIS-Pic, Up: CRIS-Syntax9.7.4.3 Register names......................A `$' character may always prefix a general or special register name inan instruction operand but is mandatory when the option`--no-underscore' is specified or when the `.syntax register_prefix'directive is in effect (*note crisnous::). Register names arecase-insensitive.File: as.info, Node: CRIS-Pseudos, Prev: CRIS-Regs, Up: CRIS-Syntax9.7.4.4 Assembler Directives............................There are a few CRIS-specific pseudo-directives in addition to thegeneric ones. *Note Pseudo Ops::. Constants emitted bypseudo-directives are in little-endian order for CRIS. There is nosupport for floating-point-specific directives for CRIS.`.dword EXPRESSIONS'The `.dword' directive is a synonym for `.int', expecting zero ormore EXPRESSIONS, separated by commas. For each expression, a32-bit little-endian constant is emitted.`.syntax ARGUMENT'The `.syntax' directive takes as ARGUMENT one of the followingcase-sensitive choices.`no_register_prefix'The `.syntax no_register_prefix' directive makes a `$'character prefix on all registers optional. It overrides aprevious setting, including the corresponding effect of theoption `--no-underscore'. If this directive is used whenordinary symbols do not have a `_' character prefix, caremust be taken to avoid ambiguities whether an operand is aregister or a symbol; using symbols with names the same asgeneral or special registers then invoke undefined behavior.`register_prefix'This directive makes a `$' character prefix on all registersmandatory. It overrides a previous setting, including thecorresponding effect of the option `--underscore'.`leading_underscore'This is an assertion directive, emitting an error if the`--no-underscore' option is in effect.`no_leading_underscore'This is the opposite of the `.syntax leading_underscore'directive and emits an error if the option `--underscore' isin effect.`.arch ARGUMENT'This is an assertion directive, giving an error if the specifiedARGUMENT is not the same as the specified or default value for the`--march=ARCHITECTURE' option (*note march-option::).File: as.info, Node: D10V-Dependent, Next: D30V-Dependent, Prev: CRIS-Dependent, Up: Machine Dependencies9.8 D10V Dependent Features===========================* Menu:* D10V-Opts:: D10V Options* D10V-Syntax:: Syntax* D10V-Float:: Floating Point* D10V-Opcodes:: OpcodesFile: as.info, Node: D10V-Opts, Next: D10V-Syntax, Up: D10V-Dependent9.8.1 D10V Options------------------The Mitsubishi D10V version of `as' has a few machine dependent options.`-O'The D10V can often execute two sub-instructions in parallel. Whenthis option is used, `as' will attempt to optimize its output bydetecting when instructions can be executed in parallel.`--nowarnswap'To optimize execution performance, `as' will sometimes swap theorder of instructions. Normally this generates a warning. Whenthis option is used, no warning will be generated wheninstructions are swapped.`--gstabs-packing'`--no-gstabs-packing'`as' packs adjacent short instructions into a single packedinstruction. `--no-gstabs-packing' turns instruction packing off if`--gstabs' is specified as well; `--gstabs-packing' (the default)turns instruction packing on even when `--gstabs' is specified.File: as.info, Node: D10V-Syntax, Next: D10V-Float, Prev: D10V-Opts, Up: D10V-Dependent9.8.2 Syntax------------The D10V syntax is based on the syntax in Mitsubishi's D10Varchitecture manual. The differences are detailed below.* Menu:* D10V-Size:: Size Modifiers* D10V-Subs:: Sub-Instructions* D10V-Chars:: Special Characters* D10V-Regs:: Register Names* D10V-Addressing:: Addressing Modes* D10V-Word:: @WORD ModifierFile: as.info, Node: D10V-Size, Next: D10V-Subs, Up: D10V-Syntax9.8.2.1 Size Modifiers......................The D10V version of `as' uses the instruction names in the D10VArchitecture Manual. However, the names in the manual are sometimesambiguous. There are instruction names that can assemble to a short orlong form opcode. How does the assembler pick the correct form? `as'will always pick the smallest form if it can. When dealing with asymbol that is not defined yet when a line is being assembled, it willalways use the long form. If you need to force the assembler to useeither the short or long form of the instruction, you can append either`.s' (short) or `.l' (long) to it. For example, if you are writing anassembly program and you want to do a branch to a symbol that isdefined later in your program, you can write `bra.s foo'. Objdumpand GDB will always append `.s' or `.l' to instructions which have bothshort and long forms.File: as.info, Node: D10V-Subs, Next: D10V-Chars, Prev: D10V-Size, Up: D10V-Syntax9.8.2.2 Sub-Instructions........................The D10V assembler takes as input a series of instructions, eitherone-per-line, or in the special two-per-line format described in thenext section. Some of these instructions will be short-form orsub-instructions. These sub-instructions can be packed into a singleinstruction. The assembler will do this automatically. It will alsodetect when it should not pack instructions. For example, when a labelis defined, the next instruction will never be packaged with theprevious one. Whenever a branch and link instruction is called, itwill not be packaged with the next instruction so the return addresswill be valid. Nops are automatically inserted when necessary.If you do not want the assembler automatically making thesedecisions, you can control the packaging and execution type (parallelor sequential) with the special execution symbols described in the nextsection.File: as.info, Node: D10V-Chars, Next: D10V-Regs, Prev: D10V-Subs, Up: D10V-Syntax9.8.2.3 Special Characters..........................`;' and `#' are the line comment characters. Sub-instructions may beexecuted in order, in reverse-order, or in parallel. Instructionslisted in the standard one-per-line format will be executedsequentially. To specify the executing order, use the followingsymbols:`->'Sequential with instruction on the left first.`<-'Sequential with instruction on the right first.`||'ParallelThe D10V syntax allows either one instruction per line, oneinstruction per line with the execution symbol, or two instructions perline. For example`abs a1 -> abs r0'Execute these sequentially. The instruction on the right is inthe right container and is executed second.`abs r0 <- abs a1'Execute these reverse-sequentially. The instruction on the rightis in the right container, and is executed first.`ld2w r2,@r8+ || mac a0,r0,r7'Execute these in parallel.`ld2w r2,@r8+ ||'`mac a0,r0,r7'Two-line format. Execute these in parallel.`ld2w r2,@r8+'`mac a0,r0,r7'Two-line format. Execute these sequentially. Assembler will putthem in the proper containers.`ld2w r2,@r8+ ->'`mac a0,r0,r7'Two-line format. Execute these sequentially. Same as above butsecond instruction will always go into right container.Since `$' has no special meaning, you may use it in symbol names.File: as.info, Node: D10V-Regs, Next: D10V-Addressing, Prev: D10V-Chars, Up: D10V-Syntax9.8.2.4 Register Names......................You can use the predefined symbols `r0' through `r15' to refer to theD10V registers. You can also use `sp' as an alias for `r15'. Theaccumulators are `a0' and `a1'. There are special register-pair namesthat may optionally be used in opcodes that require even-numberedregisters. Register names are not case sensitive.Register Pairs`r0-r1'`r2-r3'`r4-r5'`r6-r7'`r8-r9'`r10-r11'`r12-r13'`r14-r15'The D10V also has predefined symbols for these control registers andstatus bits:`psw'Processor Status Word`bpsw'Backup Processor Status Word`pc'Program Counter`bpc'Backup Program Counter`rpt_c'Repeat Count`rpt_s'Repeat Start address`rpt_e'Repeat End address`mod_s'Modulo Start address`mod_e'Modulo End address`iba'Instruction Break Address`f0'Flag 0`f1'Flag 1`c'Carry flagFile: as.info, Node: D10V-Addressing, Next: D10V-Word, Prev: D10V-Regs, Up: D10V-Syntax9.8.2.5 Addressing Modes........................`as' understands the following addressing modes for the D10V. `RN' inthe following refers to any of the numbered registers, but _not_ thecontrol registers.`RN'Register direct`@RN'Register indirect`@RN+'Register indirect with post-increment`@RN-'Register indirect with post-decrement`@-SP'Register indirect with pre-decrement`@(DISP, RN)'Register indirect with displacement`ADDR'PC relative address (for branch or rep).`#IMM'Immediate data (the `#' is optional and ignored)File: as.info, Node: D10V-Word, Prev: D10V-Addressing, Up: D10V-Syntax9.8.2.6 @WORD Modifier......................Any symbol followed by `@word' will be replaced by the symbol's valueshifted right by 2. This is used in situations such as loading aregister with the address of a function (or any other code fragment).For example, if you want to load a register with the location of thefunction `main' then jump to that function, you could do it as follows:ldi r2, main@wordjmp r2File: as.info, Node: D10V-Float, Next: D10V-Opcodes, Prev: D10V-Syntax, Up: D10V-Dependent9.8.3 Floating Point--------------------The D10V has no hardware floating point, but the `.float' and `.double'directives generates IEEE floating-point numbers for compatibility withother development tools.File: as.info, Node: D10V-Opcodes, Prev: D10V-Float, Up: D10V-Dependent9.8.4 Opcodes-------------For detailed information on the D10V machine instruction set, see `D10VArchitecture: A VLIW Microprocessor for Multimedia Applications'(Mitsubishi Electric Corp.). `as' implements all the standard D10Vopcodes. The only changes are those described in the section on sizemodifiersFile: as.info, Node: D30V-Dependent, Next: H8/300-Dependent, Prev: D10V-Dependent, Up: Machine Dependencies9.9 D30V Dependent Features===========================* Menu:* D30V-Opts:: D30V Options* D30V-Syntax:: Syntax* D30V-Float:: Floating Point* D30V-Opcodes:: OpcodesFile: as.info, Node: D30V-Opts, Next: D30V-Syntax, Up: D30V-Dependent9.9.1 D30V Options------------------The Mitsubishi D30V version of `as' has a few machine dependent options.`-O'The D30V can often execute two sub-instructions in parallel. Whenthis option is used, `as' will attempt to optimize its output bydetecting when instructions can be executed in parallel.`-n'When this option is used, `as' will issue a warning every time itadds a nop instruction.`-N'When this option is used, `as' will issue a warning if it needs toinsert a nop after a 32-bit multiply before a load or 16-bitmultiply instruction.File: as.info, Node: D30V-Syntax, Next: D30V-Float, Prev: D30V-Opts, Up: D30V-Dependent9.9.2 Syntax------------The D30V syntax is based on the syntax in Mitsubishi's D30Varchitecture manual. The differences are detailed below.* Menu:* D30V-Size:: Size Modifiers* D30V-Subs:: Sub-Instructions* D30V-Chars:: Special Characters* D30V-Guarded:: Guarded Execution* D30V-Regs:: Register Names* D30V-Addressing:: Addressing ModesFile: as.info, Node: D30V-Size, Next: D30V-Subs, Up: D30V-Syntax9.9.2.1 Size Modifiers......................The D30V version of `as' uses the instruction names in the D30VArchitecture Manual. However, the names in the manual are sometimesambiguous. There are instruction names that can assemble to a short orlong form opcode. How does the assembler pick the correct form? `as'will always pick the smallest form if it can. When dealing with asymbol that is not defined yet when a line is being assembled, it willalways use the long form. If you need to force the assembler to useeither the short or long form of the instruction, you can append either`.s' (short) or `.l' (long) to it. For example, if you are writing anassembly program and you want to do a branch to a symbol that isdefined later in your program, you can write `bra.s foo'. Objdump andGDB will always append `.s' or `.l' to instructions which have bothshort and long forms.File: as.info, Node: D30V-Subs, Next: D30V-Chars, Prev: D30V-Size, Up: D30V-Syntax9.9.2.2 Sub-Instructions........................The D30V assembler takes as input a series of instructions, eitherone-per-line, or in the special two-per-line format described in thenext section. Some of these instructions will be short-form orsub-instructions. These sub-instructions can be packed into a singleinstruction. The assembler will do this automatically. It will alsodetect when it should not pack instructions. For example, when a labelis defined, the next instruction will never be packaged with theprevious one. Whenever a branch and link instruction is called, itwill not be packaged with the next instruction so the return addresswill be valid. Nops are automatically inserted when necessary.If you do not want the assembler automatically making thesedecisions, you can control the packaging and execution type (parallelor sequential) with the special execution symbols described in the nextsection.File: as.info, Node: D30V-Chars, Next: D30V-Guarded, Prev: D30V-Subs, Up: D30V-Syntax9.9.2.3 Special Characters..........................`;' and `#' are the line comment characters. Sub-instructions may beexecuted in order, in reverse-order, or in parallel. Instructionslisted in the standard one-per-line format will be executedsequentially unless you use the `-O' option.To specify the executing order, use the following symbols:`->'Sequential with instruction on the left first.`<-'Sequential with instruction on the right first.`||'ParallelThe D30V syntax allows either one instruction per line, oneinstruction per line with the execution symbol, or two instructions perline. For example`abs r2,r3 -> abs r4,r5'Execute these sequentially. The instruction on the right is inthe right container and is executed second.`abs r2,r3 <- abs r4,r5'Execute these reverse-sequentially. The instruction on the rightis in the right container, and is executed first.`abs r2,r3 || abs r4,r5'Execute these in parallel.`ldw r2,@(r3,r4) ||'`mulx r6,r8,r9'Two-line format. Execute these in parallel.`mulx a0,r8,r9'`stw r2,@(r3,r4)'Two-line format. Execute these sequentially unless `-O' option isused. If the `-O' option is used, the assembler will determine ifthe instructions could be done in parallel (the above twoinstructions can be done in parallel), and if so, emit them asparallel instructions. The assembler will put them in the propercontainers. In the above example, the assembler will put the`stw' instruction in left container and the `mulx' instruction inthe right container.`stw r2,@(r3,r4) ->'`mulx a0,r8,r9'Two-line format. Execute the `stw' instruction followed by the`mulx' instruction sequentially. The first instruction goes in theleft container and the second instruction goes into rightcontainer. The assembler will give an error if the machineordering constraints are violated.`stw r2,@(r3,r4) <-'`mulx a0,r8,r9'Same as previous example, except that the `mulx' instruction isexecuted before the `stw' instruction.Since `$' has no special meaning, you may use it in symbol names.File: as.info, Node: D30V-Guarded, Next: D30V-Regs, Prev: D30V-Chars, Up: D30V-Syntax9.9.2.4 Guarded Execution.........................`as' supports the full range of guarded execution directives for eachinstruction. Just append the directive after the instruction proper.The directives are:`/tx'Execute the instruction if flag f0 is true.`/fx'Execute the instruction if flag f0 is false.`/xt'Execute the instruction if flag f1 is true.`/xf'Execute the instruction if flag f1 is false.`/tt'Execute the instruction if both flags f0 and f1 are true.`/tf'Execute the instruction if flag f0 is true and flag f1 is false.File: as.info, Node: D30V-Regs, Next: D30V-Addressing, Prev: D30V-Guarded, Up: D30V-Syntax9.9.2.5 Register Names......................You can use the predefined symbols `r0' through `r63' to refer to theD30V registers. You can also use `sp' as an alias for `r63' and `link'as an alias for `r62'. The accumulators are `a0' and `a1'.The D30V also has predefined symbols for these control registers andstatus bits:`psw'Processor Status Word`bpsw'Backup Processor Status Word`pc'Program Counter`bpc'Backup Program Counter`rpt_c'Repeat Count`rpt_s'Repeat Start address`rpt_e'Repeat End address`mod_s'Modulo Start address`mod_e'Modulo End address`iba'Instruction Break Address`f0'Flag 0`f1'Flag 1`f2'Flag 2`f3'Flag 3`f4'Flag 4`f5'Flag 5`f6'Flag 6`f7'Flag 7`s'Same as flag 4 (saturation flag)`v'Same as flag 5 (overflow flag)`va'Same as flag 6 (sticky overflow flag)`c'Same as flag 7 (carry/borrow flag)`b'Same as flag 7 (carry/borrow flag)File: as.info, Node: D30V-Addressing, Prev: D30V-Regs, Up: D30V-Syntax9.9.2.6 Addressing Modes........................`as' understands the following addressing modes for the D30V. `RN' inthe following refers to any of the numbered registers, but _not_ thecontrol registers.`RN'Register direct`@RN'Register indirect`@RN+'Register indirect with post-increment`@RN-'Register indirect with post-decrement`@-SP'Register indirect with pre-decrement`@(DISP, RN)'Register indirect with displacement`ADDR'PC relative address (for branch or rep).`#IMM'Immediate data (the `#' is optional and ignored)File: as.info, Node: D30V-Float, Next: D30V-Opcodes, Prev: D30V-Syntax, Up: D30V-Dependent9.9.3 Floating Point--------------------The D30V has no hardware floating point, but the `.float' and `.double'directives generates IEEE floating-point numbers for compatibility withother development tools.File: as.info, Node: D30V-Opcodes, Prev: D30V-Float, Up: D30V-Dependent9.9.4 Opcodes-------------For detailed information on the D30V machine instruction set, see `D30VArchitecture: A VLIW Microprocessor for Multimedia Applications'(Mitsubishi Electric Corp.). `as' implements all the standard D30Vopcodes. The only changes are those described in the section on sizemodifiersFile: as.info, Node: H8/300-Dependent, Next: HPPA-Dependent, Prev: D30V-Dependent, Up: Machine Dependencies9.10 H8/300 Dependent Features==============================* Menu:* H8/300 Options:: Options* H8/300 Syntax:: Syntax* H8/300 Floating Point:: Floating Point* H8/300 Directives:: H8/300 Machine Directives* H8/300 Opcodes:: OpcodesFile: as.info, Node: H8/300 Options, Next: H8/300 Syntax, Up: H8/300-Dependent9.10.1 Options--------------The Renesas H8/300 version of `as' has one machine-dependent option:`-h-tick-hex'Support H'00 style hex constants in addition to 0x00 style.File: as.info, Node: H8/300 Syntax, Next: H8/300 Floating Point, Prev: H8/300 Options, Up: H8/300-Dependent9.10.2 Syntax-------------* Menu:* H8/300-Chars:: Special Characters* H8/300-Regs:: Register Names* H8/300-Addressing:: Addressing ModesFile: as.info, Node: H8/300-Chars, Next: H8/300-Regs, Up: H8/300 Syntax9.10.2.1 Special Characters...........................`;' is the line comment character.`$' can be used instead of a newline to separate statements.Therefore _you may not use `$' in symbol names_ on the H8/300.File: as.info, Node: H8/300-Regs, Next: H8/300-Addressing, Prev: H8/300-Chars, Up: H8/300 Syntax9.10.2.2 Register Names.......................You can use predefined symbols of the form `rNh' and `rNl' to refer tothe H8/300 registers as sixteen 8-bit general-purpose registers. N isa digit from `0' to `7'); for instance, both `r0h' and `r7l' are validregister names.You can also use the eight predefined symbols `rN' to refer to theH8/300 registers as 16-bit registers (you must use this form foraddressing).On the H8/300H, you can also use the eight predefined symbols `erN'(`er0' ... `er7') to refer to the 32-bit general purpose registers.The two control registers are called `pc' (program counter; a 16-bitregister, except on the H8/300H where it is 24 bits) and `ccr'(condition code register; an 8-bit register). `r7' is used as thestack pointer, and can also be called `sp'.File: as.info, Node: H8/300-Addressing, Prev: H8/300-Regs, Up: H8/300 Syntax9.10.2.3 Addressing Modes.........................as understands the following addressing modes for the H8/300:`rN'Register direct`@rN'Register indirect`@(D, rN)'`@(D:16, rN)'`@(D:24, rN)'Register indirect: 16-bit or 24-bit displacement D from registerN. (24-bit displacements are only meaningful on the H8/300H.)`@rN+'Register indirect with post-increment`@-rN'Register indirect with pre-decrement``@'AA'``@'AA:8'``@'AA:16'``@'AA:24'Absolute address `aa'. (The address size `:24' only makes senseon the H8/300H.)`#XX'`#XX:8'`#XX:16'`#XX:32'Immediate data XX. You may specify the `:8', `:16', or `:32' forclarity, if you wish; but `as' neither requires this nor usesit--the data size required is taken from context.``@'`@'AA'``@'`@'AA:8'Memory indirect. You may specify the `:8' for clarity, if youwish; but `as' neither requires this nor uses it.File: as.info, Node: H8/300 Floating Point, Next: H8/300 Directives, Prev: H8/300 Syntax, Up: H8/300-Dependent9.10.3 Floating Point---------------------The H8/300 family has no hardware floating point, but the `.float'directive generates IEEE floating-point numbers for compatibility withother development tools.File: as.info, Node: H8/300 Directives, Next: H8/300 Opcodes, Prev: H8/300 Floating Point, Up: H8/300-Dependent9.10.4 H8/300 Machine Directives--------------------------------`as' has the following machine-dependent directives for the H8/300:`.h8300h'Recognize and emit additional instructions for the H8/300Hvariant, and also make `.int' emit 32-bit numbers rather than theusual (16-bit) for the H8/300 family.`.h8300s'Recognize and emit additional instructions for the H8S variant, andalso make `.int' emit 32-bit numbers rather than the usual (16-bit)for the H8/300 family.`.h8300hn'Recognize and emit additional instructions for the H8/300H variantin normal mode, and also make `.int' emit 32-bit numbers ratherthan the usual (16-bit) for the H8/300 family.`.h8300sn'Recognize and emit additional instructions for the H8S variant innormal mode, and also make `.int' emit 32-bit numbers rather thanthe usual (16-bit) for the H8/300 family.On the H8/300 family (including the H8/300H) `.word' directivesgenerate 16-bit numbers.File: as.info, Node: H8/300 Opcodes, Prev: H8/300 Directives, Up: H8/300-Dependent9.10.5 Opcodes--------------For detailed information on the H8/300 machine instruction set, see`H8/300 Series Programming Manual'. For information specific to theH8/300H, see `H8/300H Series Programming Manual' (Renesas).`as' implements all the standard H8/300 opcodes. No additionalpseudo-instructions are needed on this family.The following table summarizes the H8/300 opcodes, and theirarguments. Entries marked `*' are opcodes used only on the H8/300H.Legend:Rs source registerRd destination registerabs absolute addressimm immediate datadisp:N N-bit displacement from a registerpcrel:N N-bit displacement relative to program counteradd.b #imm,rd * andc #imm,ccradd.b rs,rd band #imm,rdadd.w rs,rd band #imm,@rd* add.w #imm,rd band #imm,@abs:8* add.l rs,rd bra pcrel:8* add.l #imm,rd * bra pcrel:16adds #imm,rd bt pcrel:8addx #imm,rd * bt pcrel:16addx rs,rd brn pcrel:8and.b #imm,rd * brn pcrel:16and.b rs,rd bf pcrel:8* and.w rs,rd * bf pcrel:16* and.w #imm,rd bhi pcrel:8* and.l #imm,rd * bhi pcrel:16* and.l rs,rd bls pcrel:8* bls pcrel:16 bld #imm,rdbcc pcrel:8 bld #imm,@rd* bcc pcrel:16 bld #imm,@abs:8bhs pcrel:8 bnot #imm,rd* bhs pcrel:16 bnot #imm,@rdbcs pcrel:8 bnot #imm,@abs:8* bcs pcrel:16 bnot rs,rdblo pcrel:8 bnot rs,@rd* blo pcrel:16 bnot rs,@abs:8bne pcrel:8 bor #imm,rd* bne pcrel:16 bor #imm,@rdbeq pcrel:8 bor #imm,@abs:8* beq pcrel:16 bset #imm,rdbvc pcrel:8 bset #imm,@rd* bvc pcrel:16 bset #imm,@abs:8bvs pcrel:8 bset rs,rd* bvs pcrel:16 bset rs,@rdbpl pcrel:8 bset rs,@abs:8* bpl pcrel:16 bsr pcrel:8bmi pcrel:8 bsr pcrel:16* bmi pcrel:16 bst #imm,rdbge pcrel:8 bst #imm,@rd* bge pcrel:16 bst #imm,@abs:8blt pcrel:8 btst #imm,rd* blt pcrel:16 btst #imm,@rdbgt pcrel:8 btst #imm,@abs:8* bgt pcrel:16 btst rs,rdble pcrel:8 btst rs,@rd* ble pcrel:16 btst rs,@abs:8bclr #imm,rd bxor #imm,rdbclr #imm,@rd bxor #imm,@rdbclr #imm,@abs:8 bxor #imm,@abs:8bclr rs,rd cmp.b #imm,rdbclr rs,@rd cmp.b rs,rdbclr rs,@abs:8 cmp.w rs,rdbiand #imm,rd cmp.w rs,rdbiand #imm,@rd * cmp.w #imm,rdbiand #imm,@abs:8 * cmp.l #imm,rdbild #imm,rd * cmp.l rs,rdbild #imm,@rd daa rsbild #imm,@abs:8 das rsbior #imm,rd dec.b rsbior #imm,@rd * dec.w #imm,rdbior #imm,@abs:8 * dec.l #imm,rdbist #imm,rd divxu.b rs,rdbist #imm,@rd * divxu.w rs,rdbist #imm,@abs:8 * divxs.b rs,rdbixor #imm,rd * divxs.w rs,rdbixor #imm,@rd eepmovbixor #imm,@abs:8 * eepmovw* exts.w rd mov.w rs,@abs:16* exts.l rd * mov.l #imm,rd* extu.w rd * mov.l rs,rd* extu.l rd * mov.l @rs,rdinc rs * mov.l @(disp:16,rs),rd* inc.w #imm,rd * mov.l @(disp:24,rs),rd* inc.l #imm,rd * mov.l @rs+,rdjmp @rs * mov.l @abs:16,rdjmp abs * mov.l @abs:24,rdjmp @@abs:8 * mov.l rs,@rdjsr @rs * mov.l rs,@(disp:16,rd)jsr abs * mov.l rs,@(disp:24,rd)jsr @@abs:8 * mov.l rs,@-rdldc #imm,ccr * mov.l rs,@abs:16ldc rs,ccr * mov.l rs,@abs:24* ldc @abs:16,ccr movfpe @abs:16,rd* ldc @abs:24,ccr movtpe rs,@abs:16* ldc @(disp:16,rs),ccr mulxu.b rs,rd* ldc @(disp:24,rs),ccr * mulxu.w rs,rd* ldc @rs+,ccr * mulxs.b rs,rd* ldc @rs,ccr * mulxs.w rs,rd* mov.b @(disp:24,rs),rd neg.b rs* mov.b rs,@(disp:24,rd) * neg.w rsmov.b @abs:16,rd * neg.l rsmov.b rs,rd nopmov.b @abs:8,rd not.b rsmov.b rs,@abs:8 * not.w rsmov.b rs,rd * not.l rsmov.b #imm,rd or.b #imm,rdmov.b @rs,rd or.b rs,rdmov.b @(disp:16,rs),rd * or.w #imm,rdmov.b @rs+,rd * or.w rs,rdmov.b @abs:8,rd * or.l #imm,rdmov.b rs,@rd * or.l rs,rdmov.b rs,@(disp:16,rd) orc #imm,ccrmov.b rs,@-rd pop.w rsmov.b rs,@abs:8 * pop.l rsmov.w rs,@rd push.w rs* mov.w @(disp:24,rs),rd * push.l rs* mov.w rs,@(disp:24,rd) rotl.b rs* mov.w @abs:24,rd * rotl.w rs* mov.w rs,@abs:24 * rotl.l rsmov.w rs,rd rotr.b rsmov.w #imm,rd * rotr.w rsmov.w @rs,rd * rotr.l rsmov.w @(disp:16,rs),rd rotxl.b rsmov.w @rs+,rd * rotxl.w rsmov.w @abs:16,rd * rotxl.l rsmov.w rs,@(disp:16,rd) rotxr.b rsmov.w rs,@-rd * rotxr.w rs* rotxr.l rs * stc ccr,@(disp:24,rd)bpt * stc ccr,@-rdrte * stc ccr,@abs:16rts * stc ccr,@abs:24shal.b rs sub.b rs,rd* shal.w rs sub.w rs,rd* shal.l rs * sub.w #imm,rdshar.b rs * sub.l rs,rd* shar.w rs * sub.l #imm,rd* shar.l rs subs #imm,rdshll.b rs subx #imm,rd* shll.w rs subx rs,rd* shll.l rs * trapa #immshlr.b rs xor #imm,rd* shlr.w rs xor rs,rd* shlr.l rs * xor.w #imm,rdsleep * xor.w rs,rdstc ccr,rd * xor.l #imm,rd* stc ccr,@rs * xor.l rs,rd* stc ccr,@(disp:16,rd) xorc #imm,ccrFour H8/300 instructions (`add', `cmp', `mov', `sub') are definedwith variants using the suffixes `.b', `.w', and `.l' to specify thesize of a memory operand. `as' supports these suffixes, but does notrequire them; since one of the operands is always a register, `as' candeduce the correct size.For example, since `r0' refers to a 16-bit register,mov r0,@foois equivalent tomov.w r0,@fooIf you use the size suffixes, `as' issues a warning when the suffixand the register size do not match.File: as.info, Node: HPPA-Dependent, Next: ESA/390-Dependent, Prev: H8/300-Dependent, Up: Machine Dependencies9.11 HPPA Dependent Features============================* Menu:* HPPA Notes:: Notes* HPPA Options:: Options* HPPA Syntax:: Syntax* HPPA Floating Point:: Floating Point* HPPA Directives:: HPPA Machine Directives* HPPA Opcodes:: OpcodesFile: as.info, Node: HPPA Notes, Next: HPPA Options, Up: HPPA-Dependent9.11.1 Notes------------As a back end for GNU CC `as' has been throughly tested and should workextremely well. We have tested it only minimally on hand writtenassembly code and no one has tested it much on the assembly output fromthe HP compilers.The format of the debugging sections has changed since the original`as' port (version 1.3X) was released; therefore, you must rebuild allHPPA objects and libraries with the new assembler so that you can debugthe final executable.The HPPA `as' port generates a small subset of the relocationsavailable in the SOM and ELF object file formats. Additional relocationsupport will be added as it becomes necessary.File: as.info, Node: HPPA Options, Next: HPPA Syntax, Prev: HPPA Notes, Up: HPPA-Dependent9.11.2 Options--------------`as' has no machine-dependent command-line options for the HPPA.File: as.info, Node: HPPA Syntax, Next: HPPA Floating Point, Prev: HPPA Options, Up: HPPA-Dependent9.11.3 Syntax-------------The assembler syntax closely follows the HPPA instruction set referencemanual; assembler directives and general syntax closely follow the HPPAassembly language reference manual, with a few noteworthy differences.First, a colon may immediately follow a label definition. This issimply for compatibility with how most assembly language programmerswrite code.Some obscure expression parsing problems may affect hand writtencode which uses the `spop' instructions, or code which makes significantuse of the `!' line separator.`as' is much less forgiving about missing arguments and othersimilar oversights than the HP assembler. `as' notifies you of missingarguments as syntax errors; this is regarded as a feature, not a bug.Finally, `as' allows you to use an external symbol withoutexplicitly importing the symbol. _Warning:_ in the future this will bean error for HPPA targets.Special characters for HPPA targets include:`;' is the line comment character.`!' can be used instead of a newline to separate statements.Since `$' has no special meaning, you may use it in symbol names.File: as.info, Node: HPPA Floating Point, Next: HPPA Directives, Prev: HPPA Syntax, Up: HPPA-Dependent9.11.4 Floating Point---------------------The HPPA family uses IEEE floating-point numbers.File: as.info, Node: HPPA Directives, Next: HPPA Opcodes, Prev: HPPA Floating Point, Up: HPPA-Dependent9.11.5 HPPA Assembler Directives--------------------------------`as' for the HPPA supports many additional directives for compatibilitywith the native assembler. This section describes them only briefly.For detailed information on HPPA-specific assembler directives, see`HP9000 Series 800 Assembly Language Reference Manual' (HP 92432-90001).`as' does _not_ support the following assembler directives describedin the HP manual:.endm .liston.enter .locct.leave .macro.listoffBeyond those implemented for compatibility, `as' supports oneadditional assembler directive for the HPPA: `.param'. It conveysregister argument locations for static functions. Its syntax closelyfollows the `.export' directive.These are the additional directives in `as' for the HPPA:`.block N'`.blockz N'Reserve N bytes of storage, and initialize them to zero.`.call'Mark the beginning of a procedure call. Only the special casewith _no arguments_ is allowed.`.callinfo [ PARAM=VALUE, ... ] [ FLAG, ... ]'Specify a number of parameters and flags that define theenvironment for a procedure.PARAM may be any of `frame' (frame size), `entry_gr' (end ofgeneral register range), `entry_fr' (end of float register range),`entry_sr' (end of space register range).The values for FLAG are `calls' or `caller' (proc hassubroutines), `no_calls' (proc does not call subroutines),`save_rp' (preserve return pointer), `save_sp' (proc preservesstack pointer), `no_unwind' (do not unwind this proc), `hpux_int'(proc is interrupt routine).`.code'Assemble into the standard section called `$TEXT$', subsection`$CODE$'.`.copyright "STRING"'In the SOM object format, insert STRING into the object code,marked as a copyright string.`.copyright "STRING"'In the ELF object format, insert STRING into the object code,marked as a version string.`.enter'Not yet supported; the assembler rejects programs containing thisdirective.`.entry'Mark the beginning of a procedure.`.exit'Mark the end of a procedure.`.export NAME [ ,TYP ] [ ,PARAM=R ]'Make a procedure NAME available to callers. TYP, if present, mustbe one of `absolute', `code' (ELF only, not SOM), `data', `entry',`data', `entry', `millicode', `plabel', `pri_prog', or `sec_prog'.PARAM, if present, provides either relocation information for theprocedure arguments and result, or a privilege level. PARAM may be`argwN' (where N ranges from `0' to `3', and indicates one of fourone-word arguments); `rtnval' (the procedure's result); or`priv_lev' (privilege level). For arguments or the result, Rspecifies how to relocate, and must be one of `no' (notrelocatable), `gr' (argument is in general register), `fr' (infloating point register), or `fu' (upper half of float register).For `priv_lev', R is an integer.`.half N'Define a two-byte integer constant N; synonym for the portable`as' directive `.short'.`.import NAME [ ,TYP ]'Converse of `.export'; make a procedure available to call. Thearguments use the same conventions as the first two arguments for`.export'.`.label NAME'Define NAME as a label for the current assembly location.`.leave'Not yet supported; the assembler rejects programs containing thisdirective.`.origin LC'Advance location counter to LC. Synonym for the `as' portabledirective `.org'.`.param NAME [ ,TYP ] [ ,PARAM=R ]'Similar to `.export', but used for static procedures.`.proc'Use preceding the first statement of a procedure.`.procend'Use following the last statement of a procedure.`LABEL .reg EXPR'Synonym for `.equ'; define LABEL with the absolute expression EXPRas its value.`.space SECNAME [ ,PARAMS ]'Switch to section SECNAME, creating a new section by that name ifnecessary. You may only use PARAMS when creating a new section,not when switching to an existing one. SECNAME may identify asection by number rather than by name.If specified, the list PARAMS declares attributes of the section,identified by keywords. The keywords recognized are `spnum=EXP'(identify this section by the number EXP, an absolute expression),`sort=EXP' (order sections according to this sort key when linking;EXP is an absolute expression), `unloadable' (section contains noloadable data), `notdefined' (this section defined elsewhere), and`private' (data in this section not available to other programs).`.spnum SECNAM'Allocate four bytes of storage, and initialize them with thesection number of the section named SECNAM. (You can define thesection number with the HPPA `.space' directive.)`.string "STR"'Copy the characters in the string STR to the object file. *NoteStrings: Strings, for information on escape sequences you can usein `as' strings._Warning!_ The HPPA version of `.string' differs from the usual`as' definition: it does _not_ write a zero byte after copying STR.`.stringz "STR"'Like `.string', but appends a zero byte after copying STR to objectfile.`.subspa NAME [ ,PARAMS ]'`.nsubspa NAME [ ,PARAMS ]'Similar to `.space', but selects a subsection NAME within thecurrent section. You may only specify PARAMS when you create asubsection (in the first instance of `.subspa' for this NAME).If specified, the list PARAMS declares attributes of thesubsection, identified by keywords. The keywords recognized are`quad=EXPR' ("quadrant" for this subsection), `align=EXPR'(alignment for beginning of this subsection; a power of two),`access=EXPR' (value for "access rights" field), `sort=EXPR'(sorting order for this subspace in link), `code_only' (subsectioncontains only code), `unloadable' (subsection cannot be loadedinto memory), `comdat' (subsection is comdat), `common'(subsection is common block), `dup_comm' (subsection may haveduplicate names), or `zero' (subsection is all zeros, do not writein object file).`.nsubspa' always creates a new subspace with the given name, evenif one with the same name already exists.`comdat', `common' and `dup_comm' can be used to implement variousflavors of one-only support when using the SOM linker. The SOMlinker only supports specific combinations of these flags. Thedetails are not documented. A brief description is provided here.`comdat' provides a form of linkonce support. It is useful forboth code and data subspaces. A `comdat' subspace has a key symbolmarked by the `is_comdat' flag or `ST_COMDAT'. Only the firstsubspace for any given key is selected. The key symbol becomesuniversal in shared links. This is similar to the behavior of`secondary_def' symbols.`common' provides Fortran named common support. It is only usefulfor data subspaces. Symbols with the flag `is_common' retain thisflag in shared links. Referencing a `is_common' symbol in a sharedlibrary from outside the library doesn't work. Thus, `is_common'symbols must be output whenever they are needed.`common' and `dup_comm' together provide Cobol common support.The subspaces in this case must all be the same length.Otherwise, this support is similar to the Fortran common support.`dup_comm' by itself provides a type of one-only support for code.Only the first `dup_comm' subspace is selected. There is a rathercomplex algorithm to compare subspaces. Code symbols marked withthe `dup_common' flag are hidden. This support was intended for"C++ duplicate inlines".A simplified technique is used to mark the flags of symbols basedon the flags of their subspace. A symbol with the scopeSS_UNIVERSAL and type ST_ENTRY, ST_CODE or ST_DATA is marked withthe corresponding settings of `comdat', `common' and `dup_comm'from the subspace, respectively. This avoids having to introduceadditional directives to mark these symbols. The HP assemblersets `is_common' from `common'. However, it doesn't set the`dup_common' from `dup_comm'. It doesn't have `comdat' support.`.version "STR"'Write STR as version identifier in object code.File: as.info, Node: HPPA Opcodes, Prev: HPPA Directives, Up: HPPA-Dependent9.11.6 Opcodes--------------For detailed information on the HPPA machine instruction set, see`PA-RISC Architecture and Instruction Set Reference Manual' (HP09740-90039).File: as.info, Node: ESA/390-Dependent, Next: i386-Dependent, Prev: HPPA-Dependent, Up: Machine Dependencies9.12 ESA/390 Dependent Features===============================* Menu:* ESA/390 Notes:: Notes* ESA/390 Options:: Options* ESA/390 Syntax:: Syntax* ESA/390 Floating Point:: Floating Point* ESA/390 Directives:: ESA/390 Machine Directives* ESA/390 Opcodes:: OpcodesFile: as.info, Node: ESA/390 Notes, Next: ESA/390 Options, Up: ESA/390-Dependent9.12.1 Notes------------The ESA/390 `as' port is currently intended to be a back-end for theGNU CC compiler. It is not HLASM compatible, although it does supporta subset of some of the HLASM directives. The only supported binaryfile format is ELF; none of the usual MVS/VM/OE/USS object fileformats, such as ESD or XSD, are supported.When used with the GNU CC compiler, the ESA/390 `as' will producecorrect, fully relocated, functional binaries, and has been used tocompile and execute large projects. However, many aspects should stillbe considered experimental; these include shared library support,dynamically loadable objects, and any relocation other than the 31-bitrelocation.File: as.info, Node: ESA/390 Options, Next: ESA/390 Syntax, Prev: ESA/390 Notes, Up: ESA/390-Dependent9.12.2 Options--------------`as' has no machine-dependent command-line options for the ESA/390.File: as.info, Node: ESA/390 Syntax, Next: ESA/390 Floating Point, Prev: ESA/390 Options, Up: ESA/390-Dependent9.12.3 Syntax-------------The opcode/operand syntax follows the ESA/390 Principles of Operationmanual; assembler directives and general syntax are loosely based on theprevailing AT&T/SVR4/ELF/Solaris style notation. HLASM-style directivesare _not_ supported for the most part, with the exception of thosedescribed herein.A leading dot in front of directives is optional, and the case ofdirectives is ignored; thus for example, .using and USING have the sameeffect.A colon may immediately follow a label definition. This is simplyfor compatibility with how most assembly language programmers writecode.`#' is the line comment character.`;' can be used instead of a newline to separate statements.Since `$' has no special meaning, you may use it in symbol names.Registers can be given the symbolic names r0..r15, fp0, fp2, fp4,fp6. By using thesse symbolic names, `as' can detect simple syntaxerrors. The name rarg or r.arg is a synonym for r11, rtca or r.tca forr12, sp, r.sp, dsa r.dsa for r13, lr or r.lr for r14, rbase or r.basefor r3 and rpgt or r.pgt for r4.`*' is the current location counter. Unlike `.' it is alwaysrelative to the last USING directive. Note that this means thatexpressions cannot use multiplication, as any occurrence of `*' will beinterpreted as a location counter.All labels are relative to the last USING. Thus, branches to a labelalways imply the use of base+displacement.Many of the usual forms of address constants / address literals aresupported. Thus,.using *,r3L r15,=A(some_routine)LM r6,r7,=V(some_longlong_extern)A r1,=F'12'AH r0,=H'42'ME r6,=E'3.1416'MD r6,=D'3.14159265358979'O r6,=XL4'cacad0d0'.ltorgshould all behave as expected: that is, an entry in the literal poolwill be created (or reused if it already exists), and the instructionoperands will be the displacement into the literal pool using thecurrent base register (as last declared with the `.using' directive).File: as.info, Node: ESA/390 Floating Point, Next: ESA/390 Directives, Prev: ESA/390 Syntax, Up: ESA/390-Dependent9.12.4 Floating Point---------------------The assembler generates only IEEE floating-point numbers. The olderfloating point formats are not supported.File: as.info, Node: ESA/390 Directives, Next: ESA/390 Opcodes, Prev: ESA/390 Floating Point, Up: ESA/390-Dependent9.12.5 ESA/390 Assembler Directives-----------------------------------`as' for the ESA/390 supports all of the standard ELF/SVR4 assemblerdirectives that are documented in the main part of this documentation.Several additional directives are supported in order to implement theESA/390 addressing model. The most important of these are `.using' and`.ltorg'These are the additional directives in `as' for the ESA/390:`.dc'A small subset of the usual DC directive is supported.`.drop REGNO'Stop using REGNO as the base register. The REGNO must have beenpreviously declared with a `.using' directive in the same sectionas the current section.`.ebcdic STRING'Emit the EBCDIC equivalent of the indicated string. The emittedstring will be null terminated. Note that the directives`.string' etc. emit ascii strings by default.`EQU'The standard HLASM-style EQU directive is not supported; however,the standard `as' directive .equ can be used to the same effect.`.ltorg'Dump the literal pool accumulated so far; begin a new literal pool.The literal pool will be written in the current section; in orderto generate correct assembly, a `.using' must have been previouslyspecified in the same section.`.using EXPR,REGNO'Use REGNO as the base register for all subsequent RX, RS, and SSform instructions. The EXPR will be evaluated to obtain the baseaddress; usually, EXPR will merely be `*'.This assembler allows two `.using' directives to be simultaneouslyoutstanding, one in the `.text' section, and one in another section(typically, the `.data' section). This feature allows dynamicallyloaded objects to be implemented in a relatively straightforwardway. A `.using' directive must always be specified in the `.text'section; this will specify the base register that will be used forbranches in the `.text' section. A second `.using' may bespecified in another section; this will specify the base registerthat is used for non-label address literals. When a second`.using' is specified, then the subsequent `.ltorg' must be put inthe same section; otherwise an error will result.Thus, for example, the following code uses `r3' to address branchtargets and `r4' to address the literal pool, which has beenwritten to the `.data' section. The is, the constants`=A(some_routine)', `=H'42'' and `=E'3.1416'' will all appear inthe `.data' section..data.using LITPOOL,r4.textBASR r3,0.using *,r3B START.long LITPOOLSTART:L r4,4(,r3)L r15,=A(some_routine)LTR r15,r15BNE LABELAH r0,=H'42'LABEL:ME r6,=E'3.1416'.dataLITPOOL:.ltorgNote that this dual-`.using' directive semantics extends and isnot compatible with HLASM semantics. Note that this assemblerdirective does not support the full range of HLASM semantics.File: as.info, Node: ESA/390 Opcodes, Prev: ESA/390 Directives, Up: ESA/390-Dependent9.12.6 Opcodes--------------For detailed information on the ESA/390 machine instruction set, see`ESA/390 Principles of Operation' (IBM Publication Number DZ9AR004).File: as.info, Node: i386-Dependent, Next: i860-Dependent, Prev: ESA/390-Dependent, Up: Machine Dependencies9.13 80386 Dependent Features=============================The i386 version `as' supports both the original Intel 386architecture in both 16 and 32-bit mode as well as AMD x86-64architecture extending the Intel architecture to 64-bits.* Menu:* i386-Options:: Options* i386-Directives:: X86 specific directives* i386-Syntax:: AT&T Syntax versus Intel Syntax* i386-Mnemonics:: Instruction Naming* i386-Regs:: Register Naming* i386-Prefixes:: Instruction Prefixes* i386-Memory:: Memory References* i386-Jumps:: Handling of Jump Instructions* i386-Float:: Floating Point* i386-SIMD:: Intel's MMX and AMD's 3DNow! SIMD Operations* i386-16bit:: Writing 16-bit Code* i386-Arch:: Specifying an x86 CPU architecture* i386-Bugs:: AT&T Syntax bugs* i386-Notes:: NotesFile: as.info, Node: i386-Options, Next: i386-Directives, Up: i386-Dependent9.13.1 Options--------------The i386 version of `as' has a few machine dependent options:`--32 | --64'Select the word size, either 32 bits or 64 bits. Selecting 32-bitimplies Intel i386 architecture, while 64-bit implies AMD x86-64architecture.These options are only available with the ELF object file format,and require that the necessary BFD support has been included (on a32-bit platform you have to add -enable-64-bit-bfd to configureenable 64-bit usage and use x86-64 as target platform).`-n'By default, x86 GAS replaces multiple nop instructions used foralignment within code sections with multi-byte nop instructionssuch as leal 0(%esi,1),%esi. This switch disables theoptimization.`--divide'On SVR4-derived platforms, the character `/' is treated as acomment character, which means that it cannot be used inexpressions. The `--divide' option turns `/' into a normalcharacter. This does not disable `/' at the beginning of a linestarting a comment, or affect using `#' for starting a comment.`-march=CPU[+EXTENSION...]'This option specifies the target processor. The assembler willissue an error message if an attempt is made to assemble aninstruction which will not execute on the target processor. Thefollowing processor names are recognized: `i8086', `i186', `i286',`i386', `i486', `i586', `i686', `pentium', `pentiumpro',`pentiumii', `pentiumiii', `pentium4', `prescott', `nocona',`core', `core2', `k6', `k6_2', `athlon', `opteron', `k8',`amdfam10', `generic32' and `generic64'.In addition to the basic instruction set, the assembler can betold to accept various extension mnemonics. For example,`-march=i686+sse4+vmx' extends I686 with SSE4 and VMX. Thefollowing extensions are currently supported: `mmx', `sse', `sse2',`sse3', `ssse3', `sse4.1', `sse4.2', `sse4', `avx', `vmx', `smx',`xsave', `aes', `pclmul', `fma', `movbe', `ept', `3dnow', `3dnowa',`sse4a', `sse5', `svme', `abm' and `padlock'.When the `.arch' directive is used with `-march', the `.arch'directive will take precedent.`-mtune=CPU'This option specifies a processor to optimize for. When used inconjunction with the `-march' option, only instructions of theprocessor specified by the `-march' option will be generated.Valid CPU values are identical to the processor list of`-march=CPU'.`-msse2avx'This option specifies that the assembler should encode SSEinstructions with VEX prefix.`-msse-check=NONE'`-msse-check=WARNING'`-msse-check=ERROR'These options control if the assembler should check SSEintructions. `-msse-check=NONE' will make the assembler not tocheck SSE instructions, which is the default.`-msse-check=WARNING' will make the assembler issue a warning forany SSE intruction. `-msse-check=ERROR' will make the assemblerissue an error for any SSE intruction.`-mmnemonic=ATT'`-mmnemonic=INTEL'This option specifies instruction mnemonic for matchinginstructions. The `.att_mnemonic' and `.intel_mnemonic'directives will take precedent.`-msyntax=ATT'`-msyntax=INTEL'This option specifies instruction syntax when processinginstructions. The `.att_syntax' and `.intel_syntax' directiveswill take precedent.`-mnaked-reg'This opetion specifies that registers don't require a `%' prefix.The `.att_syntax' and `.intel_syntax' directives will takeprecedent.File: as.info, Node: i386-Directives, Next: i386-Syntax, Prev: i386-Options, Up: i386-Dependent9.13.2 x86 specific Directives------------------------------`.lcomm SYMBOL , LENGTH[, ALIGNMENT]'Reserve LENGTH (an absolute expression) bytes for a local commondenoted by SYMBOL. The section and value of SYMBOL are those ofthe new local common. The addresses are allocated in the bsssection, so that at run-time the bytes start off zeroed. SinceSYMBOL is not declared global, it is normally not visible to `ld'.The optional third parameter, ALIGNMENT, specifies the desiredalignment of the symbol in the bss section.This directive is only available for COFF based x86 targets.File: as.info, Node: i386-Syntax, Next: i386-Mnemonics, Prev: i386-Directives, Up: i386-Dependent9.13.3 AT&T Syntax versus Intel Syntax--------------------------------------`as' now supports assembly using Intel assembler syntax.`.intel_syntax' selects Intel mode, and `.att_syntax' switches back tothe usual AT&T mode for compatibility with the output of `gcc'. Eitherof these directives may have an optional argument, `prefix', or`noprefix' specifying whether registers require a `%' prefix. AT&TSystem V/386 assembler syntax is quite different from Intel syntax. Wemention these differences because almost all 80386 documents use Intelsyntax. Notable differences between the two syntaxes are:* AT&T immediate operands are preceded by `$'; Intel immediateoperands are undelimited (Intel `push 4' is AT&T `pushl $4').AT&T register operands are preceded by `%'; Intel register operandsare undelimited. AT&T absolute (as opposed to PC relative)jump/call operands are prefixed by `*'; they are undelimited inIntel syntax.* AT&T and Intel syntax use the opposite order for source anddestination operands. Intel `add eax, 4' is `addl $4, %eax'. The`source, dest' convention is maintained for compatibility withprevious Unix assemblers. Note that `bound', `invlpga', andinstructions with 2 immediate operands, such as the `enter'instruction, do _not_ have reversed order. *Note i386-Bugs::.* In AT&T syntax the size of memory operands is determined from thelast character of the instruction mnemonic. Mnemonic suffixes of`b', `w', `l' and `q' specify byte (8-bit), word (16-bit), long(32-bit) and quadruple word (64-bit) memory references. Intelsyntax accomplishes this by prefixing memory operands (_not_ theinstruction mnemonics) with `byte ptr', `word ptr', `dword ptr'and `qword ptr'. Thus, Intel `mov al, byte ptr FOO' is `movb FOO,%al' in AT&T syntax.* Immediate form long jumps and calls are `lcall/ljmp $SECTION,$OFFSET' in AT&T syntax; the Intel syntax is `call/jmp farSECTION:OFFSET'. Also, the far return instruction is `lret$STACK-ADJUST' in AT&T syntax; Intel syntax is `ret farSTACK-ADJUST'.* The AT&T assembler does not provide support for multiple sectionprograms. Unix style systems expect all programs to be singlesections.File: as.info, Node: i386-Mnemonics, Next: i386-Regs, Prev: i386-Syntax, Up: i386-Dependent9.13.4 Instruction Naming-------------------------Instruction mnemonics are suffixed with one character modifiers whichspecify the size of operands. The letters `b', `w', `l' and `q'specify byte, word, long and quadruple word operands. If no suffix isspecified by an instruction then `as' tries to fill in the missingsuffix based on the destination register operand (the last one byconvention). Thus, `mov %ax, %bx' is equivalent to `movw %ax, %bx';also, `mov $1, %bx' is equivalent to `movw $1, bx'. Note that this isincompatible with the AT&T Unix assembler which assumes that a missingmnemonic suffix implies long operand size. (This incompatibility doesnot affect compiler output since compilers always explicitly specifythe mnemonic suffix.)Almost all instructions have the same names in AT&T and Intel format.There are a few exceptions. The sign extend and zero extendinstructions need two sizes to specify them. They need a size tosign/zero extend _from_ and a size to zero extend _to_. This isaccomplished by using two instruction mnemonic suffixes in AT&T syntax.Base names for sign extend and zero extend are `movs...' and `movz...'in AT&T syntax (`movsx' and `movzx' in Intel syntax). The instructionmnemonic suffixes are tacked on to this base name, the _from_ suffixbefore the _to_ suffix. Thus, `movsbl %al, %edx' is AT&T syntax for"move sign extend _from_ %al _to_ %edx." Possible suffixes, thus, are`bl' (from byte to long), `bw' (from byte to word), `wl' (from word tolong), `bq' (from byte to quadruple word), `wq' (from word to quadrupleword), and `lq' (from long to quadruple word).The Intel-syntax conversion instructions* `cbw' -- sign-extend byte in `%al' to word in `%ax',* `cwde' -- sign-extend word in `%ax' to long in `%eax',* `cwd' -- sign-extend word in `%ax' to long in `%dx:%ax',* `cdq' -- sign-extend dword in `%eax' to quad in `%edx:%eax',* `cdqe' -- sign-extend dword in `%eax' to quad in `%rax' (x86-64only),* `cqo' -- sign-extend quad in `%rax' to octuple in `%rdx:%rax'(x86-64 only),are called `cbtw', `cwtl', `cwtd', `cltd', `cltq', and `cqto' in AT&Tnaming. `as' accepts either naming for these instructions.Far call/jump instructions are `lcall' and `ljmp' in AT&T syntax,but are `call far' and `jump far' in Intel convention.9.13.5 AT&T Mnemonic versus Intel Mnemonic------------------------------------------`as' supports assembly using Intel mnemonic. `.intel_mnemonic' selectsIntel mnemonic with Intel syntax, and `.att_mnemonic' switches back tothe usual AT&T mnemonic with AT&T syntax for compatibility with theoutput of `gcc'. Several x87 instructions, `fadd', `fdiv', `fdivp',`fdivr', `fdivrp', `fmul', `fsub', `fsubp', `fsubr' and `fsubrp', areimplemented in AT&T System V/386 assembler with different mnemonicsfrom those in Intel IA32 specification. `gcc' generates thoseinstructions with AT&T mnemonic.File: as.info, Node: i386-Regs, Next: i386-Prefixes, Prev: i386-Mnemonics, Up: i386-Dependent9.13.6 Register Naming----------------------Register operands are always prefixed with `%'. The 80386 registersconsist of* the 8 32-bit registers `%eax' (the accumulator), `%ebx', `%ecx',`%edx', `%edi', `%esi', `%ebp' (the frame pointer), and `%esp'(the stack pointer).* the 8 16-bit low-ends of these: `%ax', `%bx', `%cx', `%dx', `%di',`%si', `%bp', and `%sp'.* the 8 8-bit registers: `%ah', `%al', `%bh', `%bl', `%ch', `%cl',`%dh', and `%dl' (These are the high-bytes and low-bytes of `%ax',`%bx', `%cx', and `%dx')* the 6 section registers `%cs' (code section), `%ds' (datasection), `%ss' (stack section), `%es', `%fs', and `%gs'.* the 3 processor control registers `%cr0', `%cr2', and `%cr3'.* the 6 debug registers `%db0', `%db1', `%db2', `%db3', `%db6', and`%db7'.* the 2 test registers `%tr6' and `%tr7'.* the 8 floating point register stack `%st' or equivalently`%st(0)', `%st(1)', `%st(2)', `%st(3)', `%st(4)', `%st(5)',`%st(6)', and `%st(7)'. These registers are overloaded by 8 MMXregisters `%mm0', `%mm1', `%mm2', `%mm3', `%mm4', `%mm5', `%mm6'and `%mm7'.* the 8 SSE registers registers `%xmm0', `%xmm1', `%xmm2', `%xmm3',`%xmm4', `%xmm5', `%xmm6' and `%xmm7'.The AMD x86-64 architecture extends the register set by:* enhancing the 8 32-bit registers to 64-bit: `%rax' (theaccumulator), `%rbx', `%rcx', `%rdx', `%rdi', `%rsi', `%rbp' (theframe pointer), `%rsp' (the stack pointer)* the 8 extended registers `%r8'-`%r15'.* the 8 32-bit low ends of the extended registers: `%r8d'-`%r15d'* the 8 16-bit low ends of the extended registers: `%r8w'-`%r15w'* the 8 8-bit low ends of the extended registers: `%r8b'-`%r15b'* the 4 8-bit registers: `%sil', `%dil', `%bpl', `%spl'.* the 8 debug registers: `%db8'-`%db15'.* the 8 SSE registers: `%xmm8'-`%xmm15'.File: as.info, Node: i386-Prefixes, Next: i386-Memory, Prev: i386-Regs, Up: i386-Dependent9.13.7 Instruction Prefixes---------------------------Instruction prefixes are used to modify the following instruction. Theyare used to repeat string instructions, to provide section overrides, toperform bus lock operations, and to change operand and address sizes.(Most instructions that normally operate on 32-bit operands will use16-bit operands if the instruction has an "operand size" prefix.)Instruction prefixes are best written on the same line as theinstruction they act upon. For example, the `scas' (scan string)instruction is repeated with:repne scas %es:(%edi),%alYou may also place prefixes on the lines immediately preceding theinstruction, but this circumvents checks that `as' does with prefixes,and will not work with all prefixes.Here is a list of instruction prefixes:* Section override prefixes `cs', `ds', `ss', `es', `fs', `gs'.These are automatically added by specifying using theSECTION:MEMORY-OPERAND form for memory references.* Operand/Address size prefixes `data16' and `addr16' change 32-bitoperands/addresses into 16-bit operands/addresses, while `data32'and `addr32' change 16-bit ones (in a `.code16' section) into32-bit operands/addresses. These prefixes _must_ appear on thesame line of code as the instruction they modify. For example, ina 16-bit `.code16' section, you might write:addr32 jmpl *(%ebx)* The bus lock prefix `lock' inhibits interrupts during execution ofthe instruction it precedes. (This is only valid with certaininstructions; see a 80386 manual for details).* The wait for coprocessor prefix `wait' waits for the coprocessor tocomplete the current instruction. This should never be needed forthe 80386/80387 combination.* The `rep', `repe', and `repne' prefixes are added to stringinstructions to make them repeat `%ecx' times (`%cx' times if thecurrent address size is 16-bits).* The `rex' family of prefixes is used by x86-64 to encodeextensions to i386 instruction set. The `rex' prefix has fourbits -- an operand size overwrite (`64') used to change operandsize from 32-bit to 64-bit and X, Y and Z extensions bits used toextend the register set.You may write the `rex' prefixes directly. The `rex64xyz'instruction emits `rex' prefix with all the bits set. By omittingthe `64', `x', `y' or `z' you may write other prefixes as well.Normally, there is no need to write the prefixes explicitly, sincegas will automatically generate them based on the instructionoperands.File: as.info, Node: i386-Memory, Next: i386-Jumps, Prev: i386-Prefixes, Up: i386-Dependent9.13.8 Memory References------------------------An Intel syntax indirect memory reference of the formSECTION:[BASE + INDEX*SCALE + DISP]is translated into the AT&T syntaxSECTION:DISP(BASE, INDEX, SCALE)where BASE and INDEX are the optional 32-bit base and index registers,DISP is the optional displacement, and SCALE, taking the values 1, 2,4, and 8, multiplies INDEX to calculate the address of the operand. Ifno SCALE is specified, SCALE is taken to be 1. SECTION specifies theoptional section register for the memory operand, and may override thedefault section register (see a 80386 manual for section registerdefaults). Note that section overrides in AT&T syntax _must_ bepreceded by a `%'. If you specify a section override which coincideswith the default section register, `as' does _not_ output any sectionregister override prefixes to assemble the given instruction. Thus,section overrides can be specified to emphasize which section registeris used for a given memory operand.Here are some examples of Intel and AT&T style memory references:AT&T: `-4(%ebp)', Intel: `[ebp - 4]'BASE is `%ebp'; DISP is `-4'. SECTION is missing, and the defaultsection is used (`%ss' for addressing with `%ebp' as the baseregister). INDEX, SCALE are both missing.AT&T: `foo(,%eax,4)', Intel: `[foo + eax*4]'INDEX is `%eax' (scaled by a SCALE 4); DISP is `foo'. All otherfields are missing. The section register here defaults to `%ds'.AT&T: `foo(,1)'; Intel `[foo]'This uses the value pointed to by `foo' as a memory operand. Notethat BASE and INDEX are both missing, but there is only _one_ `,'.This is a syntactic exception.AT&T: `%gs:foo'; Intel `gs:foo'This selects the contents of the variable `foo' with sectionregister SECTION being `%gs'.Absolute (as opposed to PC relative) call and jump operands must beprefixed with `*'. If no `*' is specified, `as' always chooses PCrelative addressing for jump/call labels.Any instruction that has a memory operand, but no register operand,_must_ specify its size (byte, word, long, or quadruple) with aninstruction mnemonic suffix (`b', `w', `l' or `q', respectively).The x86-64 architecture adds an RIP (instruction pointer relative)addressing. This addressing mode is specified by using `rip' as a baseregister. Only constant offsets are valid. For example:AT&T: `1234(%rip)', Intel: `[rip + 1234]'Points to the address 1234 bytes past the end of the currentinstruction.AT&T: `symbol(%rip)', Intel: `[rip + symbol]'Points to the `symbol' in RIP relative way, this is shorter thanthe default absolute addressing.Other addressing modes remain unchanged in x86-64 architecture,except registers used are 64-bit instead of 32-bit.File: as.info, Node: i386-Jumps, Next: i386-Float, Prev: i386-Memory, Up: i386-Dependent9.13.9 Handling of Jump Instructions------------------------------------Jump instructions are always optimized to use the smallest possibledisplacements. This is accomplished by using byte (8-bit) displacementjumps whenever the target is sufficiently close. If a byte displacementis insufficient a long displacement is used. We do not support word(16-bit) displacement jumps in 32-bit mode (i.e. prefixing the jumpinstruction with the `data16' instruction prefix), since the 80386insists upon masking `%eip' to 16 bits after the word displacement isadded. (See also *note i386-Arch::)Note that the `jcxz', `jecxz', `loop', `loopz', `loope', `loopnz'and `loopne' instructions only come in byte displacements, so that ifyou use these instructions (`gcc' does not use them) you may get anerror message (and incorrect code). The AT&T 80386 assembler tries toget around this problem by expanding `jcxz foo' tojcxz cx_zerojmp cx_nonzerocx_zero: jmp foocx_nonzero:File: as.info, Node: i386-Float, Next: i386-SIMD, Prev: i386-Jumps, Up: i386-Dependent9.13.10 Floating Point----------------------All 80387 floating point types except packed BCD are supported. (BCDsupport may be added without much difficulty). These data types are16-, 32-, and 64- bit integers, and single (32-bit), double (64-bit),and extended (80-bit) precision floating point. Each supported typehas an instruction mnemonic suffix and a constructor associated withit. Instruction mnemonic suffixes specify the operand's data type.Constructors build these data types into memory.* Floating point constructors are `.float' or `.single', `.double',and `.tfloat' for 32-, 64-, and 80-bit formats. These correspondto instruction mnemonic suffixes `s', `l', and `t'. `t' stands for80-bit (ten byte) real. The 80387 only supports this format viathe `fldt' (load 80-bit real to stack top) and `fstpt' (store80-bit real and pop stack) instructions.* Integer constructors are `.word', `.long' or `.int', and `.quad'for the 16-, 32-, and 64-bit integer formats. The correspondinginstruction mnemonic suffixes are `s' (single), `l' (long), and`q' (quad). As with the 80-bit real format, the 64-bit `q' formatis only present in the `fildq' (load quad integer to stack top)and `fistpq' (store quad integer and pop stack) instructions.Register to register operations should not use instruction mnemonicsuffixes. `fstl %st, %st(1)' will give a warning, and be assembled asif you wrote `fst %st, %st(1)', since all register to registeroperations use 80-bit floating point operands. (Contrast this with`fstl %st, mem', which converts `%st' from 80-bit to 64-bit floatingpoint format, then stores the result in the 4 byte location `mem')File: as.info, Node: i386-SIMD, Next: i386-16bit, Prev: i386-Float, Up: i386-Dependent9.13.11 Intel's MMX and AMD's 3DNow! SIMD Operations----------------------------------------------------`as' supports Intel's MMX instruction set (SIMD instructions forinteger data), available on Intel's Pentium MMX processors and PentiumII processors, AMD's K6 and K6-2 processors, Cyrix' M2 processor, andprobably others. It also supports AMD's 3DNow! instruction set (SIMDinstructions for 32-bit floating point data) available on AMD's K6-2processor and possibly others in the future.Currently, `as' does not support Intel's floating point SIMD, Katmai(KNI).The eight 64-bit MMX operands, also used by 3DNow!, are called`%mm0', `%mm1', ... `%mm7'. They contain eight 8-bit integers, four16-bit integers, two 32-bit integers, one 64-bit integer, or two 32-bitfloating point values. The MMX registers cannot be used at the sametime as the floating point stack.See Intel and AMD documentation, keeping in mind that the operandorder in instructions is reversed from the Intel syntax.File: as.info, Node: i386-16bit, Next: i386-Arch, Prev: i386-SIMD, Up: i386-Dependent9.13.12 Writing 16-bit Code---------------------------While `as' normally writes only "pure" 32-bit i386 code or 64-bitx86-64 code depending on the default configuration, it also supportswriting code to run in real mode or in 16-bit protected mode codesegments. To do this, put a `.code16' or `.code16gcc' directive beforethe assembly language instructions to be run in 16-bit mode. You canswitch `as' back to writing normal 32-bit code with the `.code32'directive.`.code16gcc' provides experimental support for generating 16-bitcode from gcc, and differs from `.code16' in that `call', `ret',`enter', `leave', `push', `pop', `pusha', `popa', `pushf', and `popf'instructions default to 32-bit size. This is so that the stack pointeris manipulated in the same way over function calls, allowing access tofunction parameters at the same stack offsets as in 32-bit mode.`.code16gcc' also automatically adds address size prefixes wherenecessary to use the 32-bit addressing modes that gcc generates.The code which `as' generates in 16-bit mode will not necessarilyrun on a 16-bit pre-80386 processor. To write code that runs on such aprocessor, you must refrain from using _any_ 32-bit constructs whichrequire `as' to output address or operand size prefixes.Note that writing 16-bit code instructions by explicitly specifying aprefix or an instruction mnemonic suffix within a 32-bit code sectiongenerates different machine instructions than those generated for a16-bit code segment. In a 32-bit code section, the following codegenerates the machine opcode bytes `66 6a 04', which pushes the value`4' onto the stack, decrementing `%esp' by 2.pushw $4The same code in a 16-bit code section would generate the machineopcode bytes `6a 04' (i.e., without the operand size prefix), which iscorrect since the processor default operand size is assumed to be 16bits in a 16-bit code section.File: as.info, Node: i386-Bugs, Next: i386-Notes, Prev: i386-Arch, Up: i386-Dependent9.13.13 AT&T Syntax bugs------------------------The UnixWare assembler, and probably other AT&T derived ix86 Unixassemblers, generate floating point instructions with reversed sourceand destination registers in certain cases. Unfortunately, gcc andpossibly many other programs use this reversed syntax, so we're stuckwith it.For examplefsub %st,%st(3)results in `%st(3)' being updated to `%st - %st(3)' rather than theexpected `%st(3) - %st'. This happens with all the non-commutativearithmetic floating point operations with two register operands wherethe source register is `%st' and the destination register is `%st(i)'.File: as.info, Node: i386-Arch, Next: i386-Bugs, Prev: i386-16bit, Up: i386-Dependent9.13.14 Specifying CPU Architecture-----------------------------------`as' may be told to assemble for a particular CPU (sub-)architecturewith the `.arch CPU_TYPE' directive. This directive enables a warningwhen gas detects an instruction that is not supported on the CPUspecified. The choices for CPU_TYPE are:`i8086' `i186' `i286' `i386'`i486' `i586' `i686' `pentium'`pentiumpro' `pentiumii' `pentiumiii' `pentium4'`prescott' `nocona' `core' `core2'`k6' `k6_2' `athlon' `k8'`amdfam10'`generic32' `generic64'`.mmx' `.sse' `.sse2' `.sse3'`.ssse3' `.sse4.1' `.sse4.2' `.sse4'`.avx' `.vmx' `.smx' `.xsave'`.aes' `.pclmul' `.fma' `.movbe'`.ept'`.3dnow' `.3dnowa' `.sse4a' `.sse5'`.svme' `.abm'`.padlock'Apart from the warning, there are only two other effects on `as'operation; Firstly, if you specify a CPU other than `i486', then shiftby one instructions such as `sarl $1, %eax' will automatically use atwo byte opcode sequence. The larger three byte opcode sequence isused on the 486 (and when no architecture is specified) because itexecutes faster on the 486. Note that you can explicitly request thetwo byte opcode by writing `sarl %eax'. Secondly, if you specify`i8086', `i186', or `i286', _and_ `.code16' or `.code16gcc' then byteoffset conditional jumps will be promoted when necessary to a twoinstruction sequence consisting of a conditional jump of the oppositesense around an unconditional jump to the target.Following the CPU architecture (but not a sub-architecture, whichare those starting with a dot), you may specify `jumps' or `nojumps' tocontrol automatic promotion of conditional jumps. `jumps' is thedefault, and enables jump promotion; All external jumps will be of thelong variety, and file-local jumps will be promoted as necessary.(*note i386-Jumps::) `nojumps' leaves external conditional jumps asbyte offset jumps, and warns about file-local conditional jumps that`as' promotes. Unconditional jumps are treated as for `jumps'.For example.arch i8086,nojumpsFile: as.info, Node: i386-Notes, Prev: i386-Bugs, Up: i386-Dependent9.13.15 Notes-------------There is some trickery concerning the `mul' and `imul' instructionsthat deserves mention. The 16-, 32-, 64- and 128-bit expandingmultiplies (base opcode `0xf6'; extension 4 for `mul' and 5 for `imul')can be output only in the one operand form. Thus, `imul %ebx, %eax'does _not_ select the expanding multiply; the expanding multiply wouldclobber the `%edx' register, and this would confuse `gcc' output. Use`imul %ebx' to get the 64-bit product in `%edx:%eax'.We have added a two operand form of `imul' when the first operand isan immediate mode expression and the second operand is a register.This is just a shorthand, so that, multiplying `%eax' by 69, forexample, can be done with `imul $69, %eax' rather than `imul $69, %eax,%eax'.File: as.info, Node: i860-Dependent, Next: i960-Dependent, Prev: i386-Dependent, Up: Machine Dependencies9.14 Intel i860 Dependent Features==================================* Menu:* Notes-i860:: i860 Notes* Options-i860:: i860 Command-line Options* Directives-i860:: i860 Machine Directives* Opcodes for i860:: i860 OpcodesFile: as.info, Node: Notes-i860, Next: Options-i860, Up: i860-Dependent9.14.1 i860 Notes-----------------This is a fairly complete i860 assembler which is compatible with theUNIX System V/860 Release 4 assembler. However, it does not currentlysupport SVR4 PIC (i.e., `@GOT, @GOTOFF, @PLT').Like the SVR4/860 assembler, the output object format is ELF32.Currently, this is the only supported object format. If there issufficient interest, other formats such as COFF may be implemented.Both the Intel and AT&T/SVR4 syntaxes are supported, with the latterbeing the default. One difference is that AT&T syntax requires the '%'prefix on register names while Intel syntax does not. Anotherdifference is in the specification of relocatable expressions. TheIntel syntax is `ha%expression' whereas the SVR4 syntax is`[expression]@ha' (and similarly for the "l" and "h" selectors).File: as.info, Node: Options-i860, Next: Directives-i860, Prev: Notes-i860, Up: i860-Dependent9.14.2 i860 Command-line Options--------------------------------9.14.2.1 SVR4 compatibility options...................................`-V'Print assembler version.`-Qy'Ignored.`-Qn'Ignored.9.14.2.2 Other options......................`-EL'Select little endian output (this is the default).`-EB'Select big endian output. Note that the i860 always readsinstructions as little endian data, so this option only effectsdata and not instructions.`-mwarn-expand'Emit a warning message if any pseudo-instruction expansionsoccurred. For example, a `or' instruction with an immediatelarger than 16-bits will be expanded into two instructions. Thisis a very undesirable feature to rely on, so this flag can helpdetect any code where it happens. One use of it, for instance, hasbeen to find and eliminate any place where `gcc' may emit thesepseudo-instructions.`-mxp'Enable support for the i860XP instructions and control registers.By default, this option is disabled so that only the baseinstruction set (i.e., i860XR) is supported.`-mintel-syntax'The i860 assembler defaults to AT&T/SVR4 syntax. This optionenables the Intel syntax.File: as.info, Node: Directives-i860, Next: Opcodes for i860, Prev: Options-i860, Up: i860-Dependent9.14.3 i860 Machine Directives------------------------------`.dual'Enter dual instruction mode. While this directive is supported, thepreferred way to use dual instruction mode is to explicitly codethe dual bit with the `d.' prefix.`.enddual'Exit dual instruction mode. While this directive is supported, thepreferred way to use dual instruction mode is to explicitly codethe dual bit with the `d.' prefix.`.atmp'Change the temporary register used when expanding pseudooperations. The default register is `r31'.The `.dual', `.enddual', and `.atmp' directives are available onlyin the Intel syntax mode.Both syntaxes allow for the standard `.align' directive. However,the Intel syntax additionally allows keywords for the alignmentparameter: "`.align type'", where `type' is one of `.short', `.long',`.quad', `.single', `.double' representing alignments of 2, 4, 16, 4,and 8, respectively.File: as.info, Node: Opcodes for i860, Prev: Directives-i860, Up: i860-Dependent9.14.4 i860 Opcodes-------------------All of the Intel i860XR and i860XP machine instructions are supported.Please see either _i860 Microprocessor Programmer's Reference Manual_or _i860 Microprocessor Architecture_ for more information.9.14.4.1 Other instruction support (pseudo-instructions)........................................................For compatibility with some other i860 assemblers, a number ofpseudo-instructions are supported. While these are supported, they area very undesirable feature that should be avoided - in particular, whenthey result in an expansion to multiple actual i860 instructions. Beloware the pseudo-instructions that result in expansions.* Load large immediate into general register:The pseudo-instruction `mov imm,%rn' (where the immediate does notfit within a signed 16-bit field) will be expanded into:orh large_imm@h,%r0,%rnor large_imm@l,%rn,%rn* Load/store with relocatable address expression:For example, the pseudo-instruction `ld.b addr_exp(%rx),%rn' willbe expanded into:orh addr_exp@ha,%rx,%r31ld.l addr_exp@l(%r31),%rnThe analogous expansions apply to `ld.x, st.x, fld.x, pfld.x,fst.x', and `pst.x' as well.* Signed large immediate with add/subtract:If any of the arithmetic operations `adds, addu, subs, subu' areused with an immediate larger than 16-bits (signed), then theywill be expanded. For instance, the pseudo-instruction `addslarge_imm,%rx,%rn' expands to:orh large_imm@h,%r0,%r31or large_imm@l,%r31,%r31adds %r31,%rx,%rn* Unsigned large immediate with logical operations:Logical operations (`or, andnot, or, xor') also result inexpansions. The pseudo-instruction `or large_imm,%rx,%rn' resultsin:orh large_imm@h,%rx,%r31or large_imm@l,%r31,%rnSimilarly for the others, except for `and' which expands to:andnot (-1 - large_imm)@h,%rx,%r31andnot (-1 - large_imm)@l,%r31,%rnFile: as.info, Node: i960-Dependent, Next: IA-64-Dependent, Prev: i860-Dependent, Up: Machine Dependencies9.15 Intel 80960 Dependent Features===================================* Menu:* Options-i960:: i960 Command-line Options* Floating Point-i960:: Floating Point* Directives-i960:: i960 Machine Directives* Opcodes for i960:: i960 OpcodesFile: as.info, Node: Options-i960, Next: Floating Point-i960, Up: i960-Dependent9.15.1 i960 Command-line Options--------------------------------`-ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC'Select the 80960 architecture. Instructions or features notsupported by the selected architecture cause fatal errors.`-ACA' is equivalent to `-ACA_A'; `-AKC' is equivalent to `-AMC'.Synonyms are provided for compatibility with other tools.If you do not specify any of these options, `as' generates codefor any instruction or feature that is supported by _some_ versionof the 960 (even if this means mixing architectures!). Inprinciple, `as' attempts to deduce the minimal sufficientprocessor type if none is specified; depending on the object codeformat, the processor type may be recorded in the object file. Ifit is critical that the `as' output match a specific architecture,specify that architecture explicitly.`-b'Add code to collect information about conditional branches taken,for later optimization using branch prediction bits. (Theconditional branch instructions have branch prediction bits in theCA, CB, and CC architectures.) If BR represents a conditionalbranch instruction, the following represents the code generated bythe assembler when `-b' is specified:call INCREMENT ROUTINE.word 0 # pre-counterLabel: BRcall INCREMENT ROUTINE.word 0 # post-counterThe counter following a branch records the number of times thatbranch was _not_ taken; the difference between the two counters isthe number of times the branch _was_ taken.A table of every such `Label' is also generated, so that theexternal postprocessor `gbr960' (supplied by Intel) can locate allthe counters. This table is always labeled `__BRANCH_TABLE__';this is a local symbol to permit collecting statistics for manyseparate object files. The table is word aligned, and begins witha two-word header. The first word, initialized to 0, is used inmaintaining linked lists of branch tables. The second word is acount of the number of entries in the table, which followimmediately: each is a word, pointing to one of the labelsillustrated above.+------------+------------+------------+ ... +------------+| | | | | || *NEXT | COUNT: N | *BRLAB 1 | | *BRLAB N || | | | | |+------------+------------+------------+ ... +------------+__BRANCH_TABLE__ layoutThe first word of the header is used to locate multiple branchtables, since each object file may contain one. Normally the linksare maintained with a call to an initialization routine, placed atthe beginning of each function in the file. The GNU C compilergenerates these calls automatically when you give it a `-b' option.For further details, see the documentation of `gbr960'.`-no-relax'Normally, Compare-and-Branch instructions with targets that requiredisplacements greater than 13 bits (or that have external targets)are replaced with the corresponding compare (or `chkbit') andbranch instructions. You can use the `-no-relax' option tospecify that `as' should generate errors instead, if the targetdisplacement is larger than 13 bits.This option does not affect the Compare-and-Jump instructions; thecode emitted for them is _always_ adjusted when necessary(depending on displacement size), regardless of whether you use`-no-relax'.File: as.info, Node: Floating Point-i960, Next: Directives-i960, Prev: Options-i960, Up: i960-Dependent9.15.2 Floating Point---------------------`as' generates IEEE floating-point numbers for the directives `.float',`.double', `.extended', and `.single'.File: as.info, Node: Directives-i960, Next: Opcodes for i960, Prev: Floating Point-i960, Up: i960-Dependent9.15.3 i960 Machine Directives------------------------------`.bss SYMBOL, LENGTH, ALIGN'Reserve LENGTH bytes in the bss section for a local SYMBOL,aligned to the power of two specified by ALIGN. LENGTH and ALIGNmust be positive absolute expressions. This directive differsfrom `.lcomm' only in that it permits you to specify an alignment.*Note `.lcomm': Lcomm.`.extended FLONUMS'`.extended' expects zero or more flonums, separated by commas; foreach flonum, `.extended' emits an IEEE extended-format (80-bit)floating-point number.`.leafproc CALL-LAB, BAL-LAB'You can use the `.leafproc' directive in conjunction with theoptimized `callj' instruction to enable faster calls of leafprocedures. If a procedure is known to call no other procedures,you may define an entry point that skips procedure prolog code(and that does not depend on system-supplied saved context), anddeclare it as the BAL-LAB using `.leafproc'. If the procedurealso has an entry point that goes through the normal prolog, youcan specify that entry point as CALL-LAB.A `.leafproc' declaration is meant for use in conjunction with theoptimized call instruction `callj'; the directive records the dataneeded later to choose between converting the `callj' into a `bal'or a `call'.CALL-LAB is optional; if only one argument is present, or if thetwo arguments are identical, the single argument is assumed to bethe `bal' entry point.`.sysproc NAME, INDEX'The `.sysproc' directive defines a name for a system procedure.After you define it using `.sysproc', you can use NAME to refer tothe system procedure identified by INDEX when calling procedureswith the optimized call instruction `callj'.Both arguments are required; INDEX must be between 0 and 31(inclusive).File: as.info, Node: Opcodes for i960, Prev: Directives-i960, Up: i960-Dependent9.15.4 i960 Opcodes-------------------All Intel 960 machine instructions are supported; *note i960Command-line Options: Options-i960. for a discussion of selecting theinstruction subset for a particular 960 architecture.Some opcodes are processed beyond simply emitting a singlecorresponding instruction: `callj', and Compare-and-Branch orCompare-and-Jump instructions with target displacements larger than 13bits.* Menu:* callj-i960:: `callj'* Compare-and-branch-i960:: Compare-and-BranchFile: as.info, Node: callj-i960, Next: Compare-and-branch-i960, Up: Opcodes for i9609.15.4.1 `callj'................You can write `callj' to have the assembler or the linker determine themost appropriate form of subroutine call: `call', `bal', or `calls'.If the assembly source contains enough information--a `.leafproc' or`.sysproc' directive defining the operand--then `as' translates the`callj'; if not, it simply emits the `callj', leaving it for the linkerto resolve.File: as.info, Node: Compare-and-branch-i960, Prev: callj-i960, Up: Opcodes for i9609.15.4.2 Compare-and-Branch...........................The 960 architectures provide combined Compare-and-Branch instructionsthat permit you to store the branch target in the lower 13 bits of theinstruction word itself. However, if you specify a branch target farenough away that its address won't fit in 13 bits, the assembler caneither issue an error, or convert your Compare-and-Branch instructioninto separate instructions to do the compare and the branch.Whether `as' gives an error or expands the instruction depends ontwo choices you can make: whether you use the `-no-relax' option, andwhether you use a "Compare and Branch" instruction or a "Compare andJump" instruction. The "Jump" instructions are _always_ expanded ifnecessary; the "Branch" instructions are expanded when necessary_unless_ you specify `-no-relax'--in which case `as' gives an errorinstead.These are the Compare-and-Branch instructions, their "Jump" variants,and the instruction pairs they may expand into:Compare andBranch Jump Expanded to------ ------ ------------bbc chkbit; bnobbs chkbit; bocmpibe cmpije cmpi; becmpibg cmpijg cmpi; bgcmpibge cmpijge cmpi; bgecmpibl cmpijl cmpi; blcmpible cmpijle cmpi; blecmpibno cmpijno cmpi; bnocmpibne cmpijne cmpi; bnecmpibo cmpijo cmpi; bocmpobe cmpoje cmpo; becmpobg cmpojg cmpo; bgcmpobge cmpojge cmpo; bgecmpobl cmpojl cmpo; blcmpoble cmpojle cmpo; blecmpobne cmpojne cmpo; bneFile: as.info, Node: IA-64-Dependent, Next: IP2K-Dependent, Prev: i960-Dependent, Up: Machine Dependencies9.16 IA-64 Dependent Features=============================* Menu:* IA-64 Options:: Options* IA-64 Syntax:: Syntax* IA-64 Opcodes:: OpcodesFile: as.info, Node: IA-64 Options, Next: IA-64 Syntax, Up: IA-64-Dependent9.16.1 Options--------------`-mconstant-gp'This option instructs the assembler to mark the resulting objectfile as using the "constant GP" model. With this model, it isassumed that the entire program uses a single global pointer (GP)value. Note that this option does not in any fashion affect themachine code emitted by the assembler. All it does is turn on theEF_IA_64_CONS_GP flag in the ELF file header.`-mauto-pic'This option instructs the assembler to mark the resulting objectfile as using the "constant GP without function descriptor" datamodel. This model is like the "constant GP" model, except that itadditionally does away with function descriptors. What this meansis that the address of a function refers directly to thefunction's code entry-point. Normally, such an address wouldrefer to a function descriptor, which contains both the codeentry-point and the GP-value needed by the function. Note thatthis option does not in any fashion affect the machine codeemitted by the assembler. All it does is turn on theEF_IA_64_NOFUNCDESC_CONS_GP flag in the ELF file header.`-milp32'`-milp64'`-mlp64'`-mp64'These options select the data model. The assembler defaults to`-mlp64' (LP64 data model).`-mle'`-mbe'These options select the byte order. The `-mle' option selectslittle-endian byte order (default) and `-mbe' selects big-endianbyte order. Note that IA-64 machine code always useslittle-endian byte order.`-mtune=itanium1'`-mtune=itanium2'Tune for a particular IA-64 CPU, ITANIUM1 or ITANIUM2. The defaultis ITANIUM2.`-munwind-check=warning'`-munwind-check=error'These options control what the assembler will do when performingconsistency checks on unwind directives. `-munwind-check=warning'will make the assembler issue a warning when an unwind directivecheck fails. This is the default. `-munwind-check=error' willmake the assembler issue an error when an unwind directive checkfails.`-mhint.b=ok'`-mhint.b=warning'`-mhint.b=error'These options control what the assembler will do when the `hint.b'instruction is used. `-mhint.b=ok' will make the assembler accept`hint.b'. `-mint.b=warning' will make the assembler issue awarning when `hint.b' is used. `-mhint.b=error' will make theassembler treat `hint.b' as an error, which is the default.`-x'`-xexplicit'These options turn on dependency violation checking.`-xauto'This option instructs the assembler to automatically insert stopbits where necessary to remove dependency violations. This is thedefault mode.`-xnone'This option turns off dependency violation checking.`-xdebug'This turns on debug output intended to help tracking down bugs inthe dependency violation checker.`-xdebugn'This is a shortcut for -xnone -xdebug.`-xdebugx'This is a shortcut for -xexplicit -xdebug.File: as.info, Node: IA-64 Syntax, Next: IA-64 Opcodes, Prev: IA-64 Options, Up: IA-64-Dependent9.16.2 Syntax-------------The assembler syntax closely follows the IA-64 Assembly LanguageReference Guide.* Menu:* IA-64-Chars:: Special Characters* IA-64-Regs:: Register Names* IA-64-Bits:: Bit NamesFile: as.info, Node: IA-64-Chars, Next: IA-64-Regs, Up: IA-64 Syntax9.16.2.1 Special Characters...........................`//' is the line comment token.`;' can be used instead of a newline to separate statements.File: as.info, Node: IA-64-Regs, Next: IA-64-Bits, Prev: IA-64-Chars, Up: IA-64 Syntax9.16.2.2 Register Names.......................The 128 integer registers are referred to as `rN'. The 128floating-point registers are referred to as `fN'. The 128 applicationregisters are referred to as `arN'. The 128 control registers arereferred to as `crN'. The 64 one-bit predicate registers are referredto as `pN'. The 8 branch registers are referred to as `bN'. Inaddition, the assembler defines a number of aliases: `gp' (`r1'), `sp'(`r12'), `rp' (`b0'), `ret0' (`r8'), `ret1' (`r9'), `ret2' (`r10'),`ret3' (`r9'), `fargN' (`f8+N'), and `fretN' (`f8+N').For convenience, the assembler also defines aliases for all namedapplication and control registers. For example, `ar.bsp' refers to theregister backing store pointer (`ar17'). Similarly, `cr.eoi' refers tothe end-of-interrupt register (`cr67').File: as.info, Node: IA-64-Bits, Prev: IA-64-Regs, Up: IA-64 Syntax9.16.2.3 IA-64 Processor-Status-Register (PSR) Bit Names........................................................The assembler defines bit masks for each of the bits in the IA-64processor status register. For example, `psr.ic' corresponds to avalue of 0x2000. These masks are primarily intended for use with the`ssm'/`sum' and `rsm'/`rum' instructions, but they can be used anywhereelse where an integer constant is expected.File: as.info, Node: IA-64 Opcodes, Prev: IA-64 Syntax, Up: IA-64-Dependent9.16.3 Opcodes--------------For detailed information on the IA-64 machine instruction set, see theIA-64 Architecture Handbook(http://developer.intel.com/design/itanium/arch_spec.htm).File: as.info, Node: IP2K-Dependent, Next: M32C-Dependent, Prev: IA-64-Dependent, Up: Machine Dependencies9.17 IP2K Dependent Features============================* Menu:* IP2K-Opts:: IP2K OptionsFile: as.info, Node: IP2K-Opts, Up: IP2K-Dependent9.17.1 IP2K Options-------------------The Ubicom IP2K version of `as' has a few machine dependent options:`-mip2022ext'`as' can assemble the extended IP2022 instructions, but it willonly do so if this is specifically allowed via this command lineoption.`-mip2022'This option restores the assembler's default behaviour of notpermitting the extended IP2022 instructions to be assembled.File: as.info, Node: M32C-Dependent, Next: M32R-Dependent, Prev: IP2K-Dependent, Up: Machine Dependencies9.18 M32C Dependent Features============================`as' can assemble code for several different members of the RenesasM32C family. Normally the default is to assemble code for the M16Cmicroprocessor. The `-m32c' option may be used to change the defaultto the M32C microprocessor.* Menu:* M32C-Opts:: M32C Options* M32C-Modifiers:: Symbolic Operand ModifiersFile: as.info, Node: M32C-Opts, Next: M32C-Modifiers, Up: M32C-Dependent9.18.1 M32C Options-------------------The Renesas M32C version of `as' has these machine-dependent options:`-m32c'Assemble M32C instructions.`-m16c'Assemble M16C instructions (default).`-relax'Enable support for link-time relaxations.`-h-tick-hex'Support H'00 style hex constants in addition to 0x00 style.File: as.info, Node: M32C-Modifiers, Prev: M32C-Opts, Up: M32C-Dependent9.18.2 Symbolic Operand Modifiers---------------------------------The assembler supports several modifiers when using symbol addresses inM32C instruction operands. The general syntax is the following:%modifier(symbol)`%dsp8'`%dsp16'These modifiers override the assembler's assumptions about how biga symbol's address is. Normally, when it sees an operand like`sym[a0]' it assumes `sym' may require the widest displacementfield (16 bits for `-m16c', 24 bits for `-m32c'). These modifierstell it to assume the address will fit in an 8 or 16 bit(respectively) unsigned displacement. Note that, of course, if itdoesn't actually fit you will get linker errors. Example:mov.w %dsp8(sym)[a0],r1mov.b #0,%dsp8(sym)[a0]`%hi8'This modifier allows you to load bits 16 through 23 of a 24 bitaddress into an 8 bit register. This is useful with, for example,the M16C `smovf' instruction, which expects a 20 bit address in`r1h' and `a0'. Example:mov.b #%hi8(sym),r1hmov.w #%lo16(sym),a0smovf.b`%lo16'Likewise, this modifier allows you to load bits 0 through 15 of a24 bit address into a 16 bit register.`%hi16'This modifier allows you to load bits 16 through 31 of a 32 bitaddress into a 16 bit register. While the M32C family only has 24bits of address space, it does support addresses in pairs of 16 bitregisters (like `a1a0' for the `lde' instruction). This modifieris for loading the upper half in such cases. Example:mov.w #%hi16(sym),a1mov.w #%lo16(sym),a0...lde.w [a1a0],r1File: as.info, Node: M32R-Dependent, Next: M68K-Dependent, Prev: M32C-Dependent, Up: Machine Dependencies9.19 M32R Dependent Features============================* Menu:* M32R-Opts:: M32R Options* M32R-Directives:: M32R Directives* M32R-Warnings:: M32R WarningsFile: as.info, Node: M32R-Opts, Next: M32R-Directives, Up: M32R-Dependent9.19.1 M32R Options-------------------The Renease M32R version of `as' has a few machine dependent options:`-m32rx'`as' can assemble code for several different members of theRenesas M32R family. Normally the default is to assemble code forthe M32R microprocessor. This option may be used to change thedefault to the M32RX microprocessor, which adds some moreinstructions to the basic M32R instruction set, and someadditional parameters to some of the original instructions.`-m32r2'This option changes the target processor to the the M32R2microprocessor.`-m32r'This option can be used to restore the assembler's defaultbehaviour of assembling for the M32R microprocessor. This can beuseful if the default has been changed by a previous command lineoption.`-little'This option tells the assembler to produce little-endian code anddata. The default is dependent upon how the toolchain wasconfigured.`-EL'This is a synonym for _-little_.`-big'This option tells the assembler to produce big-endian code anddata.`-EB'This is a synonum for _-big_.`-KPIC'This option specifies that the output of the assembler should bemarked as position-independent code (PIC).`-parallel'This option tells the assembler to attempts to combine twosequential instructions into a single, parallel instruction, whereit is legal to do so.`-no-parallel'This option disables a previously enabled _-parallel_ option.`-no-bitinst'This option disables the support for the extended bit-fieldinstructions provided by the M32R2. If this support needs to bere-enabled the _-bitinst_ switch can be used to restore it.`-O'This option tells the assembler to attempt to optimize theinstructions that it produces. This includes filling delay slotsand converting sequential instructions into parallel ones. Thisoption implies _-parallel_.`-warn-explicit-parallel-conflicts'Instructs `as' to produce warning messages when questionableparallel instructions are encountered. This option is enabled bydefault, but `gcc' disables it when it invokes `as' directly.Questionable instructions are those whose behaviour would bedifferent if they were executed sequentially. For example thecode fragment `mv r1, r2 || mv r3, r1' produces a different resultfrom `mv r1, r2 \n mv r3, r1' since the former moves r1 into r3and then r2 into r1, whereas the later moves r2 into r1 and r3.`-Wp'This is a shorter synonym for the_-warn-explicit-parallel-conflicts_ option.`-no-warn-explicit-parallel-conflicts'Instructs `as' not to produce warning messages when questionableparallel instructions are encountered.`-Wnp'This is a shorter synonym for the_-no-warn-explicit-parallel-conflicts_ option.`-ignore-parallel-conflicts'This option tells the assembler's to stop checking parallelinstructions for constraint violations. This ability is providedfor hardware vendors testing chip designs and should not be usedunder normal circumstances.`-no-ignore-parallel-conflicts'This option restores the assembler's default behaviour of checkingparallel instructions to detect constraint violations.`-Ip'This is a shorter synonym for the _-ignore-parallel-conflicts_option.`-nIp'This is a shorter synonym for the _-no-ignore-parallel-conflicts_option.`-warn-unmatched-high'This option tells the assembler to produce a warning message if a`.high' pseudo op is encountered without a matching `.low' pseudoop. The presence of such an unmatched pseudo op usually indicatesa programming error.`-no-warn-unmatched-high'Disables a previously enabled _-warn-unmatched-high_ option.`-Wuh'This is a shorter synonym for the _-warn-unmatched-high_ option.`-Wnuh'This is a shorter synonym for the _-no-warn-unmatched-high_ option.File: as.info, Node: M32R-Directives, Next: M32R-Warnings, Prev: M32R-Opts, Up: M32R-Dependent9.19.2 M32R Directives----------------------The Renease M32R version of `as' has a few architecture specificdirectives:`low EXPRESSION'The `low' directive computes the value of its expression andplaces the lower 16-bits of the result into the immediate-field ofthe instruction. For example:or3 r0, r0, #low(0x12345678) ; compute r0 = r0 | 0x5678add3, r0, r0, #low(fred) ; compute r0 = r0 + low 16-bits of address of fred`high EXPRESSION'The `high' directive computes the value of its expression andplaces the upper 16-bits of the result into the immediate-field ofthe instruction. For example:seth r0, #high(0x12345678) ; compute r0 = 0x12340000seth, r0, #high(fred) ; compute r0 = upper 16-bits of address of fred`shigh EXPRESSION'The `shigh' directive is very similar to the `high' directive. Italso computes the value of its expression and places the upper16-bits of the result into the immediate-field of the instruction.The difference is that `shigh' also checks to see if the lower16-bits could be interpreted as a signed number, and if so itassumes that a borrow will occur from the upper-16 bits. Tocompensate for this the `shigh' directive pre-biases the upper 16bit value by adding one to it. For example:For example:seth r0, #shigh(0x12345678) ; compute r0 = 0x12340000seth r0, #shigh(0x00008000) ; compute r0 = 0x00010000In the second example the lower 16-bits are 0x8000. If these aretreated as a signed value and sign extended to 32-bits then thevalue becomes 0xffff8000. If this value is then added to0x00010000 then the result is 0x00008000.This behaviour is to allow for the different semantics of the`or3' and `add3' instructions. The `or3' instruction treats its16-bit immediate argument as unsigned whereas the `add3' treatsits 16-bit immediate as a signed value. So for example:seth r0, #shigh(0x00008000)add3 r0, r0, #low(0x00008000)Produces the correct result in r0, whereas:seth r0, #shigh(0x00008000)or3 r0, r0, #low(0x00008000)Stores 0xffff8000 into r0.Note - the `shigh' directive does not know where in the assemblysource code the lower 16-bits of the value are going set, so itcannot check to make sure that an `or3' instruction is being usedrather than an `add3' instruction. It is up to the programmer tomake sure that correct directives are used.`.m32r'The directive performs a similar thing as the _-m32r_ command lineoption. It tells the assembler to only accept M32R instructionsfrom now on. An instructions from later M32R architectures arerefused.`.m32rx'The directive performs a similar thing as the _-m32rx_ commandline option. It tells the assembler to start accepting the extrainstructions in the M32RX ISA as well as the ordinary M32R ISA.`.m32r2'The directive performs a similar thing as the _-m32r2_ commandline option. It tells the assembler to start accepting the extrainstructions in the M32R2 ISA as well as the ordinary M32R ISA.`.little'The directive performs a similar thing as the _-little_ commandline option. It tells the assembler to start producinglittle-endian code and data. This option should be used with careas producing mixed-endian binary files is fraught with danger.`.big'The directive performs a similar thing as the _-big_ command lineoption. It tells the assembler to start producing big-endian codeand data. This option should be used with care as producingmixed-endian binary files is fraught with danger.File: as.info, Node: M32R-Warnings, Prev: M32R-Directives, Up: M32R-Dependent9.19.3 M32R Warnings--------------------There are several warning and error messages that can be produced by`as' which are specific to the M32R:`output of 1st instruction is the same as an input to 2nd instruction - is this intentional ?'This message is only produced if warnings for explicit parallelconflicts have been enabled. It indicates that the assembler hasencountered a parallel instruction in which the destinationregister of the left hand instruction is used as an input registerin the right hand instruction. For example in this code fragment`mv r1, r2 || neg r3, r1' register r1 is the destination of themove instruction and the input to the neg instruction.`output of 2nd instruction is the same as an input to 1st instruction - is this intentional ?'This message is only produced if warnings for explicit parallelconflicts have been enabled. It indicates that the assembler hasencountered a parallel instruction in which the destinationregister of the right hand instruction is used as an inputregister in the left hand instruction. For example in this codefragment `mv r1, r2 || neg r2, r3' register r2 is the destinationof the neg instruction and the input to the move instruction.`instruction `...' is for the M32RX only'This message is produced when the assembler encounters aninstruction which is only supported by the M32Rx processor, andthe `-m32rx' command line flag has not been specified to allowassembly of such instructions.`unknown instruction `...''This message is produced when the assembler encounters aninstruction which it does not recognize.`only the NOP instruction can be issued in parallel on the m32r'This message is produced when the assembler encounters a parallelinstruction which does not involve a NOP instruction and the`-m32rx' command line flag has not been specified. Only the M32Rxprocessor is able to execute two instructions in parallel.`instruction `...' cannot be executed in parallel.'This message is produced when the assembler encounters a parallelinstruction which is made up of one or two instructions whichcannot be executed in parallel.`Instructions share the same execution pipeline'This message is produced when the assembler encounters a parallelinstruction whoes components both use the same execution pipeline.`Instructions write to the same destination register.'This message is produced when the assembler encounters a parallelinstruction where both components attempt to modify the sameregister. For example these code fragments will produce thismessage: `mv r1, r2 || neg r1, r3' `jl r0 || mv r14, r1' `st r2,@-r1 || mv r1, r3' `mv r1, r2 || ld r0, @r1+' `cmp r1, r2 || addxr3, r4' (Both write to the condition bit)File: as.info, Node: M68K-Dependent, Next: M68HC11-Dependent, Prev: M32R-Dependent, Up: Machine Dependencies9.20 M680x0 Dependent Features==============================* Menu:* M68K-Opts:: M680x0 Options* M68K-Syntax:: Syntax* M68K-Moto-Syntax:: Motorola Syntax* M68K-Float:: Floating Point* M68K-Directives:: 680x0 Machine Directives* M68K-opcodes:: OpcodesFile: as.info, Node: M68K-Opts, Next: M68K-Syntax, Up: M68K-Dependent9.20.1 M680x0 Options---------------------The Motorola 680x0 version of `as' has a few machine dependent options:`-march=ARCHITECTURE'This option specifies a target architecture. The followingarchitectures are recognized: `68000', `68010', `68020', `68030',`68040', `68060', `cpu32', `isaa', `isaaplus', `isab', `isac' and`cfv4e'.`-mcpu=CPU'This option specifies a target cpu. When used in conjunction withthe `-march' option, the cpu must be within the specifiedarchitecture. Also, the generic features of the architecture areused for instruction generation, rather than those of the specificchip.`-m[no-]68851'`-m[no-]68881'`-m[no-]div'`-m[no-]usp'`-m[no-]float'`-m[no-]mac'`-m[no-]emac'Enable or disable various architecture specific features. If achip or architecture by default supports an option (for instance`-march=isaaplus' includes the `-mdiv' option), explicitlydisabling the option will override the default.`-l'You can use the `-l' option to shorten the size of references toundefined symbols. If you do not use the `-l' option, referencesto undefined symbols are wide enough for a full `long' (32 bits).(Since `as' cannot know where these symbols end up, `as' can onlyallocate space for the linker to fill in later. Since `as' doesnot know how far away these symbols are, it allocates as muchspace as it can.) If you use this option, the references are onlyone word wide (16 bits). This may be useful if you want theobject file to be as small as possible, and you know that therelevant symbols are always less than 17 bits away.`--register-prefix-optional'For some configurations, especially those where the compilernormally does not prepend an underscore to the names of uservariables, the assembler requires a `%' before any use of aregister name. This is intended to let the assembler distinguishbetween C variables and functions named `a0' through `a7', and soon. The `%' is always accepted, but is not required for certainconfigurations, notably `sun3'. The `--register-prefix-optional'option may be used to permit omitting the `%' even forconfigurations for which it is normally required. If this isdone, it will generally be impossible to refer to C variables andfunctions with the same names as register names.`--bitwise-or'Normally the character `|' is treated as a comment character, whichmeans that it can not be used in expressions. The `--bitwise-or'option turns `|' into a normal character. In this mode, you musteither use C style comments, or start comments with a `#' characterat the beginning of a line.`--base-size-default-16 --base-size-default-32'If you use an addressing mode with a base register withoutspecifying the size, `as' will normally use the full 32 bit value.For example, the addressing mode `%a0@(%d0)' is equivalent to`%a0@(%d0:l)'. You may use the `--base-size-default-16' option totell `as' to default to using the 16 bit value. In this case,`%a0@(%d0)' is equivalent to `%a0@(%d0:w)'. You may use the`--base-size-default-32' option to restore the default behaviour.`--disp-size-default-16 --disp-size-default-32'If you use an addressing mode with a displacement, and the valueof the displacement is not known, `as' will normally assume thatthe value is 32 bits. For example, if the symbol `disp' has notbeen defined, `as' will assemble the addressing mode`%a0@(disp,%d0)' as though `disp' is a 32 bit value. You may usethe `--disp-size-default-16' option to tell `as' to instead assumethat the displacement is 16 bits. In this case, `as' willassemble `%a0@(disp,%d0)' as though `disp' is a 16 bit value. Youmay use the `--disp-size-default-32' option to restore the defaultbehaviour.`--pcrel'Always keep branches PC-relative. In the M680x0 architecture allbranches are defined as PC-relative. However, on some processorsthey are limited to word displacements maximum. When `as' needs along branch that is not available, it normally emits an absolutejump instead. This option disables this substitution. When thisoption is given and no long branches are available, only wordbranches will be emitted. An error message will be generated if aword branch cannot reach its target. This option has no effect on68020 and other processors that have long branches. *note BranchImprovement: M68K-Branch.`-m68000'`as' can assemble code for several different members of theMotorola 680x0 family. The default depends upon how `as' wasconfigured when it was built; normally, the default is to assemblecode for the 68020 microprocessor. The following options may beused to change the default. These options control whichinstructions and addressing modes are permitted. The members ofthe 680x0 family are very similar. For detailed information aboutthe differences, see the Motorola manuals.`-m68000'`-m68ec000'`-m68hc000'`-m68hc001'`-m68008'`-m68302'`-m68306'`-m68307'`-m68322'`-m68356'Assemble for the 68000. `-m68008', `-m68302', and so on aresynonyms for `-m68000', since the chips are the same from thepoint of view of the assembler.`-m68010'Assemble for the 68010.`-m68020'`-m68ec020'Assemble for the 68020. This is normally the default.`-m68030'`-m68ec030'Assemble for the 68030.`-m68040'`-m68ec040'Assemble for the 68040.`-m68060'`-m68ec060'Assemble for the 68060.`-mcpu32'`-m68330'`-m68331'`-m68332'`-m68333'`-m68334'`-m68336'`-m68340'`-m68341'`-m68349'`-m68360'Assemble for the CPU32 family of chips.`-m5200'`-m5202'`-m5204'`-m5206'`-m5206e'`-m521x'`-m5249'`-m528x'`-m5307'`-m5407'`-m547x'`-m548x'`-mcfv4'`-mcfv4e'Assemble for the ColdFire family of chips.`-m68881'`-m68882'Assemble 68881 floating point instructions. This is thedefault for the 68020, 68030, and the CPU32. The 68040 and68060 always support floating point instructions.`-mno-68881'Do not assemble 68881 floating point instructions. This isthe default for 68000 and the 68010. The 68040 and 68060always support floating point instructions, even if thisoption is used.`-m68851'Assemble 68851 MMU instructions. This is the default for the68020, 68030, and 68060. The 68040 accepts a somewhatdifferent set of MMU instructions; `-m68851' and `-m68040'should not be used together.`-mno-68851'Do not assemble 68851 MMU instructions. This is the defaultfor the 68000, 68010, and the CPU32. The 68040 accepts asomewhat different set of MMU instructions.File: as.info, Node: M68K-Syntax, Next: M68K-Moto-Syntax, Prev: M68K-Opts, Up: M68K-Dependent9.20.2 Syntax-------------This syntax for the Motorola 680x0 was developed at MIT.The 680x0 version of `as' uses instructions names and syntaxcompatible with the Sun assembler. Intervening periods are ignored;for example, `movl' is equivalent to `mov.l'.In the following table APC stands for any of the address registers(`%a0' through `%a7'), the program counter (`%pc'), the zero-addressrelative to the program counter (`%zpc'), a suppressed address register(`%za0' through `%za7'), or it may be omitted entirely. The use ofSIZE means one of `w' or `l', and it may be omitted, along with theleading colon, unless a scale is also specified. The use of SCALEmeans one of `1', `2', `4', or `8', and it may always be omitted alongwith the leading colon.The following addressing modes are understood:"Immediate"`#NUMBER'"Data Register"`%d0' through `%d7'"Address Register"`%a0' through `%a7'`%a7' is also known as `%sp', i.e., the Stack Pointer. `%a6' isalso known as `%fp', the Frame Pointer."Address Register Indirect"`%a0@' through `%a7@'"Address Register Postincrement"`%a0@+' through `%a7@+'"Address Register Predecrement"`%a0@-' through `%a7@-'"Indirect Plus Offset"`APC@(NUMBER)'"Index"`APC@(NUMBER,REGISTER:SIZE:SCALE)'The NUMBER may be omitted."Postindex"`APC@(NUMBER)@(ONUMBER,REGISTER:SIZE:SCALE)'The ONUMBER or the REGISTER, but not both, may be omitted."Preindex"`APC@(NUMBER,REGISTER:SIZE:SCALE)@(ONUMBER)'The NUMBER may be omitted. Omitting the REGISTER produces thePostindex addressing mode."Absolute"`SYMBOL', or `DIGITS', optionally followed by `:b', `:w', or `:l'.File: as.info, Node: M68K-Moto-Syntax, Next: M68K-Float, Prev: M68K-Syntax, Up: M68K-Dependent9.20.3 Motorola Syntax----------------------The standard Motorola syntax for this chip differs from the syntaxalready discussed (*note Syntax: M68K-Syntax.). `as' can acceptMotorola syntax for operands, even if MIT syntax is used for otheroperands in the same instruction. The two kinds of syntax are fullycompatible.In the following table APC stands for any of the address registers(`%a0' through `%a7'), the program counter (`%pc'), the zero-addressrelative to the program counter (`%zpc'), or a suppressed addressregister (`%za0' through `%za7'). The use of SIZE means one of `w' or`l', and it may always be omitted along with the leading dot. The useof SCALE means one of `1', `2', `4', or `8', and it may always beomitted along with the leading asterisk.The following additional addressing modes are understood:"Address Register Indirect"`(%a0)' through `(%a7)'`%a7' is also known as `%sp', i.e., the Stack Pointer. `%a6' isalso known as `%fp', the Frame Pointer."Address Register Postincrement"`(%a0)+' through `(%a7)+'"Address Register Predecrement"`-(%a0)' through `-(%a7)'"Indirect Plus Offset"`NUMBER(%A0)' through `NUMBER(%A7)', or `NUMBER(%PC)'.The NUMBER may also appear within the parentheses, as in`(NUMBER,%A0)'. When used with the PC, the NUMBER may be omitted(with an address register, omitting the NUMBER produces AddressRegister Indirect mode)."Index"`NUMBER(APC,REGISTER.SIZE*SCALE)'The NUMBER may be omitted, or it may appear within theparentheses. The APC may be omitted. The REGISTER and the APCmay appear in either order. If both APC and REGISTER are addressregisters, and the SIZE and SCALE are omitted, then the firstregister is taken as the base register, and the second as theindex register."Postindex"`([NUMBER,APC],REGISTER.SIZE*SCALE,ONUMBER)'The ONUMBER, or the REGISTER, or both, may be omitted. Either theNUMBER or the APC may be omitted, but not both."Preindex"`([NUMBER,APC,REGISTER.SIZE*SCALE],ONUMBER)'The NUMBER, or the APC, or the REGISTER, or any two of them, maybe omitted. The ONUMBER may be omitted. The REGISTER and the APCmay appear in either order. If both APC and REGISTER are addressregisters, and the SIZE and SCALE are omitted, then the firstregister is taken as the base register, and the second as theindex register.File: as.info, Node: M68K-Float, Next: M68K-Directives, Prev: M68K-Moto-Syntax, Up: M68K-Dependent9.20.4 Floating Point---------------------Packed decimal (P) format floating literals are not supported. Feelfree to add the code!The floating point formats generated by directives are these.`.float'`Single' precision floating point constants.`.double'`Double' precision floating point constants.`.extend'`.ldouble'`Extended' precision (`long double') floating point constants.File: as.info, Node: M68K-Directives, Next: M68K-opcodes, Prev: M68K-Float, Up: M68K-Dependent9.20.5 680x0 Machine Directives-------------------------------In order to be compatible with the Sun assembler the 680x0 assemblerunderstands the following directives.`.data1'This directive is identical to a `.data 1' directive.`.data2'This directive is identical to a `.data 2' directive.`.even'This directive is a special case of the `.align' directive; italigns the output to an even byte boundary.`.skip'This directive is identical to a `.space' directive.`.arch NAME'Select the target architecture and extension features. Validvalues for NAME are the same as for the `-march' command lineoption. This directive cannot be specified after any instructionshave been assembled. If it is given multiple times, or inconjunction with the `-march' option, all uses must be for thesame architecture and extension set.`.cpu NAME'Select the target cpu. Valid valuse for NAME are the same as forthe `-mcpu' command line option. This directive cannot bespecified after any instructions have been assembled. If it isgiven multiple times, or in conjunction with the `-mopt' option,all uses must be for the same cpu.File: as.info, Node: M68K-opcodes, Prev: M68K-Directives, Up: M68K-Dependent9.20.6 Opcodes--------------* Menu:* M68K-Branch:: Branch Improvement* M68K-Chars:: Special CharactersFile: as.info, Node: M68K-Branch, Next: M68K-Chars, Up: M68K-opcodes9.20.6.1 Branch Improvement...........................Certain pseudo opcodes are permitted for branch instructions. Theyexpand to the shortest branch instruction that reach the target.Generally these mnemonics are made by substituting `j' for `b' at thestart of a Motorola mnemonic.The following table summarizes the pseudo-operations. A `*' flagscases that are more fully described after the table:Displacement+------------------------------------------------------------| 68020 68000/10, not PC-relative OKPseudo-Op |BYTE WORD LONG ABSOLUTE LONG JUMP **+------------------------------------------------------------jbsr |bsrs bsrw bsrl jsrjra |bras braw bral jmp* jXX |bXXs bXXw bXXl bNXs;jmp* dbXX | N/A dbXXw dbXX;bras;bral dbXX;bras;jmpfjXX | N/A fbXXw fbXXl N/AXX: conditionNX: negative of condition XX`*'--see full description below`**'--this expansion mode is disallowed by `--pcrel'`jbsr'`jra'These are the simplest jump pseudo-operations; they always map toone particular machine instruction, depending on the displacementto the branch target. This instruction will be a byte or wordbranch is that is sufficient. Otherwise, a long branch will beemitted if available. If no long branches are available and the`--pcrel' option is not given, an absolute long jump will beemitted instead. If no long branches are available, the `--pcrel'option is given, and a word branch cannot reach the target, anerror message is generated.In addition to standard branch operands, `as' allows thesepseudo-operations to have all operands that are allowed for jsrand jmp, substituting these instructions if the operand given isnot valid for a branch instruction.`jXX'Here, `jXX' stands for an entire family of pseudo-operations,where XX is a conditional branch or condition-code test. The fulllist of pseudo-ops in this family is:jhi jls jcc jcs jne jeq jvcjvs jpl jmi jge jlt jgt jleUsually, each of these pseudo-operations expands to a single branchinstruction. However, if a word branch is not sufficient, no longbranches are available, and the `--pcrel' option is not given, `as'issues a longer code fragment in terms of NX, the oppositecondition to XX. For example, under these conditions:jXX foogivesbNXs oofjmp foooof:`dbXX'The full family of pseudo-operations covered here isdbhi dbls dbcc dbcs dbne dbeq dbvcdbvs dbpl dbmi dbge dblt dbgt dbledbf dbra dbtMotorola `dbXX' instructions allow word displacements only. Whena word displacement is sufficient, each of these pseudo-operationsexpands to the corresponding Motorola instruction. When a worddisplacement is not sufficient and long branches are available,when the source reads `dbXX foo', `as' emitsdbXX oo1bras oo2oo1:bral foooo2:If, however, long branches are not available and the `--pcrel'option is not given, `as' emitsdbXX oo1bras oo2oo1:jmp foooo2:`fjXX'This family includesfjne fjeq fjge fjlt fjgt fjle fjffjt fjgl fjgle fjnge fjngl fjngle fjngtfjnle fjnlt fjoge fjogl fjogt fjole fjoltfjor fjseq fjsf fjsne fjst fjueq fjugefjugt fjule fjult fjunEach of these pseudo-operations always expands to a single Motorolacoprocessor branch instruction, word or long. All Motorolacoprocessor branch instructions allow both word and longdisplacements.File: as.info, Node: M68K-Chars, Prev: M68K-Branch, Up: M68K-opcodes9.20.6.2 Special Characters...........................The immediate character is `#' for Sun compatibility. The line-commentcharacter is `|' (unless the `--bitwise-or' option is used). If a `#'appears at the beginning of a line, it is treated as a comment unlessit looks like `# line file', in which case it is treated normally.File: as.info, Node: M68HC11-Dependent, Next: MIPS-Dependent, Prev: M68K-Dependent, Up: Machine Dependencies9.21 M68HC11 and M68HC12 Dependent Features===========================================* Menu:* M68HC11-Opts:: M68HC11 and M68HC12 Options* M68HC11-Syntax:: Syntax* M68HC11-Modifiers:: Symbolic Operand Modifiers* M68HC11-Directives:: Assembler Directives* M68HC11-Float:: Floating Point* M68HC11-opcodes:: OpcodesFile: as.info, Node: M68HC11-Opts, Next: M68HC11-Syntax, Up: M68HC11-Dependent9.21.1 M68HC11 and M68HC12 Options----------------------------------The Motorola 68HC11 and 68HC12 version of `as' have a few machinedependent options.`-m68hc11'This option switches the assembler in the M68HC11 mode. In thismode, the assembler only accepts 68HC11 operands and mnemonics. Itproduces code for the 68HC11.`-m68hc12'This option switches the assembler in the M68HC12 mode. In thismode, the assembler also accepts 68HC12 operands and mnemonics. Itproduces code for the 68HC12. A few 68HC11 instructions arereplaced by some 68HC12 instructions as recommended by Motorolaspecifications.`-m68hcs12'This option switches the assembler in the M68HCS12 mode. Thismode is similar to `-m68hc12' but specifies to assemble for the68HCS12 series. The only difference is on the assembling of the`movb' and `movw' instruction when a PC-relative operand is used.`-mshort'This option controls the ABI and indicates to use a 16-bit integerABI. It has no effect on the assembled instructions. This is thedefault.`-mlong'This option controls the ABI and indicates to use a 32-bit integerABI.`-mshort-double'This option controls the ABI and indicates to use a 32-bit floatABI. This is the default.`-mlong-double'This option controls the ABI and indicates to use a 64-bit floatABI.`--strict-direct-mode'You can use the `--strict-direct-mode' option to disable theautomatic translation of direct page mode addressing into extendedmode when the instruction does not support direct mode. Forexample, the `clr' instruction does not support direct page modeaddressing. When it is used with the direct page mode, `as' willignore it and generate an absolute addressing. This optionprevents `as' from doing this, and the wrong usage of the directpage mode will raise an error.`--short-branches'The `--short-branches' option turns off the translation ofrelative branches into absolute branches when the branch offset isout of range. By default `as' transforms the relative branch(`bsr', `bgt', `bge', `beq', `bne', `ble', `blt', `bhi', `bcc',`bls', `bcs', `bmi', `bvs', `bvs', `bra') into an absolute branchwhen the offset is out of the -128 .. 127 range. In that case,the `bsr' instruction is translated into a `jsr', the `bra'instruction is translated into a `jmp' and the conditionalbranches instructions are inverted and followed by a `jmp'. Thisoption disables these translations and `as' will generate an errorif a relative branch is out of range. This option does not affectthe optimization associated to the `jbra', `jbsr' and `jbXX'pseudo opcodes.`--force-long-branches'The `--force-long-branches' option forces the translation ofrelative branches into absolute branches. This option does notaffect the optimization associated to the `jbra', `jbsr' and`jbXX' pseudo opcodes.`--print-insn-syntax'You can use the `--print-insn-syntax' option to obtain the syntaxdescription of the instruction when an error is detected.`--print-opcodes'The `--print-opcodes' option prints the list of all theinstructions with their syntax. The first item of each linerepresents the instruction name and the rest of the line indicatesthe possible operands for that instruction. The list is printed inalphabetical order. Once the list is printed `as' exits.`--generate-example'The `--generate-example' option is similar to `--print-opcodes'but it generates an example for each instruction instead.File: as.info, Node: M68HC11-Syntax, Next: M68HC11-Modifiers, Prev: M68HC11-Opts, Up: M68HC11-Dependent9.21.2 Syntax-------------In the M68HC11 syntax, the instruction name comes first and it may befollowed by one or several operands (up to three). Operands areseparated by comma (`,'). In the normal mode, `as' will complain if toomany operands are specified for a given instruction. In the MRI mode(turned on with `-M' option), it will treat them as comments. Example:inxlda #23bset 2,x #4brclr *bot #8 fooThe following addressing modes are understood for 68HC11 and 68HC12:"Immediate"`#NUMBER'"Address Register"`NUMBER,X', `NUMBER,Y'The NUMBER may be omitted in which case 0 is assumed."Direct Addressing mode"`*SYMBOL', or `*DIGITS'"Absolute"`SYMBOL', or `DIGITS'The M68HC12 has other more complex addressing modes. All of them aresupported and they are represented below:"Constant Offset Indexed Addressing Mode"`NUMBER,REG'The NUMBER may be omitted in which case 0 is assumed. Theregister can be either `X', `Y', `SP' or `PC'. The assembler willuse the smaller post-byte definition according to the constantvalue (5-bit constant offset, 9-bit constant offset or 16-bitconstant offset). If the constant is not known by the assemblerit will use the 16-bit constant offset post-byte and the valuewill be resolved at link time."Offset Indexed Indirect"`[NUMBER,REG]'The register can be either `X', `Y', `SP' or `PC'."Auto Pre-Increment/Pre-Decrement/Post-Increment/Post-Decrement"`NUMBER,-REG' `NUMBER,+REG' `NUMBER,REG-' `NUMBER,REG+'The number must be in the range `-8'..`+8' and must not be 0. Theregister can be either `X', `Y', `SP' or `PC'."Accumulator Offset"`ACC,REG'The accumulator register can be either `A', `B' or `D'. Theregister can be either `X', `Y', `SP' or `PC'."Accumulator D offset indexed-indirect"`[D,REG]'The register can be either `X', `Y', `SP' or `PC'.For example:ldab 1024,spldd [10,x]orab 3,+xstab -2,y-ldx a,pcsty [d,sp]File: as.info, Node: M68HC11-Modifiers, Next: M68HC11-Directives, Prev: M68HC11-Syntax, Up: M68HC11-Dependent9.21.3 Symbolic Operand Modifiers---------------------------------The assembler supports several modifiers when using symbol addresses in68HC11 and 68HC12 instruction operands. The general syntax is thefollowing:%modifier(symbol)`%addr'This modifier indicates to the assembler and linker to use the16-bit physical address corresponding to the symbol. This isintended to be used on memory window systems to map a symbol inthe memory bank window. If the symbol is in a memory expansionpart, the physical address corresponds to the symbol addresswithin the memory bank window. If the symbol is not in a memoryexpansion part, this is the symbol address (using or not using the%addr modifier has no effect in that case).`%page'This modifier indicates to use the memory page number correspondingto the symbol. If the symbol is in a memory expansion part, itspage number is computed by the linker as a number used to map thepage containing the symbol in the memory bank window. If thesymbol is not in a memory expansion part, the page number is 0.`%hi'This modifier indicates to use the 8-bit high part of the physicaladdress of the symbol.`%lo'This modifier indicates to use the 8-bit low part of the physicaladdress of the symbol.For example a 68HC12 call to a function `foo_example' stored inmemory expansion part could be written as follows:call %addr(foo_example),%page(foo_example)and this is equivalent tocall foo_exampleAnd for 68HC11 it could be written as follows:ldab #%page(foo_example)stab _page_switchjsr %addr(foo_example)File: as.info, Node: M68HC11-Directives, Next: M68HC11-Float, Prev: M68HC11-Modifiers, Up: M68HC11-Dependent9.21.4 Assembler Directives---------------------------The 68HC11 and 68HC12 version of `as' have the following specificassembler directives:`.relax'The relax directive is used by the `GNU Compiler' to emit aspecific relocation to mark a group of instructions for linkerrelaxation. The sequence of instructions within the group must beknown to the linker so that relaxation can be performed.`.mode [mshort|mlong|mshort-double|mlong-double]'This directive specifies the ABI. It overrides the `-mshort',`-mlong', `-mshort-double' and `-mlong-double' options.`.far SYMBOL'This directive marks the symbol as a `far' symbol meaning that ituses a `call/rtc' calling convention as opposed to `jsr/rts'.During a final link, the linker will identify references to the`far' symbol and will verify the proper calling convention.`.interrupt SYMBOL'This directive marks the symbol as an interrupt entry point. Thisinformation is then used by the debugger to correctly unwind theframe across interrupts.`.xrefb SYMBOL'This directive is defined for compatibility with the`Specification for Motorola 8 and 16-Bit Assembly Language InputStandard' and is ignored.File: as.info, Node: M68HC11-Float, Next: M68HC11-opcodes, Prev: M68HC11-Directives, Up: M68HC11-Dependent9.21.5 Floating Point---------------------Packed decimal (P) format floating literals are not supported. Feelfree to add the code!The floating point formats generated by directives are these.`.float'`Single' precision floating point constants.`.double'`Double' precision floating point constants.`.extend'`.ldouble'`Extended' precision (`long double') floating point constants.File: as.info, Node: M68HC11-opcodes, Prev: M68HC11-Float, Up: M68HC11-Dependent9.21.6 Opcodes--------------* Menu:* M68HC11-Branch:: Branch ImprovementFile: as.info, Node: M68HC11-Branch, Up: M68HC11-opcodes9.21.6.1 Branch Improvement...........................Certain pseudo opcodes are permitted for branch instructions. Theyexpand to the shortest branch instruction that reach the target.Generally these mnemonics are made by prepending `j' to the start ofMotorola mnemonic. These pseudo opcodes are not affected by the`--short-branches' or `--force-long-branches' options.The following table summarizes the pseudo-operations.Displacement Width+-------------------------------------------------------------+| Options || --short-branches --force-long-branches |+--------------------------+----------------------------------+Op |BYTE WORD | BYTE WORD |+--------------------------+----------------------------------+bsr | bsr <pc-rel> <error> | jsr <abs> |bra | bra <pc-rel> <error> | jmp <abs> |jbsr | bsr <pc-rel> jsr <abs> | bsr <pc-rel> jsr <abs> |jbra | bra <pc-rel> jmp <abs> | bra <pc-rel> jmp <abs> |bXX | bXX <pc-rel> <error> | bNX +3; jmp <abs> |jbXX | bXX <pc-rel> bNX +3; | bXX <pc-rel> bNX +3; jmp <abs> || jmp <abs> | |+--------------------------+----------------------------------+XX: conditionNX: negative of condition XX`jbsr'`jbra'These are the simplest jump pseudo-operations; they always map toone particular machine instruction, depending on the displacementto the branch target.`jbXX'Here, `jbXX' stands for an entire family of pseudo-operations,where XX is a conditional branch or condition-code test. The fulllist of pseudo-ops in this family is:jbcc jbeq jbge jbgt jbhi jbvs jbpl jblojbcs jbne jblt jble jbls jbvc jbmiFor the cases of non-PC relative displacements and longdisplacements, `as' issues a longer code fragment in terms of NX,the opposite condition to XX. For example, for the non-PCrelative case:jbXX foogivesbNXs oofjmp foooof:File: as.info, Node: MIPS-Dependent, Next: MMIX-Dependent, Prev: M68HC11-Dependent, Up: Machine Dependencies9.22 MIPS Dependent Features============================GNU `as' for MIPS architectures supports several different MIPSprocessors, and MIPS ISA levels I through V, MIPS32, and MIPS64. Forinformation about the MIPS instruction set, see `MIPS RISCArchitecture', by Kane and Heindrich (Prentice-Hall). For an overviewof MIPS assembly conventions, see "Appendix D: Assembly LanguageProgramming" in the same work.* Menu:* MIPS Opts:: Assembler options* MIPS Object:: ECOFF object code* MIPS Stabs:: Directives for debugging information* MIPS ISA:: Directives to override the ISA level* MIPS symbol sizes:: Directives to override the size of symbols* MIPS autoextend:: Directives for extending MIPS 16 bit instructions* MIPS insn:: Directive to mark data as an instruction* MIPS option stack:: Directives to save and restore options* MIPS ASE instruction generation overrides:: Directives to controlgeneration of MIPS ASE instructions* MIPS floating-point:: Directives to override floating-point optionsFile: as.info, Node: MIPS Opts, Next: MIPS Object, Up: MIPS-Dependent9.22.1 Assembler options------------------------The MIPS configurations of GNU `as' support these special options:`-G NUM'This option sets the largest size of an object that can bereferenced implicitly with the `gp' register. It is only acceptedfor targets that use ECOFF format. The default value is 8.`-EB'`-EL'Any MIPS configuration of `as' can select big-endian orlittle-endian output at run time (unlike the other GNU developmenttools, which must be configured for one or the other). Use `-EB'to select big-endian output, and `-EL' for little-endian.`-KPIC'Generate SVR4-style PIC. This option tells the assembler togenerate SVR4-style position-independent macro expansions. Italso tells the assembler to mark the output file as PIC.`-mvxworks-pic'Generate VxWorks PIC. This option tells the assembler to generateVxWorks-style position-independent macro expansions.`-mips1'`-mips2'`-mips3'`-mips4'`-mips5'`-mips32'`-mips32r2'`-mips64'`-mips64r2'Generate code for a particular MIPS Instruction Set Architecturelevel. `-mips1' corresponds to the R2000 and R3000 processors,`-mips2' to the R6000 processor, `-mips3' to the R4000 processor,and `-mips4' to the R8000 and R10000 processors. `-mips5',`-mips32', `-mips32r2', `-mips64', and `-mips64r2' correspond togeneric MIPS V, MIPS32, MIPS32 RELEASE 2, MIPS64, and MIPS64RELEASE 2 ISA processors, respectively. You can also switchinstruction sets during the assembly; see *Note Directives tooverride the ISA level: MIPS ISA.`-mgp32'`-mfp32'Some macros have different expansions for 32-bit and 64-bitregisters. The register sizes are normally inferred from the ISAand ABI, but these flags force a certain group of registers to betreated as 32 bits wide at all times. `-mgp32' controls the sizeof general-purpose registers and `-mfp32' controls the size offloating-point registers.The `.set gp=32' and `.set fp=32' directives allow the size ofregisters to be changed for parts of an object. The default valueis restored by `.set gp=default' and `.set fp=default'.On some MIPS variants there is a 32-bit mode flag; when this flagis set, 64-bit instructions generate a trap. Also, some 32-bitOSes only save the 32-bit registers on a context switch, so it isessential never to use the 64-bit registers.`-mgp64'`-mfp64'Assume that 64-bit registers are available. This is provided inthe interests of symmetry with `-mgp32' and `-mfp32'.The `.set gp=64' and `.set fp=64' directives allow the size ofregisters to be changed for parts of an object. The default valueis restored by `.set gp=default' and `.set fp=default'.`-mips16'`-no-mips16'Generate code for the MIPS 16 processor. This is equivalent toputting `.set mips16' at the start of the assembly file.`-no-mips16' turns off this option.`-msmartmips'`-mno-smartmips'Enables the SmartMIPS extensions to the MIPS32 instruction set,which provides a number of new instructions which target smartcardand cryptographic applications. This is equivalent to putting`.set smartmips' at the start of the assembly file.`-mno-smartmips' turns off this option.`-mips3d'`-no-mips3d'Generate code for the MIPS-3D Application Specific Extension.This tells the assembler to accept MIPS-3D instructions.`-no-mips3d' turns off this option.`-mdmx'`-no-mdmx'Generate code for the MDMX Application Specific Extension. Thistells the assembler to accept MDMX instructions. `-no-mdmx' turnsoff this option.`-mdsp'`-mno-dsp'Generate code for the DSP Release 1 Application Specific Extension.This tells the assembler to accept DSP Release 1 instructions.`-mno-dsp' turns off this option.`-mdspr2'`-mno-dspr2'Generate code for the DSP Release 2 Application Specific Extension.This option implies -mdsp. This tells the assembler to accept DSPRelease 2 instructions. `-mno-dspr2' turns off this option.`-mmt'`-mno-mt'Generate code for the MT Application Specific Extension. Thistells the assembler to accept MT instructions. `-mno-mt' turnsoff this option.`-mfix7000'`-mno-fix7000'Cause nops to be inserted if the read of the destination registerof an mfhi or mflo instruction occurs in the following twoinstructions.`-mfix-vr4120'`-no-mfix-vr4120'Insert nops to work around certain VR4120 errata. This option isintended to be used on GCC-generated code: it is not designed tocatch all problems in hand-written assembler code.`-mfix-vr4130'`-no-mfix-vr4130'Insert nops to work around the VR4130 `mflo'/`mfhi' errata.`-m4010'`-no-m4010'Generate code for the LSI R4010 chip. This tells the assembler toaccept the R4010 specific instructions (`addciu', `ffc', etc.),and to not schedule `nop' instructions around accesses to the `HI'and `LO' registers. `-no-m4010' turns off this option.`-m4650'`-no-m4650'Generate code for the MIPS R4650 chip. This tells the assemblerto accept the `mad' and `madu' instruction, and to not schedule`nop' instructions around accesses to the `HI' and `LO' registers.`-no-m4650' turns off this option.`-m3900'`-no-m3900'`-m4100'`-no-m4100'For each option `-mNNNN', generate code for the MIPS RNNNN chip.This tells the assembler to accept instructions specific to thatchip, and to schedule for that chip's hazards.`-march=CPU'Generate code for a particular MIPS cpu. It is exactly equivalentto `-mCPU', except that there are more value of CPU understood.Valid CPU value are:2000, 3000, 3900, 4000, 4010, 4100, 4111, vr4120, vr4130,vr4181, 4300, 4400, 4600, 4650, 5000, rm5200, rm5230, rm5231,rm5261, rm5721, vr5400, vr5500, 6000, rm7000, 8000, rm9000,10000, 12000, 4kc, 4km, 4kp, 4ksc, 4kec, 4kem, 4kep, 4ksd,m4k, m4kp, 24kc, 24kf2_1, 24kf, 24kf1_1, 24kec, 24kef2_1,24kef, 24kef1_1, 34kc, 34kf2_1, 34kf, 34kf1_1, 74kc, 74kf2_1,74kf, 74kf1_1, 74kf3_2, 5kc, 5kf, 20kc, 25kf, sb1, sb1a,loongson2e, loongson2f, octeonFor compatibility reasons, `Nx' and `Bfx' are accepted as synonymsfor `Nf1_1'. These values are deprecated.`-mtune=CPU'Schedule and tune for a particular MIPS cpu. Valid CPU values areidentical to `-march=CPU'.`-mabi=ABI'Record which ABI the source code uses. The recognized argumentsare: `32', `n32', `o64', `64' and `eabi'.`-msym32'`-mno-sym32'Equivalent to adding `.set sym32' or `.set nosym32' to thebeginning of the assembler input. *Note MIPS symbol sizes::.`-nocpp'This option is ignored. It is accepted for command-linecompatibility with other assemblers, which use it to turn off Cstyle preprocessing. With GNU `as', there is no need for`-nocpp', because the GNU assembler itself never runs the Cpreprocessor.`-msoft-float'`-mhard-float'Disable or enable floating-point instructions. Note that bydefault floating-point instructions are always allowed even withCPU targets that don't have support for these instructions.`-msingle-float'`-mdouble-float'Disable or enable double-precision floating-point operations. Notethat by default double-precision floating-point operations arealways allowed even with CPU targets that don't have support forthese operations.`--construct-floats'`--no-construct-floats'The `--no-construct-floats' option disables the construction ofdouble width floating point constants by loading the two halves ofthe value into the two single width floating point registers thatmake up the double width register. This feature is useful if theprocessor support the FR bit in its status register, and this bitis known (by the programmer) to be set. This bit prevents thealiasing of the double width register by the single widthregisters.By default `--construct-floats' is selected, allowing constructionof these floating point constants.`--trap'`--no-break'`as' automatically macro expands certain division andmultiplication instructions to check for overflow and division byzero. This option causes `as' to generate code to take a trapexception rather than a break exception when an error is detected.The trap instructions are only supported at Instruction SetArchitecture level 2 and higher.`--break'`--no-trap'Generate code to take a break exception rather than a trapexception when an error is detected. This is the default.`-mpdr'`-mno-pdr'Control generation of `.pdr' sections. Off by default on IRIX, onelsewhere.`-mshared'`-mno-shared'When generating code using the Unix calling conventions (selectedby `-KPIC' or `-mcall_shared'), gas will normally generate codewhich can go into a shared library. The `-mno-shared' optiontells gas to generate code which uses the calling convention, butcan not go into a shared library. The resulting code is slightlymore efficient. This option only affects the handling of the`.cpload' and `.cpsetup' pseudo-ops.File: as.info, Node: MIPS Object, Next: MIPS Stabs, Prev: MIPS Opts, Up: MIPS-Dependent9.22.2 MIPS ECOFF object code-----------------------------Assembling for a MIPS ECOFF target supports some additional sectionsbesides the usual `.text', `.data' and `.bss'. The additional sectionsare `.rdata', used for read-only data, `.sdata', used for small data,and `.sbss', used for small common objects.When assembling for ECOFF, the assembler uses the `$gp' (`$28')register to form the address of a "small object". Any object in the`.sdata' or `.sbss' sections is considered "small" in this sense. Forexternal objects, or for objects in the `.bss' section, you can use the`gcc' `-G' option to control the size of objects addressed via `$gp';the default value is 8, meaning that a reference to any object eightbytes or smaller uses `$gp'. Passing `-G 0' to `as' prevents it fromusing the `$gp' register on the basis of object size (but the assembleruses `$gp' for objects in `.sdata' or `sbss' in any case). The size ofan object in the `.bss' section is set by the `.comm' or `.lcomm'directive that defines it. The size of an external object may be setwith the `.extern' directive. For example, `.extern sym,4' declaresthat the object at `sym' is 4 bytes in length, whie leaving `sym'otherwise undefined.Using small ECOFF objects requires linker support, and assumes thatthe `$gp' register is correctly initialized (normally doneautomatically by the startup code). MIPS ECOFF assembly code must notmodify the `$gp' register.File: as.info, Node: MIPS Stabs, Next: MIPS ISA, Prev: MIPS Object, Up: MIPS-Dependent9.22.3 Directives for debugging information-------------------------------------------MIPS ECOFF `as' supports several directives used for generatingdebugging information which are not support by traditional MIPSassemblers. These are `.def', `.endef', `.dim', `.file', `.scl',`.size', `.tag', `.type', `.val', `.stabd', `.stabn', and `.stabs'.The debugging information generated by the three `.stab' directives canonly be read by GDB, not by traditional MIPS debuggers (thisenhancement is required to fully support C++ debugging). Thesedirectives are primarily used by compilers, not assembly languageprogrammers!File: as.info, Node: MIPS symbol sizes, Next: MIPS autoextend, Prev: MIPS ISA, Up: MIPS-Dependent9.22.4 Directives to override the size of symbols-------------------------------------------------The n64 ABI allows symbols to have any 64-bit value. Although thisprovides a great deal of flexibility, it means that some macros havemuch longer expansions than their 32-bit counterparts. For example,the non-PIC expansion of `dla $4,sym' is usually:lui $4,%highest(sym)lui $1,%hi(sym)daddiu $4,$4,%higher(sym)daddiu $1,$1,%lo(sym)dsll32 $4,$4,0daddu $4,$4,$1whereas the 32-bit expansion is simply:lui $4,%hi(sym)daddiu $4,$4,%lo(sym)n64 code is sometimes constructed in such a way that all symbolicconstants are known to have 32-bit values, and in such cases, it'spreferable to use the 32-bit expansion instead of the 64-bit expansion.You can use the `.set sym32' directive to tell the assembler that,from this point on, all expressions of the form `SYMBOL' or `SYMBOL +OFFSET' have 32-bit values. For example:.set sym32dla $4,symlw $4,sym+16sw $4,sym+0x8000($4)will cause the assembler to treat `sym', `sym+16' and `sym+0x8000'as 32-bit values. The handling of non-symbolic addresses is notaffected.The directive `.set nosym32' ends a `.set sym32' block and revertsto the normal behavior. It is also possible to change the symbol sizeusing the command-line options `-msym32' and `-mno-sym32'.These options and directives are always accepted, but at present,they have no effect for anything other than n64.File: as.info, Node: MIPS ISA, Next: MIPS symbol sizes, Prev: MIPS Stabs, Up: MIPS-Dependent9.22.5 Directives to override the ISA level-------------------------------------------GNU `as' supports an additional directive to change the MIPSInstruction Set Architecture level on the fly: `.set mipsN'. N shouldbe a number from 0 to 5, or 32, 32r2, 64 or 64r2. The values otherthan 0 make the assembler accept instructions for the corresponding ISAlevel, from that point on in the assembly. `.set mipsN' affects notonly which instructions are permitted, but also how certain macros areexpanded. `.set mips0' restores the ISA level to its original level:either the level you selected with command line options, or the defaultfor your configuration. You can use this feature to permit specificMIPS3 instructions while assembling in 32 bit mode. Use this directivewith care!The `.set arch=CPU' directive provides even finer control. Itchanges the effective CPU target and allows the assembler to useinstructions specific to a particular CPU. All CPUs supported by the`-march' command line option are also selectable by this directive.The original value is restored by `.set arch=default'.The directive `.set mips16' puts the assembler into MIPS 16 mode, inwhich it will assemble instructions for the MIPS 16 processor. Use`.set nomips16' to return to normal 32 bit mode.Traditional MIPS assemblers do not support this directive.File: as.info, Node: MIPS autoextend, Next: MIPS insn, Prev: MIPS symbol sizes, Up: MIPS-Dependent9.22.6 Directives for extending MIPS 16 bit instructions--------------------------------------------------------By default, MIPS 16 instructions are automatically extended to 32 bitswhen necessary. The directive `.set noautoextend' will turn this off.When `.set noautoextend' is in effect, any 32 bit instruction must beexplicitly extended with the `.e' modifier (e.g., `li.e $4,1000'). Thedirective `.set autoextend' may be used to once again automaticallyextend instructions when necessary.This directive is only meaningful when in MIPS 16 mode. TraditionalMIPS assemblers do not support this directive.File: as.info, Node: MIPS insn, Next: MIPS option stack, Prev: MIPS autoextend, Up: MIPS-Dependent9.22.7 Directive to mark data as an instruction-----------------------------------------------The `.insn' directive tells `as' that the following data is actuallyinstructions. This makes a difference in MIPS 16 mode: when loadingthe address of a label which precedes instructions, `as' automaticallyadds 1 to the value, so that jumping to the loaded address will do theright thing.File: as.info, Node: MIPS option stack, Next: MIPS ASE instruction generation overrides, Prev: MIPS insn, Up: MIPS-Dependent9.22.8 Directives to save and restore options---------------------------------------------The directives `.set push' and `.set pop' may be used to save andrestore the current settings for all the options which are controlledby `.set'. The `.set push' directive saves the current settings on astack. The `.set pop' directive pops the stack and restores thesettings.These directives can be useful inside an macro which must change anoption such as the ISA level or instruction reordering but does not wantto change the state of the code which invoked the macro.Traditional MIPS assemblers do not support these directives.File: as.info, Node: MIPS ASE instruction generation overrides, Next: MIPS floating-point, Prev: MIPS option stack, Up: MIPS-Dependent9.22.9 Directives to control generation of MIPS ASE instructions----------------------------------------------------------------The directive `.set mips3d' makes the assembler accept instructionsfrom the MIPS-3D Application Specific Extension from that point on inthe assembly. The `.set nomips3d' directive prevents MIPS-3Dinstructions from being accepted.The directive `.set smartmips' makes the assembler acceptinstructions from the SmartMIPS Application Specific Extension to theMIPS32 ISA from that point on in the assembly. The `.set nosmartmips'directive prevents SmartMIPS instructions from being accepted.The directive `.set mdmx' makes the assembler accept instructionsfrom the MDMX Application Specific Extension from that point on in theassembly. The `.set nomdmx' directive prevents MDMX instructions frombeing accepted.The directive `.set dsp' makes the assembler accept instructionsfrom the DSP Release 1 Application Specific Extension from that pointon in the assembly. The `.set nodsp' directive prevents DSP Release 1instructions from being accepted.The directive `.set dspr2' makes the assembler accept instructionsfrom the DSP Release 2 Application Specific Extension from that pointon in the assembly. This dirctive implies `.set dsp'. The `.setnodspr2' directive prevents DSP Release 2 instructions from beingaccepted.The directive `.set mt' makes the assembler accept instructions fromthe MT Application Specific Extension from that point on in theassembly. The `.set nomt' directive prevents MT instructions frombeing accepted.Traditional MIPS assemblers do not support these directives.File: as.info, Node: MIPS floating-point, Prev: MIPS ASE instruction generation overrides, Up: MIPS-Dependent9.22.10 Directives to override floating-point options-----------------------------------------------------The directives `.set softfloat' and `.set hardfloat' provide finercontrol of disabling and enabling float-point instructions. Thesedirectives always override the default (that hard-float instructionsare accepted) or the command-line options (`-msoft-float' and`-mhard-float').The directives `.set singlefloat' and `.set doublefloat' providefiner control of disabling and enabling double-precision float-pointoperations. These directives always override the default (thatdouble-precision operations are accepted) or the command-line options(`-msingle-float' and `-mdouble-float').Traditional MIPS assemblers do not support these directives.File: as.info, Node: MMIX-Dependent, Next: MSP430-Dependent, Prev: MIPS-Dependent, Up: Machine Dependencies9.23 MMIX Dependent Features============================* Menu:* MMIX-Opts:: Command-line Options* MMIX-Expand:: Instruction expansion* MMIX-Syntax:: Syntax* MMIX-mmixal:: Differences to `mmixal' syntax and semanticsFile: as.info, Node: MMIX-Opts, Next: MMIX-Expand, Up: MMIX-Dependent9.23.1 Command-line Options---------------------------The MMIX version of `as' has some machine-dependent options.When `--fixed-special-register-names' is specified, only the registernames specified in *Note MMIX-Regs:: are recognized in the instructions`PUT' and `GET'.You can use the `--globalize-symbols' to make all symbols global.This option is useful when splitting up a `mmixal' program into severalfiles.The `--gnu-syntax' turns off most syntax compatibility with`mmixal'. Its usability is currently doubtful.The `--relax' option is not fully supported, but will eventually makethe object file prepared for linker relaxation.If you want to avoid inadvertently calling a predefined symbol andwould rather get an error, for example when using `as' with a compileror other machine-generated code, specify `--no-predefined-syms'. Thisturns off built-in predefined definitions of all such symbols,including rounding-mode symbols, segment symbols, `BIT' symbols, and`TRAP' symbols used in `mmix' "system calls". It also turns offpredefined special-register names, except when used in `PUT' and `GET'instructions.By default, some instructions are expanded to fit the size of theoperand or an external symbol (*note MMIX-Expand::). By passing`--no-expand', no such expansion will be done, instead causing errorsat link time if the operand does not fit.The `mmixal' documentation (*note mmixsite::) specifies that globalregisters allocated with the `GREG' directive (*note MMIX-greg::) andinitialized to the same non-zero value, will refer to the same globalregister. This isn't strictly enforceable in `as' since the finaladdresses aren't known until link-time, but it will do an effort unlessthe `--no-merge-gregs' option is specified. (Register merging isn'tyet implemented in `ld'.)`as' will warn every time it expands an instruction to fit anoperand unless the option `-x' is specified. It is believed that thisbehaviour is more useful than just mimicking `mmixal''s behaviour, inwhich instructions are only expanded if the `-x' option is specified,and assembly fails otherwise, when an instruction needs to be expanded.It needs to be kept in mind that `mmixal' is both an assembler andlinker, while `as' will expand instructions that at link stage can becontracted. (Though linker relaxation isn't yet implemented in `ld'.)The option `-x' also imples `--linker-allocated-gregs'.If instruction expansion is enabled, `as' can expand a `PUSHJ'instruction into a series of instructions. The shortest expansion isto not expand it, but just mark the call as redirectable to a stub,which `ld' creates at link-time, but only if the original `PUSHJ'instruction is found not to reach the target. The stub consists of thenecessary instructions to form a jump to the target. This happens if`as' can assert that the `PUSHJ' instruction can reach such a stub.The option `--no-pushj-stubs' disables this shorter expansion, and thelonger series of instructions is then created at assembly-time. Theoption `--no-stubs' is a synonym, intended for compatibility withfuture releases, where generation of stubs for other instructions maybe implemented.Usually a two-operand-expression (*note GREG-base::) without amatching `GREG' directive is treated as an error by `as'. When theoption `--linker-allocated-gregs' is in effect, they are instead passedthrough to the linker, which will allocate as many global registers asis needed.File: as.info, Node: MMIX-Expand, Next: MMIX-Syntax, Prev: MMIX-Opts, Up: MMIX-Dependent9.23.2 Instruction expansion----------------------------When `as' encounters an instruction with an operand that is either notknown or does not fit the operand size of the instruction, `as' (and`ld') will expand the instruction into a sequence of instructionssemantically equivalent to the operand fitting the instruction.Expansion will take place for the following instructions:`GETA'Expands to a sequence of four instructions: `SETL', `INCML',`INCMH' and `INCH'. The operand must be a multiple of four.Conditional branchesA branch instruction is turned into a branch with the complementedcondition and prediction bit over five instructions; fourinstructions setting `$255' to the operand value, which like with`GETA' must be a multiple of four, and a final `GO $255,$255,0'.`PUSHJ'Similar to expansion for conditional branches; four instructionsset `$255' to the operand value, followed by a `PUSHGO$255,$255,0'.`JMP'Similar to conditional branches and `PUSHJ'. The final instructionis `GO $255,$255,0'.The linker `ld' is expected to shrink these expansions for codeassembled with `--relax' (though not currently implemented).File: as.info, Node: MMIX-Syntax, Next: MMIX-mmixal, Prev: MMIX-Expand, Up: MMIX-Dependent9.23.3 Syntax-------------The assembly syntax is supposed to be upward compatible with thatdescribed in Sections 1.3 and 1.4 of `The Art of Computer Programming,Volume 1'. Draft versions of those chapters as well as other MMIXinformation is located at`http://www-cs-faculty.stanford.edu/~knuth/mmix-news.html'. Most codeexamples from the mmixal package located there should work unmodifiedwhen assembled and linked as single files, with a few noteworthyexceptions (*note MMIX-mmixal::).Before an instruction is emitted, the current location is aligned tothe next four-byte boundary. If a label is defined at the beginning ofthe line, its value will be the aligned value.In addition to the traditional hex-prefix `0x', a hexadecimal numbercan also be specified by the prefix character `#'.After all operands to an MMIX instruction or directive have beenspecified, the rest of the line is ignored, treated as a comment.* Menu:* MMIX-Chars:: Special Characters* MMIX-Symbols:: Symbols* MMIX-Regs:: Register Names* MMIX-Pseudos:: Assembler DirectivesFile: as.info, Node: MMIX-Chars, Next: MMIX-Symbols, Up: MMIX-Syntax9.23.3.1 Special Characters...........................The characters `*' and `#' are line comment characters; each start acomment at the beginning of a line, but only at the beginning of aline. A `#' prefixes a hexadecimal number if found elsewhere on a line.Two other characters, `%' and `!', each start a comment anywhere onthe line. Thus you can't use the `modulus' and `not' operators inexpressions normally associated with these two characters.A `;' is a line separator, treated as a new-line, so separateinstructions can be specified on a single line.File: as.info, Node: MMIX-Symbols, Next: MMIX-Regs, Prev: MMIX-Chars, Up: MMIX-Syntax9.23.3.2 Symbols................The character `:' is permitted in identifiers. There are twoexceptions to it being treated as any other symbol character: if asymbol begins with `:', it means that the symbol is in the globalnamespace and that the current prefix should not be prepended to thatsymbol (*note MMIX-prefix::). The `:' is then not considered part ofthe symbol. For a symbol in the label position (first on a line), a `:'at the end of a symbol is silently stripped off. A label is permitted,but not required, to be followed by a `:', as with many other assemblyformats.The character `@' in an expression, is a synonym for `.', thecurrent location.In addition to the common forward and backward local symbol formats(*note Symbol Names::), they can be specified with upper-case `B' and`F', as in `8B' and `9F'. A local label defined for the currentposition is written with a `H' appended to the number:3H LDB $0,$1,2This and traditional local-label formats cannot be mixed: a labelmust be defined and referred to using the same format.There's a minor caveat: just as for the ordinary local symbols, thelocal symbols are translated into ordinary symbols using controlcharacters are to hide the ordinal number of the symbol.Unfortunately, these symbols are not translated back in error messages.Thus you may see confusing error messages when local symbols are used.Control characters `\003' (control-C) and `\004' (control-D) are usedfor the MMIX-specific local-symbol syntax.The symbol `Main' is handled specially; it is always global.By defining the symbols `__.MMIX.start..text' and`__.MMIX.start..data', the address of respectively the `.text' and`.data' segments of the final program can be defined, though whenlinking more than one object file, the code or data in the object filecontaining the symbol is not guaranteed to be start at that position;just the final executable. *Note MMIX-loc::.File: as.info, Node: MMIX-Regs, Next: MMIX-Pseudos, Prev: MMIX-Symbols, Up: MMIX-Syntax9.23.3.3 Register names.......................Local and global registers are specified as `$0' to `$255'. Therecognized special register names are `rJ', `rA', `rB', `rC', `rD',`rE', `rF', `rG', `rH', `rI', `rK', `rL', `rM', `rN', `rO', `rP', `rQ',`rR', `rS', `rT', `rU', `rV', `rW', `rX', `rY', `rZ', `rBB', `rTT',`rWW', `rXX', `rYY' and `rZZ'. A leading `:' is optional for specialregister names.Local and global symbols can be equated to register names and used inplace of ordinary registers.Similarly for special registers, local and global symbols can beused. Also, symbols equated from numbers and constant expressions areallowed in place of a special register, except when either of theoptions `--no-predefined-syms' and `--fixed-special-register-names' arespecified. Then only the special register names above are allowed forthe instructions having a special register operand; `GET' and `PUT'.File: as.info, Node: MMIX-Pseudos, Prev: MMIX-Regs, Up: MMIX-Syntax9.23.3.4 Assembler Directives.............................`LOC'The `LOC' directive sets the current location to the value of theoperand field, which may include changing sections. If theoperand is a constant, the section is set to either `.data' if thevalue is `0x2000000000000000' or larger, else it is set to `.text'.Within a section, the current location may only be changed tomonotonically higher addresses. A LOC expression must be apreviously defined symbol or a "pure" constant.An example, which sets the label PREV to the current location, andupdates the current location to eight bytes forward:prev LOC @+8When a LOC has a constant as its operand, a symbol`__.MMIX.start..text' or `__.MMIX.start..data' is defineddepending on the address as mentioned above. Each such symbol isinterpreted as special by the linker, locating the section at thataddress. Note that if multiple files are linked, the first objectfile with that section will be mapped to that address (notnecessarily the file with the LOC definition).`LOCAL'Example:LOCAL external_symbolLOCAL 42.local asymbolThis directive-operation generates a link-time assertion that theoperand does not correspond to a global register. The operand isan expression that at link-time resolves to a register symbol or anumber. A number is treated as the register having that number.There is one restriction on the use of this directive: thepseudo-directive must be placed in a section with contents, codeor data.`IS'The `IS' directive:asymbol IS an_expressionsets the symbol `asymbol' to `an_expression'. A symbol may not beset more than once using this directive. Local labels may be setusing this directive, for example:5H IS @+4`GREG'This directive reserves a global register, gives it an initialvalue and optionally gives it a symbolic name. Some examples:areg GREGbreg GREG data_valueGREG data_buffer.greg creg, another_data_valueThe symbolic register name can be used in place of a (non-special)register. If a value isn't provided, it defaults to zero. Unlessthe option `--no-merge-gregs' is specified, non-zero registersallocated with this directive may be eliminated by `as'; anotherregister with the same value used in its place. Any of theinstructions `CSWAP', `GO', `LDA', `LDBU', `LDB', `LDHT', `LDOU',`LDO', `LDSF', `LDTU', `LDT', `LDUNC', `LDVTS', `LDWU', `LDW',`PREGO', `PRELD', `PREST', `PUSHGO', `STBU', `STB', `STCO', `STHT',`STOU', `STSF', `STTU', `STT', `STUNC', `SYNCD', `SYNCID', canhave a value nearby an initial value in place of its second andthird operands. Here, "nearby" is defined as within the range0...255 from the initial value of such an allocated register.buffer1 BYTE 0,0,0,0,0buffer2 BYTE 0,0,0,0,0...GREG buffer1LDOU $42,buffer2In the example above, the `Y' field of the `LDOUI' instruction(LDOU with a constant Z) will be replaced with the global registerallocated for `buffer1', and the `Z' field will have the value 5,the offset from `buffer1' to `buffer2'. The result is equivalentto this code:buffer1 BYTE 0,0,0,0,0buffer2 BYTE 0,0,0,0,0...tmpreg GREG buffer1LDOU $42,tmpreg,(buffer2-buffer1)Global registers allocated with this directive are allocated inorder higher-to-lower within a file. Other than that, the exactorder of register allocation and elimination is undefined. Forexample, the order is undefined when more than one file with suchdirectives are linked together. With the options `-x' and`--linker-allocated-gregs', `GREG' directives for two-operandcases like the one mentioned above can be omitted. Sufficientglobal registers will then be allocated by the linker.`BYTE'The `BYTE' directive takes a series of operands separated by acomma. If an operand is a string (*note Strings::), eachcharacter of that string is emitted as a byte. Other operandsmust be constant expressions without forward references, in therange 0...255. If you need operands having expressions withforward references, use `.byte' (*note Byte::). An operand can beomitted, defaulting to a zero value.`WYDE'`TETRA'`OCTA'The directives `WYDE', `TETRA' and `OCTA' emit constants of two,four and eight bytes size respectively. Before anything elsehappens for the directive, the current location is aligned to therespective constant-size boundary. If a label is defined at thebeginning of the line, its value will be that after the alignment.A single operand can be omitted, defaulting to a zero valueemitted for the directive. Operands can be expressed as strings(*note Strings::), in which case each character in the string isemitted as a separate constant of the size indicated by thedirective.`PREFIX'The `PREFIX' directive sets a symbol name prefix to be prepended toall symbols (except local symbols, *note MMIX-Symbols::), that arenot prefixed with `:', until the next `PREFIX' directive. Suchprefixes accumulate. For example,PREFIX aPREFIX bc IS 0defines a symbol `abc' with the value 0.`BSPEC'`ESPEC'A pair of `BSPEC' and `ESPEC' directives delimit a section ofspecial contents (without specified semantics). Example:BSPEC 42TETRA 1,2,3ESPECThe single operand to `BSPEC' must be number in the range 0...255.The `BSPEC' number 80 is used by the GNU binutils implementation.File: as.info, Node: MMIX-mmixal, Prev: MMIX-Syntax, Up: MMIX-Dependent9.23.4 Differences to `mmixal'------------------------------The binutils `as' and `ld' combination has a few differences infunction compared to `mmixal' (*note mmixsite::).The replacement of a symbol with a GREG-allocated register (*noteGREG-base::) is not handled the exactly same way in `as' as in`mmixal'. This is apparent in the `mmixal' example file `inout.mms',where different registers with different offsets, eventually yieldingthe same address, are used in the first instruction. This type ofdifference should however not affect the function of any program unlessit has specific assumptions about the allocated register number.Line numbers (in the `mmo' object format) are currently notsupported.Expression operator precedence is not that of mmixal: operatorprecedence is that of the C programming language. It's recommended touse parentheses to explicitly specify wanted operator precedencewhenever more than one type of operators are used.The serialize unary operator `&', the fractional division operator`//', the logical not operator `!' and the modulus operator `%' are notavailable.Symbols are not global by default, unless the option`--globalize-symbols' is passed. Use the `.global' directive toglobalize symbols (*note Global::).Operand syntax is a bit stricter with `as' than `mmixal'. Forexample, you can't say `addu 1,2,3', instead you must write `addu$1,$2,3'.You can't LOC to a lower address than those already visited (i.e.,"backwards").A LOC directive must come before any emitted code.Predefined symbols are visible as file-local symbols after use. (Inthe ELF file, that is--the linked mmo file has no notion of a file-localsymbol.)Some mapping of constant expressions to sections in LOC expressionsis attempted, but that functionality is easily confused and should beavoided unless compatibility with `mmixal' is required. A LOCexpression to `0x2000000000000000' or higher, maps to the `.data'section and lower addresses map to the `.text' section (*noteMMIX-loc::).The code and data areas are each contiguous. Sparse programs withfar-away LOC directives will take up the same amount of space as acontiguous program with zeros filled in the gaps between the LOCdirectives. If you need sparse programs, you might try and get thewanted effect with a linker script and splitting up the code parts intosections (*note Section::). Assembly code for this, to be compatiblewith `mmixal', would look something like:.if 0LOC away_expression.else.section away,"ax".fi`as' will not execute the LOC directive and `mmixal' ignores thelines with `.'. This construct can be used generally to helpcompatibility.Symbols can't be defined twice-not even to the same value.Instruction mnemonics are recognized case-insensitive, though the`IS' and `GREG' pseudo-operations must be specified in upper-casecharacters.There's no unicode support.The following is a list of programs in `mmix.tar.gz', available at`http://www-cs-faculty.stanford.edu/~knuth/mmix-news.html', lastchecked with the version dated 2001-08-25 (md5sumc393470cfc86fac040487d22d2bf0172) that assemble with `mmixal' but donot assemble with `as':`silly.mms'LOC to a previous address.`sim.mms'Redefines symbol `Done'.`test.mms'Uses the serial operator `&'.File: as.info, Node: MSP430-Dependent, Next: SH-Dependent, Prev: MMIX-Dependent, Up: Machine Dependencies9.24 MSP 430 Dependent Features===============================* Menu:* MSP430 Options:: Options* MSP430 Syntax:: Syntax* MSP430 Floating Point:: Floating Point* MSP430 Directives:: MSP 430 Machine Directives* MSP430 Opcodes:: Opcodes* MSP430 Profiling Capability:: Profiling CapabilityFile: as.info, Node: MSP430 Options, Next: MSP430 Syntax, Up: MSP430-Dependent9.24.1 Options--------------`-m'select the mpu arch. Currently has no effect.`-mP'enables polymorph instructions handler.`-mQ'enables relaxation at assembly time. DANGEROUS!File: as.info, Node: MSP430 Syntax, Next: MSP430 Floating Point, Prev: MSP430 Options, Up: MSP430-Dependent9.24.2 Syntax-------------* Menu:* MSP430-Macros:: Macros* MSP430-Chars:: Special Characters* MSP430-Regs:: Register Names* MSP430-Ext:: Assembler ExtensionsFile: as.info, Node: MSP430-Macros, Next: MSP430-Chars, Up: MSP430 Syntax9.24.2.1 Macros...............The macro syntax used on the MSP 430 is like that described in the MSP430 Family Assembler Specification. Normal `as' macros should stillwork.Additional built-in macros are:`llo(exp)'Extracts least significant word from 32-bit expression 'exp'.`lhi(exp)'Extracts most significant word from 32-bit expression 'exp'.`hlo(exp)'Extracts 3rd word from 64-bit expression 'exp'.`hhi(exp)'Extracts 4rd word from 64-bit expression 'exp'.They normally being used as an immediate source operand.mov #llo(1), r10 ; == mov #1, r10mov #lhi(1), r10 ; == mov #0, r10File: as.info, Node: MSP430-Chars, Next: MSP430-Regs, Prev: MSP430-Macros, Up: MSP430 Syntax9.24.2.2 Special Characters...........................`;' is the line comment character.The character `$' in jump instructions indicates current location andimplemented only for TI syntax compatibility.File: as.info, Node: MSP430-Regs, Next: MSP430-Ext, Prev: MSP430-Chars, Up: MSP430 Syntax9.24.2.3 Register Names.......................General-purpose registers are represented by predefined symbols of theform `rN' (for global registers), where N represents a number between`0' and `15'. The leading letters may be in either upper or lowercase; for example, `r13' and `R7' are both valid register names.Register names `PC', `SP' and `SR' cannot be used as register namesand will be treated as variables. Use `r0', `r1', and `r2' instead.File: as.info, Node: MSP430-Ext, Prev: MSP430-Regs, Up: MSP430 Syntax9.24.2.4 Assembler Extensions.............................`@rN'As destination operand being treated as `0(rn)'`0(rN)'As source operand being treated as `@rn'`jCOND +N'Skips next N bytes followed by jump instruction and equivalent to`jCOND $+N+2'Also, there are some instructions, which cannot be found in otherassemblers. These are branch instructions, which has different opcodesupon jump distance. They all got PC relative addressing mode.`beq label'A polymorph instruction which is `jeq label' in case if jumpdistance within allowed range for cpu's jump instruction. If not,this unrolls into a sequence ofjne $+6br label`bne label'A polymorph instruction which is `jne label' or `jeq +4; br label'`blt label'A polymorph instruction which is `jl label' or `jge +4; br label'`bltn label'A polymorph instruction which is `jn label' or `jn +2; jmp +4; brlabel'`bltu label'A polymorph instruction which is `jlo label' or `jhs +2; br label'`bge label'A polymorph instruction which is `jge label' or `jl +4; br label'`bgeu label'A polymorph instruction which is `jhs label' or `jlo +4; br label'`bgt label'A polymorph instruction which is `jeq +2; jge label' or `jeq +6;jl +4; br label'`bgtu label'A polymorph instruction which is `jeq +2; jhs label' or `jeq +6;jlo +4; br label'`bleu label'A polymorph instruction which is `jeq label; jlo label' or `jeq+2; jhs +4; br label'`ble label'A polymorph instruction which is `jeq label; jl label' or `jeq+2; jge +4; br label'`jump label'A polymorph instruction which is `jmp label' or `br label'File: as.info, Node: MSP430 Floating Point, Next: MSP430 Directives, Prev: MSP430 Syntax, Up: MSP430-Dependent9.24.3 Floating Point---------------------The MSP 430 family uses IEEE 32-bit floating-point numbers.File: as.info, Node: MSP430 Directives, Next: MSP430 Opcodes, Prev: MSP430 Floating Point, Up: MSP430-Dependent9.24.4 MSP 430 Machine Directives---------------------------------`.file'This directive is ignored; it is accepted for compatibility withother MSP 430 assemblers._Warning:_ in other versions of the GNU assembler, `.file' isused for the directive called `.app-file' in the MSP 430support.`.line'This directive is ignored; it is accepted for compatibility withother MSP 430 assemblers.`.arch'Currently this directive is ignored; it is accepted forcompatibility with other MSP 430 assemblers.`.profiler'This directive instructs assembler to add new profile entry to theobject file.File: as.info, Node: MSP430 Opcodes, Next: MSP430 Profiling Capability, Prev: MSP430 Directives, Up: MSP430-Dependent9.24.5 Opcodes--------------`as' implements all the standard MSP 430 opcodes. No additionalpseudo-instructions are needed on this family.For information on the 430 machine instruction set, see `MSP430User's Manual, document slau049d', Texas Instrument, Inc.File: as.info, Node: MSP430 Profiling Capability, Prev: MSP430 Opcodes, Up: MSP430-Dependent9.24.6 Profiling Capability---------------------------It is a performance hit to use gcc's profiling approach for this tinytarget. Even more - jtag hardware facility does not perform anyprofiling functions. However we've got gdb's built-in simulator wherewe can do anything.We define new section `.profiler' which holds all profilinginformation. We define new pseudo operation `.profiler' which willinstruct assembler to add new profile entry to the object file. Profileshould take place at the present address.Pseudo operation format:`.profiler flags,function_to_profile [, cycle_corrector, extra]'where:`flags' is a combination of the following characters:`s'function entry`x'function exit`i'function is in init section`f'function is in fini section`l'library call`c'libc standard call`d'stack value demand`I'interrupt service routine`P'prologue start`p'prologue end`E'epilogue start`e'epilogue end`j'long jump / sjlj unwind`a'an arbitrary code fragment`t'extra parameter saved (a constant value like frame size)`function_to_profile'a function address`cycle_corrector'a value which should be added to the cycle counter, zero ifomitted.`extra'any extra parameter, zero if omitted.For example:.global fxx.type fxx,@functionfxx:.LFrameOffset_fxx=0x08.profiler "scdP", fxx ; function entry.; we also demand stack value to be savedpush r11push r10push r9push r8.profiler "cdpt",fxx,0, .LFrameOffset_fxx ; check stack value at this point; (this is a prologue end); note, that spare var filled with; the farme sizemov r15,r8....profiler cdE,fxx ; check stackpop r8pop r9pop r10pop r11.profiler xcde,fxx,3 ; exit adds 3 to the cycle counterret ; cause 'ret' insn takes 3 cyclesFile: as.info, Node: PDP-11-Dependent, Next: PJ-Dependent, Prev: SH64-Dependent, Up: Machine Dependencies9.25 PDP-11 Dependent Features==============================* Menu:* PDP-11-Options:: Options* PDP-11-Pseudos:: Assembler Directives* PDP-11-Syntax:: DEC Syntax versus BSD Syntax* PDP-11-Mnemonics:: Instruction Naming* PDP-11-Synthetic:: Synthetic InstructionsFile: as.info, Node: PDP-11-Options, Next: PDP-11-Pseudos, Up: PDP-11-Dependent9.25.1 Options--------------The PDP-11 version of `as' has a rich set of machine dependent options.9.25.1.1 Code Generation Options................................`-mpic | -mno-pic'Generate position-independent (or position-dependent) code.The default is to generate position-independent code.9.25.1.2 Instruction Set Extension Options..........................................These options enables or disables the use of extensions over the baseline instruction set as introduced by the first PDP-11 CPU: the KA11.Most options come in two variants: a `-m'EXTENSION that enablesEXTENSION, and a `-mno-'EXTENSION that disables EXTENSION.The default is to enable all extensions.`-mall | -mall-extensions'Enable all instruction set extensions.`-mno-extensions'Disable all instruction set extensions.`-mcis | -mno-cis'Enable (or disable) the use of the commercial instruction set,which consists of these instructions: `ADDNI', `ADDN', `ADDPI',`ADDP', `ASHNI', `ASHN', `ASHPI', `ASHP', `CMPCI', `CMPC',`CMPNI', `CMPN', `CMPPI', `CMPP', `CVTLNI', `CVTLN', `CVTLPI',`CVTLP', `CVTNLI', `CVTNL', `CVTNPI', `CVTNP', `CVTPLI', `CVTPL',`CVTPNI', `CVTPN', `DIVPI', `DIVP', `L2DR', `L3DR', `LOCCI',`LOCC', `MATCI', `MATC', `MOVCI', `MOVC', `MOVRCI', `MOVRC',`MOVTCI', `MOVTC', `MULPI', `MULP', `SCANCI', `SCANC', `SKPCI',`SKPC', `SPANCI', `SPANC', `SUBNI', `SUBN', `SUBPI', and `SUBP'.`-mcsm | -mno-csm'Enable (or disable) the use of the `CSM' instruction.`-meis | -mno-eis'Enable (or disable) the use of the extended instruction set, whichconsists of these instructions: `ASHC', `ASH', `DIV', `MARK',`MUL', `RTT', `SOB' `SXT', and `XOR'.`-mfis | -mkev11'`-mno-fis | -mno-kev11'Enable (or disable) the use of the KEV11 floating-pointinstructions: `FADD', `FDIV', `FMUL', and `FSUB'.`-mfpp | -mfpu | -mfp-11'`-mno-fpp | -mno-fpu | -mno-fp-11'Enable (or disable) the use of FP-11 floating-point instructions:`ABSF', `ADDF', `CFCC', `CLRF', `CMPF', `DIVF', `LDCFF', `LDCIF',`LDEXP', `LDF', `LDFPS', `MODF', `MULF', `NEGF', `SETD', `SETF',`SETI', `SETL', `STCFF', `STCFI', `STEXP', `STF', `STFPS', `STST',`SUBF', and `TSTF'.`-mlimited-eis | -mno-limited-eis'Enable (or disable) the use of the limited extended instructionset: `MARK', `RTT', `SOB', `SXT', and `XOR'.The -mno-limited-eis options also implies -mno-eis.`-mmfpt | -mno-mfpt'Enable (or disable) the use of the `MFPT' instruction.`-mmultiproc | -mno-multiproc'Enable (or disable) the use of multiprocessor instructions:`TSTSET' and `WRTLCK'.`-mmxps | -mno-mxps'Enable (or disable) the use of the `MFPS' and `MTPS' instructions.`-mspl | -mno-spl'Enable (or disable) the use of the `SPL' instruction.Enable (or disable) the use of the microcode instructions: `LDUB',`MED', and `XFC'.9.25.1.3 CPU Model Options..........................These options enable the instruction set extensions supported by aparticular CPU, and disables all other extensions.`-mka11'KA11 CPU. Base line instruction set only.`-mkb11'KB11 CPU. Enable extended instruction set and `SPL'.`-mkd11a'KD11-A CPU. Enable limited extended instruction set.`-mkd11b'KD11-B CPU. Base line instruction set only.`-mkd11d'KD11-D CPU. Base line instruction set only.`-mkd11e'KD11-E CPU. Enable extended instruction set, `MFPS', and `MTPS'.`-mkd11f | -mkd11h | -mkd11q'KD11-F, KD11-H, or KD11-Q CPU. Enable limited extendedinstruction set, `MFPS', and `MTPS'.`-mkd11k'KD11-K CPU. Enable extended instruction set, `LDUB', `MED',`MFPS', `MFPT', `MTPS', and `XFC'.`-mkd11z'KD11-Z CPU. Enable extended instruction set, `CSM', `MFPS',`MFPT', `MTPS', and `SPL'.`-mf11'F11 CPU. Enable extended instruction set, `MFPS', `MFPT', and`MTPS'.`-mj11'J11 CPU. Enable extended instruction set, `CSM', `MFPS', `MFPT',`MTPS', `SPL', `TSTSET', and `WRTLCK'.`-mt11'T11 CPU. Enable limited extended instruction set, `MFPS', and`MTPS'.9.25.1.4 Machine Model Options..............................These options enable the instruction set extensions supported by aparticular machine model, and disables all other extensions.`-m11/03'Same as `-mkd11f'.`-m11/04'Same as `-mkd11d'.`-m11/05 | -m11/10'Same as `-mkd11b'.`-m11/15 | -m11/20'Same as `-mka11'.`-m11/21'Same as `-mt11'.`-m11/23 | -m11/24'Same as `-mf11'.`-m11/34'Same as `-mkd11e'.`-m11/34a'Ame as `-mkd11e' `-mfpp'.`-m11/35 | -m11/40'Same as `-mkd11a'.`-m11/44'Same as `-mkd11z'.`-m11/45 | -m11/50 | -m11/55 | -m11/70'Same as `-mkb11'.`-m11/53 | -m11/73 | -m11/83 | -m11/84 | -m11/93 | -m11/94'Same as `-mj11'.`-m11/60'Same as `-mkd11k'.File: as.info, Node: PDP-11-Pseudos, Next: PDP-11-Syntax, Prev: PDP-11-Options, Up: PDP-11-Dependent9.25.2 Assembler Directives---------------------------The PDP-11 version of `as' has a few machine dependent assemblerdirectives.`.bss'Switch to the `bss' section.`.even'Align the location counter to an even number.File: as.info, Node: PDP-11-Syntax, Next: PDP-11-Mnemonics, Prev: PDP-11-Pseudos, Up: PDP-11-Dependent9.25.3 PDP-11 Assembly Language Syntax--------------------------------------`as' supports both DEC syntax and BSD syntax. The only difference isthat in DEC syntax, a `#' character is used to denote an immediateconstants, while in BSD syntax the character for this purpose is `$'.general-purpose registers are named `r0' through `r7'. Mnemonicalternatives for `r6' and `r7' are `sp' and `pc', respectively.Floating-point registers are named `ac0' through `ac3', oralternatively `fr0' through `fr3'.Comments are started with a `#' or a `/' character, and extend tothe end of the line. (FIXME: clash with immediates?)File: as.info, Node: PDP-11-Mnemonics, Next: PDP-11-Synthetic, Prev: PDP-11-Syntax, Up: PDP-11-Dependent9.25.4 Instruction Naming-------------------------Some instructions have alternative names.`BCC'`BHIS'`BCS'`BLO'`L2DR'`L2D'`L3DR'`L3D'`SYS'`TRAP'File: as.info, Node: PDP-11-Synthetic, Prev: PDP-11-Mnemonics, Up: PDP-11-Dependent9.25.5 Synthetic Instructions-----------------------------The `JBR' and `J'CC synthetic instructions are not supported yet.File: as.info, Node: PJ-Dependent, Next: PPC-Dependent, Prev: PDP-11-Dependent, Up: Machine Dependencies9.26 picoJava Dependent Features================================* Menu:* PJ Options:: OptionsFile: as.info, Node: PJ Options, Up: PJ-Dependent9.26.1 Options--------------`as' has two additional command-line options for the picoJavaarchitecture.`-ml'This option selects little endian data output.`-mb'This option selects big endian data output.File: as.info, Node: PPC-Dependent, Next: Sparc-Dependent, Prev: PJ-Dependent, Up: Machine Dependencies9.27 PowerPC Dependent Features===============================* Menu:* PowerPC-Opts:: Options* PowerPC-Pseudo:: PowerPC Assembler DirectivesFile: as.info, Node: PowerPC-Opts, Next: PowerPC-Pseudo, Up: PPC-Dependent9.27.1 Options--------------The PowerPC chip family includes several successive levels, using thesame core instruction set, but including a few additional instructionsat each level. There are exceptions to this however. For details onwhat instructions each variant supports, please see the chip'sarchitecture reference manual.The following table lists all available PowerPC options.`-mpwrx | -mpwr2'Generate code for POWER/2 (RIOS2).`-mpwr'Generate code for POWER (RIOS1)`-m601'Generate code for PowerPC 601.`-mppc, -mppc32, -m603, -m604'Generate code for PowerPC 603/604.`-m403, -m405'Generate code for PowerPC 403/405.`-m440'Generate code for PowerPC 440. BookE and some 405 instructions.`-m7400, -m7410, -m7450, -m7455'Generate code for PowerPC 7400/7410/7450/7455.`-m750cl'Generate code for PowerPC 750CL.`-mppc64, -m620'Generate code for PowerPC 620/625/630.`-me500, -me500x2'Generate code for Motorola e500 core complex.`-mspe'Generate code for Motorola SPE instructions.`-mppc64bridge'Generate code for PowerPC 64, including bridge insns.`-mbooke64'Generate code for 64-bit BookE.`-mbooke, mbooke32'Generate code for 32-bit BookE.`-me300'Generate code for PowerPC e300 family.`-maltivec'Generate code for processors with AltiVec instructions.`-mvsx'Generate code for processors with Vector-Scalar (VSX) instructions.`-mpower4'Generate code for Power4 architecture.`-mpower5'Generate code for Power5 architecture.`-mpower6'Generate code for Power6 architecture.`-mpower7'Generate code for Power7 architecture.`-mcell'Generate code for Cell Broadband Engine architecture.`-mcom'Generate code Power/PowerPC common instructions.`-many'Generate code for any architecture (PWR/PWRX/PPC).`-mregnames'Allow symbolic names for registers.`-mno-regnames'Do not allow symbolic names for registers.`-mrelocatable'Support for GCC's -mrelocatable option.`-mrelocatable-lib'Support for GCC's -mrelocatable-lib option.`-memb'Set PPC_EMB bit in ELF flags.`-mlittle, -mlittle-endian'Generate code for a little endian machine.`-mbig, -mbig-endian'Generate code for a big endian machine.`-msolaris'Generate code for Solaris.`-mno-solaris'Do not generate code for Solaris.File: as.info, Node: PowerPC-Pseudo, Prev: PowerPC-Opts, Up: PPC-Dependent9.27.2 PowerPC Assembler Directives-----------------------------------A number of assembler directives are available for PowerPC. Thefollowing table is far from complete.`.machine "string"'This directive allows you to change the machine for which code isgenerated. `"string"' may be any of the -m cpu selection options(without the -m) enclosed in double quotes, `"push"', or `"pop"'.`.machine "push"' saves the currently selected cpu, which may berestored with `.machine "pop"'.File: as.info, Node: SH-Dependent, Next: SH64-Dependent, Prev: MSP430-Dependent, Up: Machine Dependencies9.28 Renesas / SuperH SH Dependent Features===========================================* Menu:* SH Options:: Options* SH Syntax:: Syntax* SH Floating Point:: Floating Point* SH Directives:: SH Machine Directives* SH Opcodes:: OpcodesFile: as.info, Node: SH Options, Next: SH Syntax, Up: SH-Dependent9.28.1 Options--------------`as' has following command-line options for the Renesas (formerlyHitachi) / SuperH SH family.`--little'Generate little endian code.`--big'Generate big endian code.`--relax'Alter jump instructions for long displacements.`--small'Align sections to 4 byte boundaries, not 16.`--dsp'Enable sh-dsp insns, and disable sh3e / sh4 insns.`--renesas'Disable optimization with section symbol for compatibility withRenesas assembler.`--allow-reg-prefix'Allow '$' as a register name prefix.`--isa=sh4 | sh4a'Specify the sh4 or sh4a instruction set.`--isa=dsp'Enable sh-dsp insns, and disable sh3e / sh4 insns.`--isa=fp'Enable sh2e, sh3e, sh4, and sh4a insn sets.`--isa=all'Enable sh1, sh2, sh2e, sh3, sh3e, sh4, sh4a, and sh-dsp insn sets.`-h-tick-hex'Support H'00 style hex constants in addition to 0x00 style.File: as.info, Node: SH Syntax, Next: SH Floating Point, Prev: SH Options, Up: SH-Dependent9.28.2 Syntax-------------* Menu:* SH-Chars:: Special Characters* SH-Regs:: Register Names* SH-Addressing:: Addressing ModesFile: as.info, Node: SH-Chars, Next: SH-Regs, Up: SH Syntax9.28.2.1 Special Characters...........................`!' is the line comment character.You can use `;' instead of a newline to separate statements.Since `$' has no special meaning, you may use it in symbol names.File: as.info, Node: SH-Regs, Next: SH-Addressing, Prev: SH-Chars, Up: SH Syntax9.28.2.2 Register Names.......................You can use the predefined symbols `r0', `r1', `r2', `r3', `r4', `r5',`r6', `r7', `r8', `r9', `r10', `r11', `r12', `r13', `r14', and `r15' torefer to the SH registers.The SH also has these control registers:`pr'procedure register (holds return address)`pc'program counter`mach'`macl'high and low multiply accumulator registers`sr'status register`gbr'global base register`vbr'vector base register (for interrupt vectors)File: as.info, Node: SH-Addressing, Prev: SH-Regs, Up: SH Syntax9.28.2.3 Addressing Modes.........................`as' understands the following addressing modes for the SH. `RN' inthe following refers to any of the numbered registers, but _not_ thecontrol registers.`RN'Register direct`@RN'Register indirect`@-RN'Register indirect with pre-decrement`@RN+'Register indirect with post-increment`@(DISP, RN)'Register indirect with displacement`@(R0, RN)'Register indexed`@(DISP, GBR)'`GBR' offset`@(R0, GBR)'GBR indexed`ADDR'`@(DISP, PC)'PC relative address (for branch or for addressing memory). The`as' implementation allows you to use the simpler form ADDRanywhere a PC relative address is called for; the alternate formis supported for compatibility with other assemblers.`#IMM'Immediate dataFile: as.info, Node: SH Floating Point, Next: SH Directives, Prev: SH Syntax, Up: SH-Dependent9.28.3 Floating Point---------------------SH2E, SH3E and SH4 groups have on-chip floating-point unit (FPU). OtherSH groups can use `.float' directive to generate IEEE floating-pointnumbers.SH2E and SH3E support single-precision floating point calculations aswell as entirely PCAPI compatible emulation of double-precisionfloating point calculations. SH2E and SH3E instructions are a subset ofthe floating point calculations conforming to the IEEE754 standard.In addition to single-precision and double-precision floating-pointoperation capability, the on-chip FPU of SH4 has a 128-bit graphicengine that enables 32-bit floating-point data to be processed 128 bitsat a time. It also supports 4 * 4 array operations and inner productoperations. Also, a superscalar architecture is employed that enablessimultaneous execution of two instructions (including FPUinstructions), providing performance of up to twice that ofconventional architectures at the same frequency.File: as.info, Node: SH Directives, Next: SH Opcodes, Prev: SH Floating Point, Up: SH-Dependent9.28.4 SH Machine Directives----------------------------`uaword'`ualong'`as' will issue a warning when a misaligned `.word' or `.long'directive is used. You may use `.uaword' or `.ualong' to indicatethat the value is intentionally misaligned.File: as.info, Node: SH Opcodes, Prev: SH Directives, Up: SH-Dependent9.28.5 Opcodes--------------For detailed information on the SH machine instruction set, see`SH-Microcomputer User's Manual' (Renesas) or `SH-4 32-bit CPU CoreArchitecture' (SuperH) and `SuperH (SH) 64-Bit RISC Series' (SuperH).`as' implements all the standard SH opcodes. No additionalpseudo-instructions are needed on this family. Note, however, thatbecause `as' supports a simpler form of PC-relative addressing, you maysimply write (for example)mov.l bar,r0where other assemblers might require an explicit displacement to `bar'from the program counter:mov.l @(DISP, PC)Here is a summary of SH opcodes:Legend:Rn a numbered registerRm another numbered register#imm immediate datadisp displacementdisp8 8-bit displacementdisp12 12-bit displacementadd #imm,Rn lds.l @Rn+,PRadd Rm,Rn mac.w @Rm+,@Rn+addc Rm,Rn mov #imm,Rnaddv Rm,Rn mov Rm,Rnand #imm,R0 mov.b Rm,@(R0,Rn)and Rm,Rn mov.b Rm,@-Rnand.b #imm,@(R0,GBR) mov.b Rm,@Rnbf disp8 mov.b @(disp,Rm),R0bra disp12 mov.b @(disp,GBR),R0bsr disp12 mov.b @(R0,Rm),Rnbt disp8 mov.b @Rm+,Rnclrmac mov.b @Rm,Rnclrt mov.b R0,@(disp,Rm)cmp/eq #imm,R0 mov.b R0,@(disp,GBR)cmp/eq Rm,Rn mov.l Rm,@(disp,Rn)cmp/ge Rm,Rn mov.l Rm,@(R0,Rn)cmp/gt Rm,Rn mov.l Rm,@-Rncmp/hi Rm,Rn mov.l Rm,@Rncmp/hs Rm,Rn mov.l @(disp,Rn),Rmcmp/pl Rn mov.l @(disp,GBR),R0cmp/pz Rn mov.l @(disp,PC),Rncmp/str Rm,Rn mov.l @(R0,Rm),Rndiv0s Rm,Rn mov.l @Rm+,Rndiv0u mov.l @Rm,Rndiv1 Rm,Rn mov.l R0,@(disp,GBR)exts.b Rm,Rn mov.w Rm,@(R0,Rn)exts.w Rm,Rn mov.w Rm,@-Rnextu.b Rm,Rn mov.w Rm,@Rnextu.w Rm,Rn mov.w @(disp,Rm),R0jmp @Rn mov.w @(disp,GBR),R0jsr @Rn mov.w @(disp,PC),Rnldc Rn,GBR mov.w @(R0,Rm),Rnldc Rn,SR mov.w @Rm+,Rnldc Rn,VBR mov.w @Rm,Rnldc.l @Rn+,GBR mov.w R0,@(disp,Rm)ldc.l @Rn+,SR mov.w R0,@(disp,GBR)ldc.l @Rn+,VBR mova @(disp,PC),R0lds Rn,MACH movt Rnlds Rn,MACL muls Rm,Rnlds Rn,PR mulu Rm,Rnlds.l @Rn+,MACH neg Rm,Rnlds.l @Rn+,MACL negc Rm,Rnnop stc VBR,Rnnot Rm,Rn stc.l GBR,@-Rnor #imm,R0 stc.l SR,@-Rnor Rm,Rn stc.l VBR,@-Rnor.b #imm,@(R0,GBR) sts MACH,Rnrotcl Rn sts MACL,Rnrotcr Rn sts PR,Rnrotl Rn sts.l MACH,@-Rnrotr Rn sts.l MACL,@-Rnrte sts.l PR,@-Rnrts sub Rm,Rnsett subc Rm,Rnshal Rn subv Rm,Rnshar Rn swap.b Rm,Rnshll Rn swap.w Rm,Rnshll16 Rn tas.b @Rnshll2 Rn trapa #immshll8 Rn tst #imm,R0shlr Rn tst Rm,Rnshlr16 Rn tst.b #imm,@(R0,GBR)shlr2 Rn xor #imm,R0shlr8 Rn xor Rm,Rnsleep xor.b #imm,@(R0,GBR)stc GBR,Rn xtrct Rm,Rnstc SR,RnFile: as.info, Node: SH64-Dependent, Next: PDP-11-Dependent, Prev: SH-Dependent, Up: Machine Dependencies9.29 SuperH SH64 Dependent Features===================================* Menu:* SH64 Options:: Options* SH64 Syntax:: Syntax* SH64 Directives:: SH64 Machine Directives* SH64 Opcodes:: OpcodesFile: as.info, Node: SH64 Options, Next: SH64 Syntax, Up: SH64-Dependent9.29.1 Options--------------`-isa=sh4 | sh4a'Specify the sh4 or sh4a instruction set.`-isa=dsp'Enable sh-dsp insns, and disable sh3e / sh4 insns.`-isa=fp'Enable sh2e, sh3e, sh4, and sh4a insn sets.`-isa=all'Enable sh1, sh2, sh2e, sh3, sh3e, sh4, sh4a, and sh-dsp insn sets.`-isa=shmedia | -isa=shcompact'Specify the default instruction set. `SHmedia' specifies the32-bit opcodes, and `SHcompact' specifies the 16-bit opcodescompatible with previous SH families. The default depends on theABI selected; the default for the 64-bit ABI is SHmedia, and thedefault for the 32-bit ABI is SHcompact. If neither the ABI northe ISA is specified, the default is 32-bit SHcompact.Note that the `.mode' pseudo-op is not permitted if the ISA is notspecified on the command line.`-abi=32 | -abi=64'Specify the default ABI. If the ISA is specified and the ABI isnot, the default ABI depends on the ISA, with SHmedia defaultingto 64-bit and SHcompact defaulting to 32-bit.Note that the `.abi' pseudo-op is not permitted if the ABI is notspecified on the command line. When the ABI is specified on thecommand line, any `.abi' pseudo-ops in the source must match it.`-shcompact-const-crange'Emit code-range descriptors for constants in SHcompact codesections.`-no-mix'Disallow SHmedia code in the same section as constants andSHcompact code.`-no-expand'Do not expand MOVI, PT, PTA or PTB instructions.`-expand-pt32'With -abi=64, expand PT, PTA and PTB instructions to 32 bits only.`-h-tick-hex'Support H'00 style hex constants in addition to 0x00 style.File: as.info, Node: SH64 Syntax, Next: SH64 Directives, Prev: SH64 Options, Up: SH64-Dependent9.29.2 Syntax-------------* Menu:* SH64-Chars:: Special Characters* SH64-Regs:: Register Names* SH64-Addressing:: Addressing ModesFile: as.info, Node: SH64-Chars, Next: SH64-Regs, Up: SH64 Syntax9.29.2.1 Special Characters...........................`!' is the line comment character.You can use `;' instead of a newline to separate statements.Since `$' has no special meaning, you may use it in symbol names.File: as.info, Node: SH64-Regs, Next: SH64-Addressing, Prev: SH64-Chars, Up: SH64 Syntax9.29.2.2 Register Names.......................You can use the predefined symbols `r0' through `r63' to refer to theSH64 general registers, `cr0' through `cr63' for control registers,`tr0' through `tr7' for target address registers, `fr0' through `fr63'for single-precision floating point registers, `dr0' through `dr62'(even numbered registers only) for double-precision floating pointregisters, `fv0' through `fv60' (multiples of four only) forsingle-precision floating point vectors, `fp0' through `fp62' (evennumbered registers only) for single-precision floating point pairs,`mtrx0' through `mtrx48' (multiples of 16 only) for 4x4 matrices ofsingle-precision floating point registers, `pc' for the programcounter, and `fpscr' for the floating point status and control register.You can also refer to the control registers by the mnemonics `sr',`ssr', `pssr', `intevt', `expevt', `pexpevt', `tra', `spc', `pspc',`resvec', `vbr', `tea', `dcr', `kcr0', `kcr1', `ctc', and `usr'.File: as.info, Node: SH64-Addressing, Prev: SH64-Regs, Up: SH64 Syntax9.29.2.3 Addressing Modes.........................SH64 operands consist of either a register or immediate value. Theimmediate value can be a constant or label reference (or portion of alabel reference), as in this example:movi 4,r2pt function, tr4movi (function >> 16) & 65535,r0shori function & 65535, r0ld.l r0,4,r0Instruction label references can reference labels in either SHmediaor SHcompact. To differentiate between the two, labels in SHmediasections will always have the least significant bit set (i.e. they willbe odd), which SHcompact labels will have the least significant bitreset (i.e. they will be even). If you need to reference the actualaddress of a label, you can use the `datalabel' modifier, as in thisexample:.long function.long datalabel functionIn that example, the first longword may or may not have the leastsignificant bit set depending on whether the label is an SHmedia labelor an SHcompact label. The second longword will be the actual addressof the label, regardless of what type of label it is.File: as.info, Node: SH64 Directives, Next: SH64 Opcodes, Prev: SH64 Syntax, Up: SH64-Dependent9.29.3 SH64 Machine Directives------------------------------In addition to the SH directives, the SH64 provides the followingdirectives:`.mode [shmedia|shcompact]'`.isa [shmedia|shcompact]'Specify the ISA for the following instructions (the two directivesare equivalent). Note that programs such as `objdump' rely onsymbolic labels to determine when such mode switches occur (bychecking the least significant bit of the label's address), sosuch mode/isa changes should always be followed by a label (inpractice, this is true anyway). Note that you cannot use thesedirectives if you didn't specify an ISA on the command line.`.abi [32|64]'Specify the ABI for the following instructions. Note that youcannot use this directive unless you specified an ABI on thecommand line, and the ABIs specified must match.`.uaquad'Like .uaword and .ualong, this allows you to specify anintentionally unaligned quadword (64 bit word).File: as.info, Node: SH64 Opcodes, Prev: SH64 Directives, Up: SH64-Dependent9.29.4 Opcodes--------------For detailed information on the SH64 machine instruction set, see`SuperH 64 bit RISC Series Architecture Manual' (SuperH, Inc.).`as' implements all the standard SH64 opcodes. In addition, thefollowing pseudo-opcodes may be expanded into one or more alternateopcodes:`movi'If the value doesn't fit into a standard `movi' opcode, `as' willreplace the `movi' with a sequence of `movi' and `shori' opcodes.`pt'This expands to a sequence of `movi' and `shori' opcode, followedby a `ptrel' opcode, or to a `pta' or `ptb' opcode, depending onthe label referenced.File: as.info, Node: Sparc-Dependent, Next: TIC54X-Dependent, Prev: PPC-Dependent, Up: Machine Dependencies9.30 SPARC Dependent Features=============================* Menu:* Sparc-Opts:: Options* Sparc-Aligned-Data:: Option to enforce aligned data* Sparc-Syntax:: Syntax* Sparc-Float:: Floating Point* Sparc-Directives:: Sparc Machine DirectivesFile: as.info, Node: Sparc-Opts, Next: Sparc-Aligned-Data, Up: Sparc-Dependent9.30.1 Options--------------The SPARC chip family includes several successive versions, using thesame core instruction set, but including a few additional instructionsat each version. There are exceptions to this however. For details onwhat instructions each variant supports, please see the chip'sarchitecture reference manual.By default, `as' assumes the core instruction set (SPARC v6), but"bumps" the architecture level as needed: it switches to successivelyhigher architectures as it encounters instructions that only exist inthe higher levels.If not configured for SPARC v9 (`sparc64-*-*') GAS will not bumppast sparclite by default, an option must be passed to enable the v9instructions.GAS treats sparclite as being compatible with v8, unless anarchitecture is explicitly requested. SPARC v9 is always incompatiblewith sparclite.`-Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite'`-Av8plus | -Av8plusa | -Av9 | -Av9a'Use one of the `-A' options to select one of the SPARCarchitectures explicitly. If you select an architectureexplicitly, `as' reports a fatal error if it encounters aninstruction or feature requiring an incompatible or higher level.`-Av8plus' and `-Av8plusa' select a 32 bit environment.`-Av9' and `-Av9a' select a 64 bit environment and are notavailable unless GAS is explicitly configured with 64 bitenvironment support.`-Av8plusa' and `-Av9a' enable the SPARC V9 instruction set withUltraSPARC extensions.`-xarch=v8plus | -xarch=v8plusa'For compatibility with the SunOS v9 assembler. These options areequivalent to -Av8plus and -Av8plusa, respectively.`-bump'Warn whenever it is necessary to switch to another level. If anarchitecture level is explicitly requested, GAS will not issuewarnings until that level is reached, and will then bump the levelas required (except between incompatible levels).`-32 | -64'Select the word size, either 32 bits or 64 bits. These optionsare only available with the ELF object file format, and requirethat the necessary BFD support has been included.File: as.info, Node: Sparc-Aligned-Data, Next: Sparc-Syntax, Prev: Sparc-Opts, Up: Sparc-Dependent9.30.2 Enforcing aligned data-----------------------------SPARC GAS normally permits data to be misaligned. For example, itpermits the `.long' pseudo-op to be used on a byte boundary. However,the native SunOS assemblers issue an error when they see misaligneddata.You can use the `--enforce-aligned-data' option to make SPARC GASalso issue an error about misaligned data, just as the SunOS assemblersdo.The `--enforce-aligned-data' option is not the default because gccissues misaligned data pseudo-ops when it initializes certain packeddata structures (structures defined using the `packed' attribute). Youmay have to assemble with GAS in order to initialize packed datastructures in your own code.File: as.info, Node: Sparc-Syntax, Next: Sparc-Float, Prev: Sparc-Aligned-Data, Up: Sparc-Dependent9.30.3 Sparc Syntax-------------------The assembler syntax closely follows The Sparc Architecture Manual,versions 8 and 9, as well as most extensions defined by Sun for theirUltraSPARC and Niagara line of processors.* Menu:* Sparc-Chars:: Special Characters* Sparc-Regs:: Register Names* Sparc-Constants:: Constant Names* Sparc-Relocs:: Relocations* Sparc-Size-Translations:: Size TranslationsFile: as.info, Node: Sparc-Chars, Next: Sparc-Regs, Up: Sparc-Syntax9.30.3.1 Special Characters...........................`#' is the line comment character.`;' can be used instead of a newline to separate statements.File: as.info, Node: Sparc-Regs, Next: Sparc-Constants, Prev: Sparc-Chars, Up: Sparc-Syntax9.30.3.2 Register Names.......................The Sparc integer register file is broken down into global, outgoing,local, and incoming.* The 8 global registers are referred to as `%gN'.* The 8 outgoing registers are referred to as `%oN'.* The 8 local registers are referred to as `%lN'.* The 8 incoming registers are referred to as `%iN'.* The frame pointer register `%i6' can be referenced using the alias`%fp'.* The stack pointer register `%o6' can be referenced using the alias`%sp'.Floating point registers are simply referred to as `%fN'. Whenassembling for pre-V9, only 32 floating point registers are available.For V9 and later there are 64, but there are restrictions whenreferencing the upper 32 registers. They can only be accessed asdouble or quad, and thus only even or quad numbered accesses areallowed. For example, `%f34' is a legal floating point register, but`%f35' is not.Certain V9 instructions allow access to ancillary state registers.Most simply they can be referred to as `%asrN' where N can be from 16to 31. However, there are some aliases defined to reference ASRregisters defined for various UltraSPARC processors:* The tick compare register is referred to as `%tick_cmpr'.* The system tick register is referred to as `%stick'. An alias,`%sys_tick', exists but is deprecated and should not be used bynew software.* The system tick compare register is referred to as `%stick_cmpr'.An alias, `%sys_tick_cmpr', exists but is deprecated and shouldnot be used by new software.* The software interrupt register is referred to as `%softint'.* The set software interrupt register is referred to as`%set_softint'. The mnemonic `%softint_set' is provided as analias.* The clear software interrupt register is referred to as`%clear_softint'. The mnemonic `%softint_clear' is provided as analias.* The performance instrumentation counters register is referred to as`%pic'.* The performance control register is referred to as `%pcr'.* The graphics status register is referred to as `%gsr'.* The V9 dispatch control register is referred to as `%dcr'.Various V9 branch and conditional move instructions allowspecification of which set of integer condition codes to test. Theseare referred to as `%xcc' and `%icc'.In V9, there are 4 sets of floating point condition codes which arereferred to as `%fccN'.Several special privileged and non-privileged registers exist:* The V9 address space identifier register is referred to as `%asi'.* The V9 restorable windows register is referred to as `%canrestore'.* The V9 savable windows register is referred to as `%cansave'.* The V9 clean windows register is referred to as `%cleanwin'.* The V9 current window pointer register is referred to as `%cwp'.* The floating-point queue register is referred to as `%fq'.* The V8 co-processor queue register is referred to as `%cq'.* The floating point status register is referred to as `%fsr'.* The other windows register is referred to as `%otherwin'.* The V9 program counter register is referred to as `%pc'.* The V9 next program counter register is referred to as `%npc'.* The V9 processor interrupt level register is referred to as `%pil'.* The V9 processor state register is referred to as `%pstate'.* The trap base address register is referred to as `%tba'.* The V9 tick register is referred to as `%tick'.* The V9 trap level is referred to as `%tl'.* The V9 trap program counter is referred to as `%tpc'.* The V9 trap next program counter is referred to as `%tnpc'.* The V9 trap state is referred to as `%tstate'.* The V9 trap type is referred to as `%tt'.* The V9 condition codes is referred to as `%ccr'.* The V9 floating-point registers state is referred to as `%fprs'.* The V9 version register is referred to as `%ver'.* The V9 window state register is referred to as `%wstate'.* The Y register is referred to as `%y'.* The V8 window invalid mask register is referred to as `%wim'.* The V8 processor state register is referred to as `%psr'.* The V9 global register level register is referred to as `%gl'.Several special register names exist for hypervisor mode code:* The hyperprivileged processor state register is referred to as`%hpstate'.* The hyperprivileged trap state register is referred to as`%htstate'.* The hyperprivileged interrupt pending register is referred to as`%hintp'.* The hyperprivileged trap base address register is referred to as`%htba'.* The hyperprivileged implementation version register is referred toas `%hver'.* The hyperprivileged system tick compare register is referred to as`%hstick_cmpr'. Note that there is no `%hstick' register, thenormal `%stick' is used.File: as.info, Node: Sparc-Constants, Next: Sparc-Relocs, Prev: Sparc-Regs, Up: Sparc-Syntax9.30.3.3 Constants..................Several Sparc instructions take an immediate operand field for whichmnemonic names exist. Two such examples are `membar' and `prefetch'.Another example are the set of V9 memory access instruction that allowspecification of an address space identifier.The `membar' instruction specifies a memory barrier that is thedefined by the operand which is a bitmask. The supported maskmnemonics are:* `#Sync' requests that all operations (including nonmemoryreference operations) appearing prior to the `membar' must havebeen performed and the effects of any exceptions become visiblebefore any instructions after the `membar' may be initiated. Thiscorresponds to `membar' cmask field bit 2.* `#MemIssue' requests that all memory reference operationsappearing prior to the `membar' must have been performed beforeany memory operation after the `membar' may be initiated. Thiscorresponds to `membar' cmask field bit 1.* `#Lookaside' requests that a store appearing prior to the `membar'must complete before any load following the `membar' referencingthe same address can be initiated. This corresponds to `membar'cmask field bit 0.* `#StoreStore' defines that the effects of all stores appearingprior to the `membar' instruction must be visible to allprocessors before the effect of any stores following the `membar'.Equivalent to the deprecated `stbar' instruction. Thiscorresponds to `membar' mmask field bit 3.* `#LoadStore' defines all loads appearing prior to the `membar'instruction must have been performed before the effect of anystores following the `membar' is visible to any other processor.This corresponds to `membar' mmask field bit 2.* `#StoreLoad' defines that the effects of all stores appearingprior to the `membar' instruction must be visible to allprocessors before loads following the `membar' may be performed.This corresponds to `membar' mmask field bit 1.* `#LoadLoad' defines that all loads appearing prior to the `membar'instruction must have been performed before any loads followingthe `membar' may be performed. This corresponds to `membar' mmaskfield bit 0.These values can be ored together, for example:membar #Syncmembar #StoreLoad | #LoadLoadmembar #StoreLoad | #StoreStoreThe `prefetch' and `prefetcha' instructions take a prefetch functioncode. The following prefetch function code constant mnemonics areavailable:* `#n_reads' requests a prefetch for several reads, and correspondsto a prefetch function code of 0.`#one_read' requests a prefetch for one read, and corresponds to aprefetch function code of 1.`#n_writes' requests a prefetch for several writes (and possiblyreads), and corresponds to a prefetch function code of 2.`#one_write' requests a prefetch for one write, and corresponds toa prefetch function code of 3.`#page' requests a prefetch page, and corresponds to a prefetchfunction code of 4.`#invalidate' requests a prefetch invalidate, and corresponds to aprefetch function code of 16.`#unified' requests a prefetch to the nearest unified cache, andcorresponds to a prefetch function code of 17.`#n_reads_strong' requests a strong prefetch for several reads,and corresponds to a prefetch function code of 20.`#one_read_strong' requests a strong prefetch for one read, andcorresponds to a prefetch function code of 21.`#n_writes_strong' requests a strong prefetch for several writes,and corresponds to a prefetch function code of 22.`#one_write_strong' requests a strong prefetch for one write, andcorresponds to a prefetch function code of 23.Onle one prefetch code may be specified. Here are some examples:prefetch [%l0 + %l2], #one_readprefetch [%g2 + 8], #n_writesprefetcha [%g1] 0x8, #unifiedprefetcha [%o0 + 0x10] %asi, #n_readsThe actual behavior of a given prefetch function code is processorspecific. If a processor does not implement a given prefetchfunction code, it will treat the prefetch instruction as a nop.For instructions that accept an immediate address space identifier,`as' provides many mnemonics corresponding to V9 defined as wellas UltraSPARC and Niagara extended values. For example, `#ASI_P'and `#ASI_BLK_INIT_QUAD_LDD_AIUS'. See the V9 and processorspecific manuals for details.File: as.info, Node: Sparc-Relocs, Next: Sparc-Size-Translations, Prev: Sparc-Constants, Up: Sparc-Syntax9.30.3.4 Relocations....................ELF relocations are available as defined in the 32-bit and 64-bit SparcELF specifications.`R_SPARC_HI22' is obtained using `%hi' and `R_SPARC_LO10' isobtained using `%lo'. Likewise `R_SPARC_HIX22' is obtained from `%hix'and `R_SPARC_LOX10' is obtained using `%lox'. For example:sethi %hi(symbol), %g1or %g1, %lo(symbol), %g1sethi %hix(symbol), %g1xor %g1, %lox(symbol), %g1These "high" mnemonics extract bits 31:10 of their operand, and the"low" mnemonics extract bits 9:0 of their operand.V9 code model relocations can be requested as follows:* `R_SPARC_HH22' is requested using `%hh'. It can also be generatedusing `%uhi'.* `R_SPARC_HM10' is requested using `%hm'. It can also be generatedusing `%ulo'.* `R_SPARC_LM22' is requested using `%lm'.* `R_SPARC_H44' is requested using `%h44'.* `R_SPARC_M44' is requested using `%m44'.* `R_SPARC_L44' is requested using `%l44'.The PC relative relocation `R_SPARC_PC22' can be obtained byenclosing an operand inside of `%pc22'. Likewise, the `R_SPARC_PC10'relocation can be obtained using `%pc10'. These are mostly used whenassembling PIC code. For example, the standard PIC sequence on Sparcto get the base of the global offset table, PC relative, into aregister, can be performed as:sethi %pc22(_GLOBAL_OFFSET_TABLE_-4), %l7add %l7, %pc10(_GLOBAL_OFFSET_TABLE_+4), %l7Several relocations exist to allow the link editor to potentiallyoptimize GOT data references. The `R_SPARC_GOTDATA_OP_HIX22'relocation can obtained by enclosing an operand inside of`%gdop_hix22'. The `R_SPARC_GOTDATA_OP_LOX10' relocation can obtainedby enclosing an operand inside of `%gdop_lox10'. Likewise,`R_SPARC_GOTDATA_OP' can be obtained by enclosing an operand inside of`%gdop'. For example, assuming the GOT base is in register `%l7':sethi %gdop_hix22(symbol), %l1xor %l1, %gdop_lox10(symbol), %l1ld [%l7 + %l1], %l2, %gdop(symbol)There are many relocations that can be requested for access tothread local storage variables. All of the Sparc TLS mnemonics aresupported:* `R_SPARC_TLS_GD_HI22' is requested using `%tgd_hi22'.* `R_SPARC_TLS_GD_LO10' is requested using `%tgd_lo10'.* `R_SPARC_TLS_GD_ADD' is requested using `%tgd_add'.* `R_SPARC_TLS_GD_CALL' is requested using `%tgd_call'.* `R_SPARC_TLS_LDM_HI22' is requested using `%tldm_hi22'.* `R_SPARC_TLS_LDM_LO10' is requested using `%tldm_lo10'.* `R_SPARC_TLS_LDM_ADD' is requested using `%tldm_add'.* `R_SPARC_TLS_LDM_CALL' is requested using `%tldm_call'.* `R_SPARC_TLS_LDO_HIX22' is requested using `%tldo_hix22'.* `R_SPARC_TLS_LDO_LOX10' is requested using `%tldo_lox10'.* `R_SPARC_TLS_LDO_ADD' is requested using `%tldo_add'.* `R_SPARC_TLS_IE_HI22' is requested using `%tie_hi22'.* `R_SPARC_TLS_IE_LO10' is requested using `%tie_lo10'.* `R_SPARC_TLS_IE_LD' is requested using `%tie_ld'.* `R_SPARC_TLS_IE_LDX' is requested using `%tie_ldx'.* `R_SPARC_TLS_IE_ADD' is requested using `%tie_add'.* `R_SPARC_TLS_LE_HIX22' is requested using `%tle_hix22'.* `R_SPARC_TLS_LE_LOX10' is requested using `%tle_lox10'.Here are some example TLS model sequences.First, General Dynamic:sethi %tgd_hi22(symbol), %l1add %l1, %tgd_lo10(symbol), %l1add %l7, %l1, %o0, %tgd_add(symbol)call __tls_get_addr, %tgd_call(symbol)nopLocal Dynamic:sethi %tldm_hi22(symbol), %l1add %l1, %tldm_lo10(symbol), %l1add %l7, %l1, %o0, %tldm_add(symbol)call __tls_get_addr, %tldm_call(symbol)nopsethi %tldo_hix22(symbol), %l1xor %l1, %tldo_lox10(symbol), %l1add %o0, %l1, %l1, %tldo_add(symbol)Initial Exec:sethi %tie_hi22(symbol), %l1add %l1, %tie_lo10(symbol), %l1ld [%l7 + %l1], %o0, %tie_ld(symbol)add %g7, %o0, %o0, %tie_add(symbol)sethi %tie_hi22(symbol), %l1add %l1, %tie_lo10(symbol), %l1ldx [%l7 + %l1], %o0, %tie_ldx(symbol)add %g7, %o0, %o0, %tie_add(symbol)And finally, Local Exec:sethi %tle_hix22(symbol), %l1add %l1, %tle_lox10(symbol), %l1add %g7, %l1, %l1When assembling for 64-bit, and a secondary constant addend isspecified in an address expression that would normally generate an`R_SPARC_LO10' relocation, the assembler will emit an `R_SPARC_OLO10'instead.File: as.info, Node: Sparc-Size-Translations, Prev: Sparc-Relocs, Up: Sparc-Syntax9.30.3.5 Size Translations..........................Often it is desirable to write code in an operand size agnostic manner.`as' provides support for this via operand size opcode translations.Translations are supported for loads, stores, shifts, compare-and-swapatomics, and the `clr' synthetic instruction.If generating 32-bit code, `as' will generate the 32-bit opcode.Whereas if 64-bit code is being generated, the 64-bit opcode will beemitted. For example `ldn' will be transformed into `ld' for 32-bitcode and `ldx' for 64-bit code.Here is an example meant to demonstrate all the supported opcodetranslations:ldn [%o0], %o1ldna [%o0] %asi, %o2stn %o1, [%o0]stna %o2, [%o0] %asislln %o3, 3, %o3srln %o4, 8, %o4sran %o5, 12, %o5casn [%o0], %o1, %o2casna [%o0] %asi, %o1, %o2clrn %g1In 32-bit mode `as' will emit:ld [%o0], %o1lda [%o0] %asi, %o2st %o1, [%o0]sta %o2, [%o0] %asisll %o3, 3, %o3srl %o4, 8, %o4sra %o5, 12, %o5cas [%o0], %o1, %o2casa [%o0] %asi, %o1, %o2clr %g1And in 64-bit mode `as' will emit:ldx [%o0], %o1ldxa [%o0] %asi, %o2stx %o1, [%o0]stxa %o2, [%o0] %asisllx %o3, 3, %o3srlx %o4, 8, %o4srax %o5, 12, %o5casx [%o0], %o1, %o2casxa [%o0] %asi, %o1, %o2clrx %g1Finally, the `.nword' translating directive is supported as well.It is documented in the section on Sparc machine directives.File: as.info, Node: Sparc-Float, Next: Sparc-Directives, Prev: Sparc-Syntax, Up: Sparc-Dependent9.30.4 Floating Point---------------------The Sparc uses IEEE floating-point numbers.File: as.info, Node: Sparc-Directives, Prev: Sparc-Float, Up: Sparc-Dependent9.30.5 Sparc Machine Directives-------------------------------The Sparc version of `as' supports the following additional machinedirectives:`.align'This must be followed by the desired alignment in bytes.`.common'This must be followed by a symbol name, a positive number, and`"bss"'. This behaves somewhat like `.comm', but the syntax isdifferent.`.half'This is functionally identical to `.short'.`.nword'On the Sparc, the `.nword' directive produces native word sizedvalue, ie. if assembling with -32 it is equivalent to `.word', ifassembling with -64 it is equivalent to `.xword'.`.proc'This directive is ignored. Any text following it on the same lineis also ignored.`.register'This directive declares use of a global application or systemregister. It must be followed by a register name %g2, %g3, %g6 or%g7, comma and the symbol name for that register. If symbol nameis `#scratch', it is a scratch register, if it is `#ignore', itjust suppresses any errors about using undeclared global register,but does not emit any information about it into the object file.This can be useful e.g. if you save the register before use andrestore it after.`.reserve'This must be followed by a symbol name, a positive number, and`"bss"'. This behaves somewhat like `.lcomm', but the syntax isdifferent.`.seg'This must be followed by `"text"', `"data"', or `"data1"'. Itbehaves like `.text', `.data', or `.data 1'.`.skip'This is functionally identical to the `.space' directive.`.word'On the Sparc, the `.word' directive produces 32 bit values,instead of the 16 bit values it produces on many other machines.`.xword'On the Sparc V9 processor, the `.xword' directive produces 64 bitvalues.File: as.info, Node: TIC54X-Dependent, Next: V850-Dependent, Prev: Sparc-Dependent, Up: Machine Dependencies9.31 TIC54X Dependent Features==============================* Menu:* TIC54X-Opts:: Command-line Options* TIC54X-Block:: Blocking* TIC54X-Env:: Environment Settings* TIC54X-Constants:: Constants Syntax* TIC54X-Subsyms:: String Substitution* TIC54X-Locals:: Local Label Syntax* TIC54X-Builtins:: Builtin Assembler Math Functions* TIC54X-Ext:: Extended Addressing Support* TIC54X-Directives:: Directives* TIC54X-Macros:: Macro Features* TIC54X-MMRegs:: Memory-mapped RegistersFile: as.info, Node: TIC54X-Opts, Next: TIC54X-Block, Up: TIC54X-Dependent9.31.1 Options--------------The TMS320C54X version of `as' has a few machine-dependent options.You can use the `-mfar-mode' option to enable extended addressingmode. All addresses will be assumed to be > 16 bits, and theappropriate relocation types will be used. This option is equivalentto using the `.far_mode' directive in the assembly code. If you do notuse the `-mfar-mode' option, all references will be assumed to be 16bits. This option may be abbreviated to `-mf'.You can use the `-mcpu' option to specify a particular CPU. Thisoption is equivalent to using the `.version' directive in the assemblycode. For recognized CPU codes, see *Note `.version':TIC54X-Directives. The default CPU version is `542'.You can use the `-merrors-to-file' option to redirect error outputto a file (this provided for those deficient environments which don'tprovide adequate output redirection). This option may be abbreviated to`-me'.File: as.info, Node: TIC54X-Block, Next: TIC54X-Env, Prev: TIC54X-Opts, Up: TIC54X-Dependent9.31.2 Blocking---------------A blocked section or memory block is guaranteed not to cross theblocking boundary (usually a page, or 128 words) if it is smaller thanthe blocking size, or to start on a page boundary if it is larger thanthe blocking size.File: as.info, Node: TIC54X-Env, Next: TIC54X-Constants, Prev: TIC54X-Block, Up: TIC54X-Dependent9.31.3 Environment Settings---------------------------`C54XDSP_DIR' and `A_DIR' are semicolon-separated paths which are addedto the list of directories normally searched for source and includefiles. `C54XDSP_DIR' will override `A_DIR'.File: as.info, Node: TIC54X-Constants, Next: TIC54X-Subsyms, Prev: TIC54X-Env, Up: TIC54X-Dependent9.31.4 Constants Syntax-----------------------The TIC54X version of `as' allows the following additional constantformats, using a suffix to indicate the radix:Binary `000000B, 011000b'Octal `10Q, 224q'Hexadecimal `45h, 0FH'File: as.info, Node: TIC54X-Subsyms, Next: TIC54X-Locals, Prev: TIC54X-Constants, Up: TIC54X-Dependent9.31.5 String Substitution--------------------------A subset of allowable symbols (which we'll call subsyms) may be assignedarbitrary string values. This is roughly equivalent to C preprocessor#define macros. When `as' encounters one of these symbols, the symbolis replaced in the input stream by its string value. Subsym names*must* begin with a letter.Subsyms may be defined using the `.asg' and `.eval' directives(*Note `.asg': TIC54X-Directives, *Note `.eval': TIC54X-Directives.Expansion is recursive until a previously encountered symbol isseen, at which point substitution stops.In this example, x is replaced with SYM2; SYM2 is replaced withSYM1, and SYM1 is replaced with x. At this point, x has already beenencountered and the substitution stops..asg "x",SYM1.asg "SYM1",SYM2.asg "SYM2",xadd x,a ; final code assembled is "add x, a"Macro parameters are converted to subsyms; a side effect of this isthe normal `as' '\ARG' dereferencing syntax is unnecessary. Subsymsdefined within a macro will have global scope, unless the `.var'directive is used to identify the subsym as a local macro variable*note `.var': TIC54X-Directives.Substitution may be forced in situations where replacement might beambiguous by placing colons on either side of the subsym. The followingcode:.eval "10",xLAB:X: add #x, aWhen assembled becomes:LAB10 add #10, aSmaller parts of the string assigned to a subsym may be accessed withthe following syntax:``:SYMBOL(CHAR_INDEX):''Evaluates to a single-character string, the character atCHAR_INDEX.``:SYMBOL(START,LENGTH):''Evaluates to a substring of SYMBOL beginning at START with lengthLENGTH.File: as.info, Node: TIC54X-Locals, Next: TIC54X-Builtins, Prev: TIC54X-Subsyms, Up: TIC54X-Dependent9.31.6 Local Labels-------------------Local labels may be defined in two ways:* $N, where N is a decimal number between 0 and 9* LABEL?, where LABEL is any legal symbol name.Local labels thus defined may be redefined or automaticallygenerated. The scope of a local label is based on when it may beundefined or reset. This happens when one of the following situationsis encountered:* .newblock directive *note `.newblock': TIC54X-Directives.* The current section is changed (.sect, .text, or .data)* Entering or leaving an included file* The macro scope where the label was defined is exitedFile: as.info, Node: TIC54X-Builtins, Next: TIC54X-Ext, Prev: TIC54X-Locals, Up: TIC54X-Dependent9.31.7 Math Builtins--------------------The following built-in functions may be used to generate afloating-point value. All return a floating-point value except `$cvi',`$int', and `$sgn', which return an integer value.``$acos(EXPR)''Returns the floating point arccosine of EXPR.``$asin(EXPR)''Returns the floating point arcsine of EXPR.``$atan(EXPR)''Returns the floating point arctangent of EXPR.``$atan2(EXPR1,EXPR2)''Returns the floating point arctangent of EXPR1 / EXPR2.``$ceil(EXPR)''Returns the smallest integer not less than EXPR as floating point.``$cosh(EXPR)''Returns the floating point hyperbolic cosine of EXPR.``$cos(EXPR)''Returns the floating point cosine of EXPR.``$cvf(EXPR)''Returns the integer value EXPR converted to floating-point.``$cvi(EXPR)''Returns the floating point value EXPR converted to integer.``$exp(EXPR)''Returns the floating point value e ^ EXPR.``$fabs(EXPR)''Returns the floating point absolute value of EXPR.``$floor(EXPR)''Returns the largest integer that is not greater than EXPR asfloating point.``$fmod(EXPR1,EXPR2)''Returns the floating point remainder of EXPR1 / EXPR2.``$int(EXPR)''Returns 1 if EXPR evaluates to an integer, zero otherwise.``$ldexp(EXPR1,EXPR2)''Returns the floating point value EXPR1 * 2 ^ EXPR2.``$log10(EXPR)''Returns the base 10 logarithm of EXPR.``$log(EXPR)''Returns the natural logarithm of EXPR.``$max(EXPR1,EXPR2)''Returns the floating point maximum of EXPR1 and EXPR2.``$min(EXPR1,EXPR2)''Returns the floating point minimum of EXPR1 and EXPR2.``$pow(EXPR1,EXPR2)''Returns the floating point value EXPR1 ^ EXPR2.``$round(EXPR)''Returns the nearest integer to EXPR as a floating point number.``$sgn(EXPR)''Returns -1, 0, or 1 based on the sign of EXPR.``$sin(EXPR)''Returns the floating point sine of EXPR.``$sinh(EXPR)''Returns the floating point hyperbolic sine of EXPR.``$sqrt(EXPR)''Returns the floating point square root of EXPR.``$tan(EXPR)''Returns the floating point tangent of EXPR.``$tanh(EXPR)''Returns the floating point hyperbolic tangent of EXPR.``$trunc(EXPR)''Returns the integer value of EXPR truncated towards zero asfloating point.File: as.info, Node: TIC54X-Ext, Next: TIC54X-Directives, Prev: TIC54X-Builtins, Up: TIC54X-Dependent9.31.8 Extended Addressing--------------------------The `LDX' pseudo-op is provided for loading the extended addressing bitsof a label or address. For example, if an address `_label' resides inextended program memory, the value of `_label' may be loaded as follows:ldx #_label,16,a ; loads extended bits of _labelor #_label,a ; loads lower 16 bits of _labelbacc a ; full address is in accumulator AFile: as.info, Node: TIC54X-Directives, Next: TIC54X-Macros, Prev: TIC54X-Ext, Up: TIC54X-Dependent9.31.9 Directives-----------------`.align [SIZE]'`.even'Align the section program counter on the next boundary, based onSIZE. SIZE may be any power of 2. `.even' is equivalent to`.align' with a SIZE of 2.`1'Align SPC to word boundary`2'Align SPC to longword boundary (same as .even)`128'Align SPC to page boundary`.asg STRING, NAME'Assign NAME the string STRING. String replacement is performed onSTRING before assignment.`.eval STRING, NAME'Evaluate the contents of string STRING and assign the result as astring to the subsym NAME. String replacement is performed onSTRING before assignment.`.bss SYMBOL, SIZE [, [BLOCKING_FLAG] [,ALIGNMENT_FLAG]]'Reserve space for SYMBOL in the .bss section. SIZE is in words.If present, BLOCKING_FLAG indicates the allocated space should bealigned on a page boundary if it would otherwise cross a pageboundary. If present, ALIGNMENT_FLAG causes the assembler toallocate SIZE on a long word boundary.`.byte VALUE [,...,VALUE_N]'`.ubyte VALUE [,...,VALUE_N]'`.char VALUE [,...,VALUE_N]'`.uchar VALUE [,...,VALUE_N]'Place one or more bytes into consecutive words of the currentsection. The upper 8 bits of each word is zero-filled. If alabel is used, it points to the word allocated for the first byteencountered.`.clink ["SECTION_NAME"]'Set STYP_CLINK flag for this section, which indicates to thelinker that if no symbols from this section are referenced, thesection should not be included in the link. If SECTION_NAME isomitted, the current section is used.`.c_mode'TBD.`.copy "FILENAME" | FILENAME'`.include "FILENAME" | FILENAME'Read source statements from FILENAME. The normal include searchpath is used. Normally .copy will cause statements from theincluded file to be printed in the assembly listing and .includewill not, but this distinction is not currently implemented.`.data'Begin assembling code into the .data section.`.double VALUE [,...,VALUE_N]'`.ldouble VALUE [,...,VALUE_N]'`.float VALUE [,...,VALUE_N]'`.xfloat VALUE [,...,VALUE_N]'Place an IEEE single-precision floating-point representation ofone or more floating-point values into the current section. Allbut `.xfloat' align the result on a longword boundary. Values arestored most-significant word first.`.drlist'`.drnolist'Control printing of directives to the listing file. Ignored.`.emsg STRING'`.mmsg STRING'`.wmsg STRING'Emit a user-defined error, message, or warning, respectively.`.far_mode'Use extended addressing when assembling statements. This shouldappear only once per file, and is equivalent to the -mfar-modeoption *note `-mfar-mode': TIC54X-Opts.`.fclist'`.fcnolist'Control printing of false conditional blocks to the listing file.`.field VALUE [,SIZE]'Initialize a bitfield of SIZE bits in the current section. IfVALUE is relocatable, then SIZE must be 16. SIZE defaults to 16bits. If VALUE does not fit into SIZE bits, the value will betruncated. Successive `.field' directives will pack starting atthe current word, filling the most significant bits first, andaligning to the start of the next word if the field size does notfit into the space remaining in the current word. A `.align'directive with an operand of 1 will force the next `.field'directive to begin packing into a new word. If a label is used, itpoints to the word that contains the specified field.`.global SYMBOL [,...,SYMBOL_N]'`.def SYMBOL [,...,SYMBOL_N]'`.ref SYMBOL [,...,SYMBOL_N]'`.def' nominally identifies a symbol defined in the current fileand available to other files. `.ref' identifies a symbol used inthe current file but defined elsewhere. Both map to the standard`.global' directive.`.half VALUE [,...,VALUE_N]'`.uhalf VALUE [,...,VALUE_N]'`.short VALUE [,...,VALUE_N]'`.ushort VALUE [,...,VALUE_N]'`.int VALUE [,...,VALUE_N]'`.uint VALUE [,...,VALUE_N]'`.word VALUE [,...,VALUE_N]'`.uword VALUE [,...,VALUE_N]'Place one or more values into consecutive words of the currentsection. If a label is used, it points to the word allocated forthe first value encountered.`.label SYMBOL'Define a special SYMBOL to refer to the load time address of thecurrent section program counter.`.length'`.width'Set the page length and width of the output listing file. Ignored.`.list'`.nolist'Control whether the source listing is printed. Ignored.`.long VALUE [,...,VALUE_N]'`.ulong VALUE [,...,VALUE_N]'`.xlong VALUE [,...,VALUE_N]'Place one or more 32-bit values into consecutive words in thecurrent section. The most significant word is stored first.`.long' and `.ulong' align the result on a longword boundary;`xlong' does not.`.loop [COUNT]'`.break [CONDITION]'`.endloop'Repeatedly assemble a block of code. `.loop' begins the block, and`.endloop' marks its termination. COUNT defaults to 1024, andindicates the number of times the block should be repeated.`.break' terminates the loop so that assembly begins after the`.endloop' directive. The optional CONDITION will cause the loopto terminate only if it evaluates to zero.`MACRO_NAME .macro [PARAM1][,...PARAM_N]'`[.mexit]'`.endm'See the section on macros for more explanation (*NoteTIC54X-Macros::.`.mlib "FILENAME" | FILENAME'Load the macro library FILENAME. FILENAME must be an archivedlibrary (BFD ar-compatible) of text files, expected to containonly macro definitions. The standard include search path is used.`.mlist'`.mnolist'Control whether to include macro and loop block expansions in thelisting output. Ignored.`.mmregs'Define global symbolic names for the 'c54x registers. Supposedlyequivalent to executing `.set' directives for each register withits memory-mapped value, but in reality is provided only forcompatibility and does nothing.`.newblock'This directive resets any TIC54X local labels currently defined.Normal `as' local labels are unaffected.`.option OPTION_LIST'Set listing options. Ignored.`.sblock "SECTION_NAME" | SECTION_NAME [,"NAME_N" | NAME_N]'Designate SECTION_NAME for blocking. Blocking guarantees that asection will start on a page boundary (128 words) if it wouldotherwise cross a page boundary. Only initialized sections may bedesignated with this directive. See also *Note TIC54X-Block::.`.sect "SECTION_NAME"'Define a named initialized section and make it the current section.`SYMBOL .set "VALUE"'`SYMBOL .equ "VALUE"'Equate a constant VALUE to a SYMBOL, which is placed in the symboltable. SYMBOL may not be previously defined.`.space SIZE_IN_BITS'`.bes SIZE_IN_BITS'Reserve the given number of bits in the current section andzero-fill them. If a label is used with `.space', it points to the*first* word reserved. With `.bes', the label points to the*last* word reserved.`.sslist'`.ssnolist'Controls the inclusion of subsym replacement in the listingoutput. Ignored.`.string "STRING" [,...,"STRING_N"]'`.pstring "STRING" [,...,"STRING_N"]'Place 8-bit characters from STRING into the current section.`.string' zero-fills the upper 8 bits of each word, while`.pstring' puts two characters into each word, filling themost-significant bits first. Unused space is zero-filled. If alabel is used, it points to the first word initialized.`[STAG] .struct [OFFSET]'`[NAME_1] element [COUNT_1]'`[NAME_2] element [COUNT_2]'`[TNAME] .tag STAGX [TCOUNT]'`...'`[NAME_N] element [COUNT_N]'`[SSIZE] .endstruct'`LABEL .tag [STAG]'Assign symbolic offsets to the elements of a structure. STAGdefines a symbol to use to reference the structure. OFFSETindicates a starting value to use for the first elementencountered; otherwise it defaults to zero. Each element can havea named offset, NAME, which is a symbol assigned the value of theelement's offset into the structure. If STAG is missing, thesebecome global symbols. COUNT adjusts the offset that many times,as if `element' were an array. `element' may be one of `.byte',`.word', `.long', `.float', or any equivalent of those, and thestructure offset is adjusted accordingly. `.field' and `.string'are also allowed; the size of `.field' is one bit, and `.string'is considered to be one word in size. Only element descriptors,structure/union tags, `.align' and conditional assembly directivesare allowed within `.struct'/`.endstruct'. `.align' aligns memberoffsets to word boundaries only. SSIZE, if provided, will alwaysbe assigned the size of the structure.The `.tag' directive, in addition to being used to define astructure/union element within a structure, may be used to apply astructure to a symbol. Once applied to LABEL, the individualstructure elements may be applied to LABEL to produce the desiredoffsets using LABEL as the structure base.`.tab'Set the tab size in the output listing. Ignored.`[UTAG] .union'`[NAME_1] element [COUNT_1]'`[NAME_2] element [COUNT_2]'`[TNAME] .tag UTAGX[,TCOUNT]'`...'`[NAME_N] element [COUNT_N]'`[USIZE] .endstruct'`LABEL .tag [UTAG]'Similar to `.struct', but the offset after each element is reset tozero, and the USIZE is set to the maximum of all defined elements.Starting offset for the union is always zero.`[SYMBOL] .usect "SECTION_NAME", SIZE, [,[BLOCKING_FLAG] [,ALIGNMENT_FLAG]]'Reserve space for variables in a named, uninitialized section(similar to .bss). `.usect' allows definitions sectionsindependent of .bss. SYMBOL points to the first location reservedby this allocation. The symbol may be used as a variable name.SIZE is the allocated size in words. BLOCKING_FLAG indicateswhether to block this section on a page boundary (128 words)(*note TIC54X-Block::). ALIGNMENT FLAG indicates whether thesection should be longword-aligned.`.var SYM[,..., SYM_N]'Define a subsym to be a local variable within a macro. See *NoteTIC54X-Macros::.`.version VERSION'Set which processor to build instructions for. Though thefollowing values are accepted, the op is ignored.`541'`542'`543'`545'`545LP'`546LP'`548'`549'File: as.info, Node: TIC54X-Macros, Next: TIC54X-MMRegs, Prev: TIC54X-Directives, Up: TIC54X-Dependent9.31.10 Macros--------------Macros do not require explicit dereferencing of arguments (i.e., \ARG).During macro expansion, the macro parameters are converted tosubsyms. If the number of arguments passed the macro invocationexceeds the number of parameters defined, the last parameter isassigned the string equivalent of all remaining arguments. If fewerarguments are given than parameters, the missing parameters areassigned empty strings. To include a comma in an argument, you mustenclose the argument in quotes.The following built-in subsym functions allow examination of thestring value of subsyms (or ordinary strings). The arguments arestrings unless otherwise indicated (subsyms passed as args will bereplaced by the strings they represent).``$symlen(STR)''Returns the length of STR.``$symcmp(STR1,STR2)''Returns 0 if STR1 == STR2, non-zero otherwise.``$firstch(STR,CH)''Returns index of the first occurrence of character constant CH inSTR.``$lastch(STR,CH)''Returns index of the last occurrence of character constant CH inSTR.``$isdefed(SYMBOL)''Returns zero if the symbol SYMBOL is not in the symbol table,non-zero otherwise.``$ismember(SYMBOL,LIST)''Assign the first member of comma-separated string LIST to SYMBOL;LIST is reassigned the remainder of the list. Returns zero ifLIST is a null string. Both arguments must be subsyms.``$iscons(EXPR)''Returns 1 if string EXPR is binary, 2 if octal, 3 if hexadecimal,4 if a character, 5 if decimal, and zero if not an integer.``$isname(NAME)''Returns 1 if NAME is a valid symbol name, zero otherwise.``$isreg(REG)''Returns 1 if REG is a valid predefined register name (AR0-AR7only).``$structsz(STAG)''Returns the size of the structure or union represented by STAG.``$structacc(STAG)''Returns the reference point of the structure or union representedby STAG. Always returns zero.File: as.info, Node: TIC54X-MMRegs, Prev: TIC54X-Macros, Up: TIC54X-Dependent9.31.11 Memory-mapped Registers-------------------------------The following symbols are recognized as memory-mapped registers:File: as.info, Node: Z80-Dependent, Next: Z8000-Dependent, Prev: Xtensa-Dependent, Up: Machine Dependencies9.32 Z80 Dependent Features===========================* Menu:* Z80 Options:: Options* Z80 Syntax:: Syntax* Z80 Floating Point:: Floating Point* Z80 Directives:: Z80 Machine Directives* Z80 Opcodes:: OpcodesFile: as.info, Node: Z80 Options, Next: Z80 Syntax, Up: Z80-Dependent9.32.1 Options--------------The Zilog Z80 and Ascii R800 version of `as' have a few machinedependent options.`-z80'Produce code for the Z80 processor. There are additional options torequest warnings and error messages for undocumented instructions.`-ignore-undocumented-instructions'`-Wnud'Silently assemble undocumented Z80-instructions that have beenadopted as documented R800-instructions.`-ignore-unportable-instructions'`-Wnup'Silently assemble all undocumented Z80-instructions.`-warn-undocumented-instructions'`-Wud'Issue warnings for undocumented Z80-instructions that work onR800, do not assemble other undocumented instructions withoutwarning.`-warn-unportable-instructions'`-Wup'Issue warnings for other undocumented Z80-instructions, do nottreat any undocumented instructions as errors.`-forbid-undocumented-instructions'`-Fud'Treat all undocumented z80-instructions as errors.`-forbid-unportable-instructions'`-Fup'Treat undocumented z80-instructions that do not work on R800 aserrors.`-r800'Produce code for the R800 processor. The assembler does not supportundocumented instructions for the R800. In line with commonpractice, `as' uses Z80 instruction names for the R800 processor,as far as they exist.File: as.info, Node: Z80 Syntax, Next: Z80 Floating Point, Prev: Z80 Options, Up: Z80-Dependent9.32.2 Syntax-------------The assembler syntax closely follows the 'Z80 family CPU User Manual' byZilog. In expressions a single `=' may be used as "is equal to"comparison operator.Suffices can be used to indicate the radix of integer constants; `H'or `h' for hexadecimal, `D' or `d' for decimal, `Q', `O', `q' or `o'for octal, and `B' for binary.The suffix `b' denotes a backreference to local label.* Menu:* Z80-Chars:: Special Characters* Z80-Regs:: Register Names* Z80-Case:: Case SensitivityFile: as.info, Node: Z80-Chars, Next: Z80-Regs, Up: Z80 Syntax9.32.2.1 Special Characters...........................The semicolon `;' is the line comment character;The dollar sign `$' can be used as a prefix for hexadecimal numbersand as a symbol denoting the current location counter.A backslash `\' is an ordinary character for the Z80 assembler.The single quote `'' must be followed by a closing quote. If thereis one character in between, it is a character constant, otherwise it isa string constant.File: as.info, Node: Z80-Regs, Next: Z80-Case, Prev: Z80-Chars, Up: Z80 Syntax9.32.2.2 Register Names.......................The registers are referred to with the letters assigned to them byZilog. In addition `as' recognizes `ixl' and `ixh' as the least andmost significant octet in `ix', and similarly `iyl' and `iyh' as partsof `iy'.File: as.info, Node: Z80-Case, Prev: Z80-Regs, Up: Z80 Syntax9.32.2.3 Case Sensitivity.........................Upper and lower case are equivalent in register names, opcodes,condition codes and assembler directives. The case of letters issignificant in labels and symbol names. The case is also important todistinguish the suffix `b' for a backward reference to a local labelfrom the suffix `B' for a number in binary notation.File: as.info, Node: Z80 Floating Point, Next: Z80 Directives, Prev: Z80 Syntax, Up: Z80-Dependent9.32.3 Floating Point---------------------Floating-point numbers are not supported.File: as.info, Node: Z80 Directives, Next: Z80 Opcodes, Prev: Z80 Floating Point, Up: Z80-Dependent9.32.4 Z80 Assembler Directives-------------------------------`as' for the Z80 supports some additional directives for compatibilitywith other assemblers.These are the additional directives in `as' for the Z80:`db EXPRESSION|STRING[,EXPRESSION|STRING...]'`defb EXPRESSION|STRING[,EXPRESSION|STRING...]'For each STRING the characters are copied to the object file, foreach other EXPRESSION the value is stored in one byte. A warningis issued in case of an overflow.`dw EXPRESSION[,EXPRESSION...]'`defw EXPRESSION[,EXPRESSION...]'For each EXPRESSION the value is stored in two bytes, ignoringoverflow.`d24 EXPRESSION[,EXPRESSION...]'`def24 EXPRESSION[,EXPRESSION...]'For each EXPRESSION the value is stored in three bytes, ignoringoverflow.`d32 EXPRESSION[,EXPRESSION...]'`def32 EXPRESSION[,EXPRESSION...]'For each EXPRESSION the value is stored in four bytes, ignoringoverflow.`ds COUNT[, VALUE]'`defs COUNT[, VALUE]'Fill COUNT bytes in the object file with VALUE, if VALUE isomitted it defaults to zero.`SYMBOL equ EXPRESSION'`SYMBOL defl EXPRESSION'These directives set the value of SYMBOL to EXPRESSION. If `equ'is used, it is an error if SYMBOL is already defined. Symbolsdefined with `equ' are not protected from redefinition.`set'This is a normal instruction on Z80, and not an assemblerdirective.`psect NAME'A synonym for *Note Section::, no second argument should be given.File: as.info, Node: Z80 Opcodes, Prev: Z80 Directives, Up: Z80-Dependent9.32.5 Opcodes--------------In line with common practice, Z80 mnemonics are used for both the Z80and the R800.In many instructions it is possible to use one of the half indexregisters (`ixl',`ixh',`iyl',`iyh') in stead of an 8-bit generalpurpose register. This yields instructions that are documented on theR800 and undocumented on the Z80. Similarly `in f,(c)' is documentedon the R800 and undocumented on the Z80.The assembler also supports the following undocumentedZ80-instructions, that have not been adopted in the R800 instructionset:`out (c),0'Sends zero to the port pointed to by register c.`sli M'Equivalent to `M = (M<<1)+1', the operand M can be any operandthat is valid for `sla'. One can use `sll' as a synonym for `sli'.`OP (ix+D), R'This is equivalent told R, (ix+D)OPC Rld (ix+D), RThe operation `OPC' may be any of `res B,', `set B,', `rl', `rlc',`rr', `rrc', `sla', `sli', `sra' and `srl', and the register `R'may be any of `a', `b', `c', `d', `e', `h' and `l'.`OPC (iy+D), R'As above, but with `iy' instead of `ix'.The web site at `http://www.z80.info' is a good starting place tofind more information on programming the Z80.File: as.info, Node: Z8000-Dependent, Next: Vax-Dependent, Prev: Z80-Dependent, Up: Machine Dependencies9.33 Z8000 Dependent Features=============================The Z8000 as supports both members of the Z8000 family: theunsegmented Z8002, with 16 bit addresses, and the segmented Z8001 with24 bit addresses.When the assembler is in unsegmented mode (specified with the`unsegm' directive), an address takes up one word (16 bit) sizedregister. When the assembler is in segmented mode (specified with the`segm' directive), a 24-bit address takes up a long (32 bit) register.*Note Assembler Directives for the Z8000: Z8000 Directives, for a listof other Z8000 specific assembler directives.* Menu:* Z8000 Options:: Command-line options for the Z8000* Z8000 Syntax:: Assembler syntax for the Z8000* Z8000 Directives:: Special directives for the Z8000* Z8000 Opcodes:: OpcodesFile: as.info, Node: Z8000 Options, Next: Z8000 Syntax, Up: Z8000-Dependent9.33.1 Options--------------`-z8001'Generate segmented code by default.`-z8002'Generate unsegmented code by default.File: as.info, Node: Z8000 Syntax, Next: Z8000 Directives, Prev: Z8000 Options, Up: Z8000-Dependent9.33.2 Syntax-------------* Menu:* Z8000-Chars:: Special Characters* Z8000-Regs:: Register Names* Z8000-Addressing:: Addressing ModesFile: as.info, Node: Z8000-Chars, Next: Z8000-Regs, Up: Z8000 Syntax9.33.2.1 Special Characters...........................`!' is the line comment character.You can use `;' instead of a newline to separate statements.File: as.info, Node: Z8000-Regs, Next: Z8000-Addressing, Prev: Z8000-Chars, Up: Z8000 Syntax9.33.2.2 Register Names.......................The Z8000 has sixteen 16 bit registers, numbered 0 to 15. You can referto different sized groups of registers by register number, with theprefix `r' for 16 bit registers, `rr' for 32 bit registers and `rq' for64 bit registers. You can also refer to the contents of the firsteight (of the sixteen 16 bit registers) by bytes. They are named `rlN'and `rhN'._byte registers_rl0 rh0 rl1 rh1 rl2 rh2 rl3 rh3rl4 rh4 rl5 rh5 rl6 rh6 rl7 rh7_word registers_r0 r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11 r12 r13 r14 r15_long word registers_rr0 rr2 rr4 rr6 rr8 rr10 rr12 rr14_quad word registers_rq0 rq4 rq8 rq12File: as.info, Node: Z8000-Addressing, Prev: Z8000-Regs, Up: Z8000 Syntax9.33.2.3 Addressing Modes.........................as understands the following addressing modes for the Z8000:`rlN'`rhN'`rN'`rrN'`rqN'Register direct: 8bit, 16bit, 32bit, and 64bit registers.`@rN'`@rrN'Indirect register: @rrN in segmented mode, @rN in unsegmentedmode.`ADDR'Direct: the 16 bit or 24 bit address (depending on whether theassembler is in segmented or unsegmented mode) of the operand isin the instruction.`address(rN)'Indexed: the 16 or 24 bit address is added to the 16 bit registerto produce the final address in memory of the operand.`rN(#IMM)'`rrN(#IMM)'Base Address: the 16 or 24 bit register is added to the 16 bit signextended immediate displacement to produce the final address inmemory of the operand.`rN(rM)'`rrN(rM)'Base Index: the 16 or 24 bit register rN or rrN is added to thesign extended 16 bit index register rM to produce the finaladdress in memory of the operand.`#XX'Immediate data XX.File: as.info, Node: Z8000 Directives, Next: Z8000 Opcodes, Prev: Z8000 Syntax, Up: Z8000-Dependent9.33.3 Assembler Directives for the Z8000-----------------------------------------The Z8000 port of as includes additional assembler directives, forcompatibility with other Z8000 assemblers. These do not begin with `.'(unlike the ordinary as directives).`segm'`.z8001'Generate code for the segmented Z8001.`unsegm'`.z8002'Generate code for the unsegmented Z8002.`name'Synonym for `.file'`global'Synonym for `.global'`wval'Synonym for `.word'`lval'Synonym for `.long'`bval'Synonym for `.byte'`sval'Assemble a string. `sval' expects one string literal, delimited bysingle quotes. It assembles each byte of the string intoconsecutive addresses. You can use the escape sequence `%XX'(where XX represents a two-digit hexadecimal number) to representthe character whose ASCII value is XX. Use this feature todescribe single quote and other characters that may not appear instring literals as themselves. For example, the C statement`char *a = "he said \"it's 50% off\"";' is represented in Z8000assembly language (shown with the assembler output in hex at theleft) as68652073 sval 'he said %22it%27s 50%25 off%22%00'61696420226974277320353025206F66662200`rsect'synonym for `.section'`block'synonym for `.space'`even'special case of `.align'; aligns output to even byte boundary.File: as.info, Node: Z8000 Opcodes, Prev: Z8000 Directives, Up: Z8000-Dependent9.33.4 Opcodes--------------For detailed information on the Z8000 machine instruction set, see`Z8000 Technical Manual'.The following table summarizes the opcodes and their arguments:rs 16 bit source registerrd 16 bit destination registerrbs 8 bit source registerrbd 8 bit destination registerrrs 32 bit source registerrrd 32 bit destination registerrqs 64 bit source registerrqd 64 bit destination registeraddr 16/24 bit addressimm immediate dataadc rd,rs clrb addr cpsir @rd,@rs,rr,ccadcb rbd,rbs clrb addr(rd) cpsirb @rd,@rs,rr,ccadd rd,@rs clrb rbd dab rbdadd rd,addr com @rd dbjnz rbd,disp7add rd,addr(rs) com addr dec @rd,imm4m1add rd,imm16 com addr(rd) dec addr(rd),imm4m1add rd,rs com rd dec addr,imm4m1addb rbd,@rs comb @rd dec rd,imm4m1addb rbd,addr comb addr decb @rd,imm4m1addb rbd,addr(rs) comb addr(rd) decb addr(rd),imm4m1addb rbd,imm8 comb rbd decb addr,imm4m1addb rbd,rbs comflg flags decb rbd,imm4m1addl rrd,@rs cp @rd,imm16 di i2addl rrd,addr cp addr(rd),imm16 div rrd,@rsaddl rrd,addr(rs) cp addr,imm16 div rrd,addraddl rrd,imm32 cp rd,@rs div rrd,addr(rs)addl rrd,rrs cp rd,addr div rrd,imm16and rd,@rs cp rd,addr(rs) div rrd,rsand rd,addr cp rd,imm16 divl rqd,@rsand rd,addr(rs) cp rd,rs divl rqd,addrand rd,imm16 cpb @rd,imm8 divl rqd,addr(rs)and rd,rs cpb addr(rd),imm8 divl rqd,imm32andb rbd,@rs cpb addr,imm8 divl rqd,rrsandb rbd,addr cpb rbd,@rs djnz rd,disp7andb rbd,addr(rs) cpb rbd,addr ei i2andb rbd,imm8 cpb rbd,addr(rs) ex rd,@rsandb rbd,rbs cpb rbd,imm8 ex rd,addrbit @rd,imm4 cpb rbd,rbs ex rd,addr(rs)bit addr(rd),imm4 cpd rd,@rs,rr,cc ex rd,rsbit addr,imm4 cpdb rbd,@rs,rr,cc exb rbd,@rsbit rd,imm4 cpdr rd,@rs,rr,cc exb rbd,addrbit rd,rs cpdrb rbd,@rs,rr,cc exb rbd,addr(rs)bitb @rd,imm4 cpi rd,@rs,rr,cc exb rbd,rbsbitb addr(rd),imm4 cpib rbd,@rs,rr,cc ext0e imm8bitb addr,imm4 cpir rd,@rs,rr,cc ext0f imm8bitb rbd,imm4 cpirb rbd,@rs,rr,cc ext8e imm8bitb rbd,rs cpl rrd,@rs ext8f imm8bpt cpl rrd,addr exts rrdcall @rd cpl rrd,addr(rs) extsb rdcall addr cpl rrd,imm32 extsl rqdcall addr(rd) cpl rrd,rrs haltcalr disp12 cpsd @rd,@rs,rr,cc in rd,@rsclr @rd cpsdb @rd,@rs,rr,cc in rd,imm16clr addr cpsdr @rd,@rs,rr,cc inb rbd,@rsclr addr(rd) cpsdrb @rd,@rs,rr,cc inb rbd,imm16clr rd cpsi @rd,@rs,rr,cc inc @rd,imm4m1clrb @rd cpsib @rd,@rs,rr,cc inc addr(rd),imm4m1inc addr,imm4m1 ldb rbd,rs(rx) mult rrd,addr(rs)inc rd,imm4m1 ldb rd(imm16),rbs mult rrd,imm16incb @rd,imm4m1 ldb rd(rx),rbs mult rrd,rsincb addr(rd),imm4m1 ldctl ctrl,rs multl rqd,@rsincb addr,imm4m1 ldctl rd,ctrl multl rqd,addrincb rbd,imm4m1 ldd @rs,@rd,rr multl rqd,addr(rs)ind @rd,@rs,ra lddb @rs,@rd,rr multl rqd,imm32indb @rd,@rs,rba lddr @rs,@rd,rr multl rqd,rrsinib @rd,@rs,ra lddrb @rs,@rd,rr neg @rdinibr @rd,@rs,ra ldi @rd,@rs,rr neg addriret ldib @rd,@rs,rr neg addr(rd)jp cc,@rd ldir @rd,@rs,rr neg rdjp cc,addr ldirb @rd,@rs,rr negb @rdjp cc,addr(rd) ldk rd,imm4 negb addrjr cc,disp8 ldl @rd,rrs negb addr(rd)ld @rd,imm16 ldl addr(rd),rrs negb rbdld @rd,rs ldl addr,rrs nopld addr(rd),imm16 ldl rd(imm16),rrs or rd,@rsld addr(rd),rs ldl rd(rx),rrs or rd,addrld addr,imm16 ldl rrd,@rs or rd,addr(rs)ld addr,rs ldl rrd,addr or rd,imm16ld rd(imm16),rs ldl rrd,addr(rs) or rd,rsld rd(rx),rs ldl rrd,imm32 orb rbd,@rsld rd,@rs ldl rrd,rrs orb rbd,addrld rd,addr ldl rrd,rs(imm16) orb rbd,addr(rs)ld rd,addr(rs) ldl rrd,rs(rx) orb rbd,imm8ld rd,imm16 ldm @rd,rs,n orb rbd,rbsld rd,rs ldm addr(rd),rs,n out @rd,rsld rd,rs(imm16) ldm addr,rs,n out imm16,rsld rd,rs(rx) ldm rd,@rs,n outb @rd,rbslda rd,addr ldm rd,addr(rs),n outb imm16,rbslda rd,addr(rs) ldm rd,addr,n outd @rd,@rs,ralda rd,rs(imm16) ldps @rs outdb @rd,@rs,rbalda rd,rs(rx) ldps addr outib @rd,@rs,raldar rd,disp16 ldps addr(rs) outibr @rd,@rs,raldb @rd,imm8 ldr disp16,rs pop @rd,@rsldb @rd,rbs ldr rd,disp16 pop addr(rd),@rsldb addr(rd),imm8 ldrb disp16,rbs pop addr,@rsldb addr(rd),rbs ldrb rbd,disp16 pop rd,@rsldb addr,imm8 ldrl disp16,rrs popl @rd,@rsldb addr,rbs ldrl rrd,disp16 popl addr(rd),@rsldb rbd,@rs mbit popl addr,@rsldb rbd,addr mreq rd popl rrd,@rsldb rbd,addr(rs) mres push @rd,@rsldb rbd,imm8 mset push @rd,addrldb rbd,rbs mult rrd,@rs push @rd,addr(rs)ldb rbd,rs(imm16) mult rrd,addr push @rd,imm16push @rd,rs set addr,imm4 subl rrd,imm32pushl @rd,@rs set rd,imm4 subl rrd,rrspushl @rd,addr set rd,rs tcc cc,rdpushl @rd,addr(rs) setb @rd,imm4 tccb cc,rbdpushl @rd,rrs setb addr(rd),imm4 test @rdres @rd,imm4 setb addr,imm4 test addrres addr(rd),imm4 setb rbd,imm4 test addr(rd)res addr,imm4 setb rbd,rs test rdres rd,imm4 setflg imm4 testb @rdres rd,rs sinb rbd,imm16 testb addrresb @rd,imm4 sinb rd,imm16 testb addr(rd)resb addr(rd),imm4 sind @rd,@rs,ra testb rbdresb addr,imm4 sindb @rd,@rs,rba testl @rdresb rbd,imm4 sinib @rd,@rs,ra testl addrresb rbd,rs sinibr @rd,@rs,ra testl addr(rd)resflg imm4 sla rd,imm8 testl rrdret cc slab rbd,imm8 trdb @rd,@rs,rbarl rd,imm1or2 slal rrd,imm8 trdrb @rd,@rs,rbarlb rbd,imm1or2 sll rd,imm8 trib @rd,@rs,rbrrlc rd,imm1or2 sllb rbd,imm8 trirb @rd,@rs,rbrrlcb rbd,imm1or2 slll rrd,imm8 trtdrb @ra,@rb,rbrrldb rbb,rba sout imm16,rs trtib @ra,@rb,rrrr rd,imm1or2 soutb imm16,rbs trtirb @ra,@rb,rbrrrb rbd,imm1or2 soutd @rd,@rs,ra trtrb @ra,@rb,rbrrrc rd,imm1or2 soutdb @rd,@rs,rba tset @rdrrcb rbd,imm1or2 soutib @rd,@rs,ra tset addrrrdb rbb,rba soutibr @rd,@rs,ra tset addr(rd)rsvd36 sra rd,imm8 tset rdrsvd38 srab rbd,imm8 tsetb @rdrsvd78 sral rrd,imm8 tsetb addrrsvd7e srl rd,imm8 tsetb addr(rd)rsvd9d srlb rbd,imm8 tsetb rbdrsvd9f srll rrd,imm8 xor rd,@rsrsvdb9 sub rd,@rs xor rd,addrrsvdbf sub rd,addr xor rd,addr(rs)sbc rd,rs sub rd,addr(rs) xor rd,imm16sbcb rbd,rbs sub rd,imm16 xor rd,rssc imm8 sub rd,rs xorb rbd,@rssda rd,rs subb rbd,@rs xorb rbd,addrsdab rbd,rs subb rbd,addr xorb rbd,addr(rs)sdal rrd,rs subb rbd,addr(rs) xorb rbd,imm8sdl rd,rs subb rbd,imm8 xorb rbd,rbssdlb rbd,rs subb rbd,rbs xorb rbd,rbssdll rrd,rs subl rrd,@rsset @rd,imm4 subl rrd,addrset addr(rd),imm4 subl rrd,addr(rs)File: as.info, Node: Vax-Dependent, Prev: Z8000-Dependent, Up: Machine Dependencies9.34 VAX Dependent Features===========================* Menu:* VAX-Opts:: VAX Command-Line Options* VAX-float:: VAX Floating Point* VAX-directives:: Vax Machine Directives* VAX-opcodes:: VAX Opcodes* VAX-branch:: VAX Branch Improvement* VAX-operands:: VAX Operands* VAX-no:: Not Supported on VAXFile: as.info, Node: VAX-Opts, Next: VAX-float, Up: Vax-Dependent9.34.1 VAX Command-Line Options-------------------------------The Vax version of `as' accepts any of the following options, gives awarning message that the option was ignored and proceeds. Theseoptions are for compatibility with scripts designed for other people'sassemblers.``-D' (Debug)'``-S' (Symbol Table)'``-T' (Token Trace)'These are obsolete options used to debug old assemblers.``-d' (Displacement size for JUMPs)'This option expects a number following the `-d'. Like optionsthat expect filenames, the number may immediately follow the `-d'(old standard) or constitute the whole of the command lineargument that follows `-d' (GNU standard).``-V' (Virtualize Interpass Temporary File)'Some other assemblers use a temporary file. This option commandedthem to keep the information in active memory rather than in adisk file. `as' always does this, so this option is redundant.``-J' (JUMPify Longer Branches)'Many 32-bit computers permit a variety of branch instructions todo the same job. Some of these instructions are short (and fast)but have a limited range; others are long (and slow) but canbranch anywhere in virtual memory. Often there are 3 flavors ofbranch: short, medium and long. Some other assemblers would emitshort and medium branches, unless told by this option to emitshort and long branches.``-t' (Temporary File Directory)'Some other assemblers may use a temporary file, and this optiontakes a filename being the directory to site the temporary file.Since `as' does not use a temporary disk file, this option makesno difference. `-t' needs exactly one filename.The Vax version of the assembler accepts additional options whencompiled for VMS:`-h N'External symbol or section (used for global variables) names arenot case sensitive on VAX/VMS and always mapped to upper case.This is contrary to the C language definition which explicitlydistinguishes upper and lower case. To implement a standardconforming C compiler, names must be changed (mapped) to preservethe case information. The default mapping is to convert all lowercase characters to uppercase and adding an underscore followed bya 6 digit hex value, representing a 24 digit binary value. Theone digits in the binary value represent which characters areuppercase in the original symbol name.The `-h N' option determines how we map names. This takes severalvalues. No `-h' switch at all allows case hacking as describedabove. A value of zero (`-h0') implies names should be uppercase, and inhibits the case hack. A value of 2 (`-h2') impliesnames should be all lower case, with no case hack. A value of 3(`-h3') implies that case should be preserved. The value 1 isunused. The `-H' option directs `as' to display every mappedsymbol during assembly.Symbols whose names include a dollar sign `$' are exceptions to thegeneral name mapping. These symbols are normally only used toreference VMS library names. Such symbols are always mapped toupper case.`-+'The `-+' option causes `as' to truncate any symbol name largerthan 31 characters. The `-+' option also prevents some codefollowing the `_main' symbol normally added to make the objectfile compatible with Vax-11 "C".`-1'This option is ignored for backward compatibility with `as'version 1.x.`-H'The `-H' option causes `as' to print every symbol which waschanged by case mapping.File: as.info, Node: VAX-float, Next: VAX-directives, Prev: VAX-Opts, Up: Vax-Dependent9.34.2 VAX Floating Point-------------------------Conversion of flonums to floating point is correct, and compatible withprevious assemblers. Rounding is towards zero if the remainder isexactly half the least significant bit.`D', `F', `G' and `H' floating point formats are understood.Immediate floating literals (_e.g._ `S`$6.9') are renderedcorrectly. Again, rounding is towards zero in the boundary case.The `.float' directive produces `f' format numbers. The `.double'directive produces `d' format numbers.File: as.info, Node: VAX-directives, Next: VAX-opcodes, Prev: VAX-float, Up: Vax-Dependent9.34.3 Vax Machine Directives-----------------------------The Vax version of the assembler supports four directives forgenerating Vax floating point constants. They are described in thetable below.`.dfloat'This expects zero or more flonums, separated by commas, andassembles Vax `d' format 64-bit floating point constants.`.ffloat'This expects zero or more flonums, separated by commas, andassembles Vax `f' format 32-bit floating point constants.`.gfloat'This expects zero or more flonums, separated by commas, andassembles Vax `g' format 64-bit floating point constants.`.hfloat'This expects zero or more flonums, separated by commas, andassembles Vax `h' format 128-bit floating point constants.File: as.info, Node: VAX-opcodes, Next: VAX-branch, Prev: VAX-directives, Up: Vax-Dependent9.34.4 VAX Opcodes------------------All DEC mnemonics are supported. Beware that `case...' instructionshave exactly 3 operands. The dispatch table that follows the `case...'instruction should be made with `.word' statements. This is compatiblewith all unix assemblers we know of.File: as.info, Node: VAX-branch, Next: VAX-operands, Prev: VAX-opcodes, Up: Vax-Dependent9.34.5 VAX Branch Improvement-----------------------------Certain pseudo opcodes are permitted. They are for branchinstructions. They expand to the shortest branch instruction thatreaches the target. Generally these mnemonics are made by substituting`j' for `b' at the start of a DEC mnemonic. This feature is includedboth for compatibility and to help compilers. If you do not need thisfeature, avoid these opcodes. Here are the mnemonics, and the codethey can expand into.`jbsb'`Jsb' is already an instruction mnemonic, so we chose `jbsb'.(byte displacement)`bsbb ...'(word displacement)`bsbw ...'(long displacement)`jsb ...'`jbr'`jr'Unconditional branch.(byte displacement)`brb ...'(word displacement)`brw ...'(long displacement)`jmp ...'`jCOND'COND may be any one of the conditional branches `neq', `nequ',`eql', `eqlu', `gtr', `geq', `lss', `gtru', `lequ', `vc', `vs',`gequ', `cc', `lssu', `cs'. COND may also be one of the bit tests`bs', `bc', `bss', `bcs', `bsc', `bcc', `bssi', `bcci', `lbs',`lbc'. NOTCOND is the opposite condition to COND.(byte displacement)`bCOND ...'(word displacement)`bNOTCOND foo ; brw ... ; foo:'(long displacement)`bNOTCOND foo ; jmp ... ; foo:'`jacbX'X may be one of `b d f g h l w'.(word displacement)`OPCODE ...'(long displacement)OPCODE ..., foo ;brb bar ;foo: jmp ... ;bar:`jaobYYY'YYY may be one of `lss leq'.`jsobZZZ'ZZZ may be one of `geq gtr'.(byte displacement)`OPCODE ...'(word displacement)OPCODE ..., foo ;brb bar ;foo: brw DESTINATION ;bar:(long displacement)OPCODE ..., foo ;brb bar ;foo: jmp DESTINATION ;bar:`aobleq'`aoblss'`sobgeq'`sobgtr'(byte displacement)`OPCODE ...'(word displacement)OPCODE ..., foo ;brb bar ;foo: brw DESTINATION ;bar:(long displacement)OPCODE ..., foo ;brb bar ;foo: jmp DESTINATION ;bar:File: as.info, Node: VAX-operands, Next: VAX-no, Prev: VAX-branch, Up: Vax-Dependent9.34.6 VAX Operands-------------------The immediate character is `$' for Unix compatibility, not `#' as DECwrites it.The indirect character is `*' for Unix compatibility, not `@' as DECwrites it.The displacement sizing character is ``' (an accent grave) for Unixcompatibility, not `^' as DEC writes it. The letter preceding ``' mayhave either case. `G' is not understood, but all other letters (`b i ls w') are understood.Register names understood are `r0 r1 r2 ... r15 ap fp sp pc'. Upperand lower case letters are equivalent.For instancetstb *w`$4(r5)Any expression is permitted in an operand. Operands are commaseparated.File: as.info, Node: VAX-no, Prev: VAX-operands, Up: Vax-Dependent9.34.7 Not Supported on VAX---------------------------Vax bit fields can not be assembled with `as'. Someone can add therequired code if they really need it.File: as.info, Node: V850-Dependent, Next: Xtensa-Dependent, Prev: TIC54X-Dependent, Up: Machine Dependencies9.35 v850 Dependent Features============================* Menu:* V850 Options:: Options* V850 Syntax:: Syntax* V850 Floating Point:: Floating Point* V850 Directives:: V850 Machine Directives* V850 Opcodes:: OpcodesFile: as.info, Node: V850 Options, Next: V850 Syntax, Up: V850-Dependent9.35.1 Options--------------`as' supports the following additional command-line options for theV850 processor family:`-wsigned_overflow'Causes warnings to be produced when signed immediate valuesoverflow the space available for then within their opcodes. Bydefault this option is disabled as it is possible to receivespurious warnings due to using exact bit patterns as immediateconstants.`-wunsigned_overflow'Causes warnings to be produced when unsigned immediate valuesoverflow the space available for then within their opcodes. Bydefault this option is disabled as it is possible to receivespurious warnings due to using exact bit patterns as immediateconstants.`-mv850'Specifies that the assembled code should be marked as beingtargeted at the V850 processor. This allows the linker to detectattempts to link such code with code assembled for otherprocessors.`-mv850e'Specifies that the assembled code should be marked as beingtargeted at the V850E processor. This allows the linker to detectattempts to link such code with code assembled for otherprocessors.`-mv850e1'Specifies that the assembled code should be marked as beingtargeted at the V850E1 processor. This allows the linker todetect attempts to link such code with code assembled for otherprocessors.`-mv850any'Specifies that the assembled code should be marked as beingtargeted at the V850 processor but support instructions that arespecific to the extended variants of the process. This allows theproduction of binaries that contain target specific code, butwhich are also intended to be used in a generic fashion. Forexample libgcc.a contains generic routines used by the codeproduced by GCC for all versions of the v850 architecture,together with support routines only used by the V850E architecture.`-mrelax'Enables relaxation. This allows the .longcall and .longjump pseudoops to be used in the assembler source code. These ops labelsections of code which are either a long function call or a longbranch. The assembler will then flag these sections of code andthe linker will attempt to relax them.File: as.info, Node: V850 Syntax, Next: V850 Floating Point, Prev: V850 Options, Up: V850-Dependent9.35.2 Syntax-------------* Menu:* V850-Chars:: Special Characters* V850-Regs:: Register NamesFile: as.info, Node: V850-Chars, Next: V850-Regs, Up: V850 Syntax9.35.2.1 Special Characters...........................`#' is the line comment character.File: as.info, Node: V850-Regs, Prev: V850-Chars, Up: V850 Syntax9.35.2.2 Register Names.......................`as' supports the following names for registers:`general register 0'r0, zero`general register 1'r1`general register 2'r2, hp`general register 3'r3, sp`general register 4'r4, gp`general register 5'r5, tp`general register 6'r6`general register 7'r7`general register 8'r8`general register 9'r9`general register 10'r10`general register 11'r11`general register 12'r12`general register 13'r13`general register 14'r14`general register 15'r15`general register 16'r16`general register 17'r17`general register 18'r18`general register 19'r19`general register 20'r20`general register 21'r21`general register 22'r22`general register 23'r23`general register 24'r24`general register 25'r25`general register 26'r26`general register 27'r27`general register 28'r28`general register 29'r29`general register 30'r30, ep`general register 31'r31, lp`system register 0'eipc`system register 1'eipsw`system register 2'fepc`system register 3'fepsw`system register 4'ecr`system register 5'psw`system register 16'ctpc`system register 17'ctpsw`system register 18'dbpc`system register 19'dbpsw`system register 20'ctbpFile: as.info, Node: V850 Floating Point, Next: V850 Directives, Prev: V850 Syntax, Up: V850-Dependent9.35.3 Floating Point---------------------The V850 family uses IEEE floating-point numbers.File: as.info, Node: V850 Directives, Next: V850 Opcodes, Prev: V850 Floating Point, Up: V850-Dependent9.35.4 V850 Machine Directives------------------------------`.offset <EXPRESSION>'Moves the offset into the current section to the specified amount.`.section "name", <type>'This is an extension to the standard .section directive. It setsthe current section to be <type> and creates an alias for thissection called "name".`.v850'Specifies that the assembled code should be marked as beingtargeted at the V850 processor. This allows the linker to detectattempts to link such code with code assembled for otherprocessors.`.v850e'Specifies that the assembled code should be marked as beingtargeted at the V850E processor. This allows the linker to detectattempts to link such code with code assembled for otherprocessors.`.v850e1'Specifies that the assembled code should be marked as beingtargeted at the V850E1 processor. This allows the linker todetect attempts to link such code with code assembled for otherprocessors.File: as.info, Node: V850 Opcodes, Prev: V850 Directives, Up: V850-Dependent9.35.5 Opcodes--------------`as' implements all the standard V850 opcodes.`as' also implements the following pseudo ops:`hi0()'Computes the higher 16 bits of the given expression and stores itinto the immediate operand field of the given instruction. Forexample:`mulhi hi0(here - there), r5, r6'computes the difference between the address of labels 'here' and'there', takes the upper 16 bits of this difference, shifts itdown 16 bits and then multiplies it by the lower 16 bits inregister 5, putting the result into register 6.`lo()'Computes the lower 16 bits of the given expression and stores itinto the immediate operand field of the given instruction. Forexample:`addi lo(here - there), r5, r6'computes the difference between the address of labels 'here' and'there', takes the lower 16 bits of this difference and adds it toregister 5, putting the result into register 6.`hi()'Computes the higher 16 bits of the given expression and then addsthe value of the most significant bit of the lower 16 bits of theexpression and stores the result into the immediate operand fieldof the given instruction. For example the following code can beused to compute the address of the label 'here' and store it intoregister 6:`movhi hi(here), r0, r6' `movea lo(here), r6, r6'The reason for this special behaviour is that movea performs a signextension on its immediate operand. So for example if the addressof 'here' was 0xFFFFFFFF then without the special behaviour of thehi() pseudo-op the movhi instruction would put 0xFFFF0000 into r6,then the movea instruction would takes its immediate operand,0xFFFF, sign extend it to 32 bits, 0xFFFFFFFF, and then add itinto r6 giving 0xFFFEFFFF which is wrong (the fifth nibble is E).With the hi() pseudo op adding in the top bit of the lo() pseudoop, the movhi instruction actually stores 0 into r6 (0xFFFF + 1 =0x0000), so that the movea instruction stores 0xFFFFFFFF into r6 -the right value.`hilo()'Computes the 32 bit value of the given expression and stores itinto the immediate operand field of the given instruction (whichmust be a mov instruction). For example:`mov hilo(here), r6'computes the absolute address of label 'here' and puts the resultinto register 6.`sdaoff()'Computes the offset of the named variable from the start of theSmall Data Area (whoes address is held in register 4, the GPregister) and stores the result as a 16 bit signed value in theimmediate operand field of the given instruction. For example:`ld.w sdaoff(_a_variable)[gp],r6'loads the contents of the location pointed to by the label'_a_variable' into register 6, provided that the label is locatedsomewhere within +/- 32K of the address held in the GP register.[Note the linker assumes that the GP register contains a fixedaddress set to the address of the label called '__gp'. This caneither be set up automatically by the linker, or specifically setby using the `--defsym __gp=<value>' command line option].`tdaoff()'Computes the offset of the named variable from the start of theTiny Data Area (whoes address is held in register 30, the EPregister) and stores the result as a 4,5, 7 or 8 bit unsignedvalue in the immediate operand field of the given instruction.For example:`sld.w tdaoff(_a_variable)[ep],r6'loads the contents of the location pointed to by the label'_a_variable' into register 6, provided that the label is locatedsomewhere within +256 bytes of the address held in the EPregister. [Note the linker assumes that the EP register containsa fixed address set to the address of the label called '__ep'.This can either be set up automatically by the linker, orspecifically set by using the `--defsym __ep=<value>' command lineoption].`zdaoff()'Computes the offset of the named variable from address 0 andstores the result as a 16 bit signed value in the immediateoperand field of the given instruction. For example:`movea zdaoff(_a_variable),zero,r6'puts the address of the label '_a_variable' into register 6,assuming that the label is somewhere within the first 32K ofmemory. (Strictly speaking it also possible to access the last32K of memory as well, as the offsets are signed).`ctoff()'Computes the offset of the named variable from the start of theCall Table Area (whoes address is helg in system register 20, theCTBP register) and stores the result a 6 or 16 bit unsigned valuein the immediate field of then given instruction or piece of data.For example:`callt ctoff(table_func1)'will put the call the function whoes address is held in the calltable at the location labeled 'table_func1'.`.longcall `name''Indicates that the following sequence of instructions is a longcall to function `name'. The linker will attempt to shorten thiscall sequence if `name' is within a 22bit offset of the call. Onlyvalid if the `-mrelax' command line switch has been enabled.`.longjump `name''Indicates that the following sequence of instructions is a longjump to label `name'. The linker will attempt to shorten this codesequence if `name' is within a 22bit offset of the jump. Onlyvalid if the `-mrelax' command line switch has been enabled.For information on the V850 instruction set, see `V850 Family32-/16-Bit single-Chip Microcontroller Architecture Manual' from NEC.Ltd.File: as.info, Node: Xtensa-Dependent, Next: Z80-Dependent, Prev: V850-Dependent, Up: Machine Dependencies9.36 Xtensa Dependent Features==============================This chapter covers features of the GNU assembler that are specificto the Xtensa architecture. For details about the Xtensa instructionset, please consult the `Xtensa Instruction Set Architecture (ISA)Reference Manual'.* Menu:* Xtensa Options:: Command-line Options.* Xtensa Syntax:: Assembler Syntax for Xtensa Processors.* Xtensa Optimizations:: Assembler Optimizations.* Xtensa Relaxation:: Other Automatic Transformations.* Xtensa Directives:: Directives for Xtensa Processors.File: as.info, Node: Xtensa Options, Next: Xtensa Syntax, Up: Xtensa-Dependent9.36.1 Command Line Options---------------------------The Xtensa version of the GNU assembler supports these special options:`--text-section-literals | --no-text-section-literals'Control the treatment of literal pools. The default is`--no-text-section-literals', which places literals in separatesections in the output file. This allows the literal pool to beplaced in a data RAM/ROM. With `--text-section-literals', theliterals are interspersed in the text section in order to keepthem as close as possible to their references. This may benecessary for large assembly files, where the literals wouldotherwise be out of range of the `L32R' instructions in the textsection. These options only affect literals referenced viaPC-relative `L32R' instructions; literals for absolute mode `L32R'instructions are handled separately. *Note literal: LiteralDirective.`--absolute-literals | --no-absolute-literals'Indicate to the assembler whether `L32R' instructions use absoluteor PC-relative addressing. If the processor includes the absoluteaddressing option, the default is to use absolute `L32R'relocations. Otherwise, only the PC-relative `L32R' relocationscan be used.`--target-align | --no-target-align'Enable or disable automatic alignment to reduce branch penaltiesat some expense in code size. *Note Automatic InstructionAlignment: Xtensa Automatic Alignment. This optimization isenabled by default. Note that the assembler will always aligninstructions like `LOOP' that have fixed alignment requirements.`--longcalls | --no-longcalls'Enable or disable transformation of call instructions to allowcalls across a greater range of addresses. *Note Function CallRelaxation: Xtensa Call Relaxation. This option should be usedwhen call targets can potentially be out of range. It may degradeboth code size and performance, but the linker can generallyoptimize away the unnecessary overhead when a call ends up withinrange. The default is `--no-longcalls'.`--transform | --no-transform'Enable or disable all assembler transformations of Xtensainstructions, including both relaxation and optimization. Thedefault is `--transform'; `--no-transform' should only be used inthe rare cases when the instructions must be exactly as specifiedin the assembly source. Using `--no-transform' causes out of rangeinstruction operands to be errors.`--rename-section OLDNAME=NEWNAME'Rename the OLDNAME section to NEWNAME. This option can be usedmultiple times to rename multiple sections.File: as.info, Node: Xtensa Syntax, Next: Xtensa Optimizations, Prev: Xtensa Options, Up: Xtensa-Dependent9.36.2 Assembler Syntax-----------------------Block comments are delimited by `/*' and `*/'. End of line commentsmay be introduced with either `#' or `//'.Instructions consist of a leading opcode or macro name followed bywhitespace and an optional comma-separated list of operands:OPCODE [OPERAND, ...]Instructions must be separated by a newline or semicolon.FLIX instructions, which bundle multiple opcodes together in a singleinstruction, are specified by enclosing the bundled opcodes insidebraces:{[FORMAT]OPCODE0 [OPERANDS]OPCODE1 [OPERANDS]OPCODE2 [OPERANDS]...}The opcodes in a FLIX instruction are listed in the same order as thecorresponding instruction slots in the TIE format declaration.Directives and labels are not allowed inside the braces of a FLIXinstruction. A particular TIE format name can optionally be specifiedimmediately after the opening brace, but this is usually unnecessary.The assembler will automatically search for a format that can encode thespecified opcodes, so the format name need only be specified in rarecases where there is more than one applicable format and where itmatters which of those formats is used. A FLIX instruction can also bespecified on a single line by separating the opcodes with semicolons:{ [FORMAT;] OPCODE0 [OPERANDS]; OPCODE1 [OPERANDS]; OPCODE2 [OPERANDS]; ... }If an opcode can only be encoded in a FLIX instruction but is notspecified as part of a FLIX bundle, the assembler will choose thesmallest format where the opcode can be encoded and will fill unusedinstruction slots with no-ops.* Menu:* Xtensa Opcodes:: Opcode Naming Conventions.* Xtensa Registers:: Register Naming.File: as.info, Node: Xtensa Opcodes, Next: Xtensa Registers, Up: Xtensa Syntax9.36.2.1 Opcode Names.....................See the `Xtensa Instruction Set Architecture (ISA) Reference Manual'for a complete list of opcodes and descriptions of their semantics.If an opcode name is prefixed with an underscore character (`_'),`as' will not transform that instruction in any way. The underscoreprefix disables both optimization (*note Xtensa Optimizations: XtensaOptimizations.) and relaxation (*note Xtensa Relaxation: XtensaRelaxation.) for that particular instruction. Only use the underscoreprefix when it is essential to select the exact opcode produced by theassembler. Using this feature unnecessarily makes the code lessefficient by disabling assembler optimization and less flexible bydisabling relaxation.Note that this special handling of underscore prefixes only appliesto Xtensa opcodes, not to either built-in macros or user-defined macros.When an underscore prefix is used with a macro (e.g., `_MOV'), itrefers to a different macro. The assembler generally provides built-inmacros both with and without the underscore prefix, where the underscoreversions behave as if the underscore carries through to the instructionsin the macros. For example, `_MOV' may expand to `_MOV.N'.The underscore prefix only applies to individual instructions, not toseries of instructions. For example, if a series of instructions haveunderscore prefixes, the assembler will not transform the individualinstructions, but it may insert other instructions between them (e.g.,to align a `LOOP' instruction). To prevent the assembler frommodifying a series of instructions as a whole, use the `no-transform'directive. *Note transform: Transform Directive.File: as.info, Node: Xtensa Registers, Prev: Xtensa Opcodes, Up: Xtensa Syntax9.36.2.2 Register Names.......................The assembly syntax for a register file entry is the "short" name for aTIE register file followed by the index into that register file. Forexample, the general-purpose `AR' register file has a short name of`a', so these registers are named `a0'...`a15'. As a special feature,`sp' is also supported as a synonym for `a1'. Additional registers maybe added by processor configuration options and by designer-defined TIEextensions. An initial `$' character is optional in all register names.File: as.info, Node: Xtensa Optimizations, Next: Xtensa Relaxation, Prev: Xtensa Syntax, Up: Xtensa-Dependent9.36.3 Xtensa Optimizations---------------------------The optimizations currently supported by `as' are generation of densityinstructions where appropriate and automatic branch target alignment.* Menu:* Density Instructions:: Using Density Instructions.* Xtensa Automatic Alignment:: Automatic Instruction Alignment.File: as.info, Node: Density Instructions, Next: Xtensa Automatic Alignment, Up: Xtensa Optimizations9.36.3.1 Using Density Instructions...................................The Xtensa instruction set has a code density option that provides16-bit versions of some of the most commonly used opcodes. Use of theseopcodes can significantly reduce code size. When possible, theassembler automatically translates instructions from the core Xtensainstruction set into equivalent instructions from the Xtensa codedensity option. This translation can be disabled by using underscoreprefixes (*note Opcode Names: Xtensa Opcodes.), by using the`--no-transform' command-line option (*note Command Line Options:Xtensa Options.), or by using the `no-transform' directive (*notetransform: Transform Directive.).It is a good idea _not_ to use the density instructions directly.The assembler will automatically select dense instructions wherepossible. If you later need to use an Xtensa processor without the codedensity option, the same assembly code will then work withoutmodification.File: as.info, Node: Xtensa Automatic Alignment, Prev: Density Instructions, Up: Xtensa Optimizations9.36.3.2 Automatic Instruction Alignment........................................The Xtensa assembler will automatically align certain instructions, bothto optimize performance and to satisfy architectural requirements.As an optimization to improve performance, the assembler attempts toalign branch targets so they do not cross instruction fetch boundaries.(Xtensa processors can be configured with either 32-bit or 64-bitinstruction fetch widths.) An instruction immediately following a callis treated as a branch target in this context, because it will be thetarget of a return from the call. This alignment has the potential toreduce branch penalties at some expense in code size. Thisoptimization is enabled by default. You can disable it with the`--no-target-align' command-line option (*note Command Line Options:Xtensa Options.).The target alignment optimization is done without adding instructionsthat could increase the execution time of the program. If there aredensity instructions in the code preceding a target, the assembler canchange the target alignment by widening some of those instructions tothe equivalent 24-bit instructions. Extra bytes of padding can beinserted immediately following unconditional jump and returninstructions. This approach is usually successful in aligning many,but not all, branch targets.The `LOOP' family of instructions must be aligned such that thefirst instruction in the loop body does not cross an instruction fetchboundary (e.g., with a 32-bit fetch width, a `LOOP' instruction must beon either a 1 or 2 mod 4 byte boundary). The assembler knows aboutthis restriction and inserts the minimal number of 2 or 3 byte no-opinstructions to satisfy it. When no-op instructions are added, anylabel immediately preceding the original loop will be moved in order torefer to the loop instruction, not the newly generated no-opinstruction. To preserve binary compatibility across processors withdifferent fetch widths, the assembler conservatively assumes a 32-bitfetch width when aligning `LOOP' instructions (except if the firstinstruction in the loop is a 64-bit instruction).Previous versions of the assembler automatically aligned `ENTRY'instructions to 4-byte boundaries, but that alignment is now theprogrammer's responsibility.File: as.info, Node: Xtensa Relaxation, Next: Xtensa Directives, Prev: Xtensa Optimizations, Up: Xtensa-Dependent9.36.4 Xtensa Relaxation------------------------When an instruction operand is outside the range allowed for thatparticular instruction field, `as' can transform the code to use afunctionally-equivalent instruction or sequence of instructions. Thisprocess is known as "relaxation". This is typically done for branchinstructions because the distance of the branch targets is not knownuntil assembly-time. The Xtensa assembler offers branch relaxation andalso extends this concept to function calls, `MOVI' instructions andother instructions with immediate fields.* Menu:* Xtensa Branch Relaxation:: Relaxation of Branches.* Xtensa Call Relaxation:: Relaxation of Function Calls.* Xtensa Immediate Relaxation:: Relaxation of other Immediate Fields.File: as.info, Node: Xtensa Branch Relaxation, Next: Xtensa Call Relaxation, Up: Xtensa Relaxation9.36.4.1 Conditional Branch Relaxation......................................When the target of a branch is too far away from the branch itself,i.e., when the offset from the branch to the target is too large to fitin the immediate field of the branch instruction, it may be necessary toreplace the branch with a branch around a jump. For example,beqz a2, Lmay result in:bnez.n a2, Mj LM:(The `BNEZ.N' instruction would be used in this example only if thedensity option is available. Otherwise, `BNEZ' would be used.)This relaxation works well because the unconditional jump instructionhas a much larger offset range than the various conditional branches.However, an error will occur if a branch target is beyond the range of ajump instruction. `as' cannot relax unconditional jumps. Similarly,an error will occur if the original input contains an unconditionaljump to a target that is out of range.Branch relaxation is enabled by default. It can be disabled by usingunderscore prefixes (*note Opcode Names: Xtensa Opcodes.), the`--no-transform' command-line option (*note Command Line Options:Xtensa Options.), or the `no-transform' directive (*note transform:Transform Directive.).File: as.info, Node: Xtensa Call Relaxation, Next: Xtensa Immediate Relaxation, Prev: Xtensa Branch Relaxation, Up: Xtensa Relaxation9.36.4.2 Function Call Relaxation.................................Function calls may require relaxation because the Xtensa immediate callinstructions (`CALL0', `CALL4', `CALL8' and `CALL12') provide aPC-relative offset of only 512 Kbytes in either direction. For largerprograms, it may be necessary to use indirect calls (`CALLX0',`CALLX4', `CALLX8' and `CALLX12') where the target address is specifiedin a register. The Xtensa assembler can automatically relax immediatecall instructions into indirect call instructions. This relaxation isdone by loading the address of the called function into the callee'sreturn address register and then using a `CALLX' instruction. So, forexample:call8 funcmight be relaxed to:.literal .L1, funcl32r a8, .L1callx8 a8Because the addresses of targets of function calls are not generallyknown until link-time, the assembler must assume the worst and relax allthe calls to functions in other source files, not just those that reallywill be out of range. The linker can recognize calls that wereunnecessarily relaxed, and it will remove the overhead introduced by theassembler for those cases where direct calls are sufficient.Call relaxation is disabled by default because it can have a negativeeffect on both code size and performance, although the linker canusually eliminate the unnecessary overhead. If a program is too largeand some of the calls are out of range, function call relaxation can beenabled using the `--longcalls' command-line option or the `longcalls'directive (*note longcalls: Longcalls Directive.).File: as.info, Node: Xtensa Immediate Relaxation, Prev: Xtensa Call Relaxation, Up: Xtensa Relaxation9.36.4.3 Other Immediate Field Relaxation.........................................The assembler normally performs the following other relaxations. Theycan be disabled by using underscore prefixes (*note Opcode Names:Xtensa Opcodes.), the `--no-transform' command-line option (*noteCommand Line Options: Xtensa Options.), or the `no-transform' directive(*note transform: Transform Directive.).The `MOVI' machine instruction can only materialize values in therange from -2048 to 2047. Values outside this range are bestmaterialized with `L32R' instructions. Thus:movi a0, 100000is assembled into the following machine code:.literal .L1, 100000l32r a0, .L1The `L8UI' machine instruction can only be used with immediateoffsets in the range from 0 to 255. The `L16SI' and `L16UI' machineinstructions can only be used with offsets from 0 to 510. The `L32I'machine instruction can only be used with offsets from 0 to 1020. Aload offset outside these ranges can be materialized with an `L32R'instruction if the destination register of the load is different thanthe source address register. For example:l32i a1, a0, 2040is translated to:.literal .L1, 2040l32r a1, .L1add a1, a0, a1l32i a1, a1, 0If the load destination and source address register are the same, anout-of-range offset causes an error.The Xtensa `ADDI' instruction only allows immediate operands in therange from -128 to 127. There are a number of alternate instructionsequences for the `ADDI' operation. First, if the immediate is 0, the`ADDI' will be turned into a `MOV.N' instruction (or the equivalent`OR' instruction if the code density option is not available). If the`ADDI' immediate is outside of the range -128 to 127, but inside therange -32896 to 32639, an `ADDMI' instruction or `ADDMI'/`ADDI'sequence will be used. Finally, if the immediate is outside of thisrange and a free register is available, an `L32R'/`ADD' sequence willbe used with a literal allocated from the literal pool.For example:addi a5, a6, 0addi a5, a6, 512addi a5, a6, 513addi a5, a6, 50000is assembled into the following:.literal .L1, 50000mov.n a5, a6addmi a5, a6, 0x200addmi a5, a6, 0x200addi a5, a5, 1l32r a5, .L1add a5, a6, a5File: as.info, Node: Xtensa Directives, Prev: Xtensa Relaxation, Up: Xtensa-Dependent9.36.5 Directives-----------------The Xtensa assembler supports a region-based directive syntax:.begin DIRECTIVE [OPTIONS]....end DIRECTIVEAll the Xtensa-specific directives that apply to a region of code usethis syntax.The directive applies to code between the `.begin' and the `.end'.The state of the option after the `.end' reverts to what it was beforethe `.begin'. A nested `.begin'/`.end' region can further change thestate of the directive without having to be aware of its outer state.For example, consider:.begin no-transformL: add a0, a1, a2.begin transformM: add a0, a1, a2.end transformN: add a0, a1, a2.end no-transformThe `ADD' opcodes at `L' and `N' in the outer `no-transform' regionboth result in `ADD' machine instructions, but the assembler selects an`ADD.N' instruction for the `ADD' at `M' in the inner `transform'region.The advantage of this style is that it works well inside macroswhich can preserve the context of their callers.The following directives are available:* Menu:* Schedule Directive:: Enable instruction scheduling.* Longcalls Directive:: Use Indirect Calls for Greater Range.* Transform Directive:: Disable All Assembler Transformations.* Literal Directive:: Intermix Literals with Instructions.* Literal Position Directive:: Specify Inline Literal Pool Locations.* Literal Prefix Directive:: Specify Literal Section Name Prefix.* Absolute Literals Directive:: Control PC-Relative vs. Absolute Literals.File: as.info, Node: Schedule Directive, Next: Longcalls Directive, Up: Xtensa Directives9.36.5.1 schedule.................The `schedule' directive is recognized only for compatibility withTensilica's assembler..begin [no-]schedule.end [no-]scheduleThis directive is ignored and has no effect on `as'.File: as.info, Node: Longcalls Directive, Next: Transform Directive, Prev: Schedule Directive, Up: Xtensa Directives9.36.5.2 longcalls..................The `longcalls' directive enables or disables function call relaxation.*Note Function Call Relaxation: Xtensa Call Relaxation..begin [no-]longcalls.end [no-]longcallsCall relaxation is disabled by default unless the `--longcalls'command-line option is specified. The `longcalls' directive overridesthe default determined by the command-line options.File: as.info, Node: Transform Directive, Next: Literal Directive, Prev: Longcalls Directive, Up: Xtensa Directives9.36.5.3 transform..................This directive enables or disables all assembler transformation,including relaxation (*note Xtensa Relaxation: Xtensa Relaxation.) andoptimization (*note Xtensa Optimizations: Xtensa Optimizations.)..begin [no-]transform.end [no-]transformTransformations are enabled by default unless the `--no-transform'option is used. The `transform' directive overrides the defaultdetermined by the command-line options. An underscore opcode prefix,disabling transformation of that opcode, always takes precedence overboth directives and command-line flags.File: as.info, Node: Literal Directive, Next: Literal Position Directive, Prev: Transform Directive, Up: Xtensa Directives9.36.5.4 literal................The `.literal' directive is used to define literal pool data, i.e.,read-only 32-bit data accessed via `L32R' instructions..literal LABEL, VALUE[, VALUE...]This directive is similar to the standard `.word' directive, exceptthat the actual location of the literal data is determined by theassembler and linker, not by the position of the `.literal' directive.Using this directive gives the assembler freedom to locate the literaldata in the most appropriate place and possibly to combine identicalliterals. For example, the code:entry sp, 40.literal .L1, syml32r a4, .L1can be used to load a pointer to the symbol `sym' into register`a4'. The value of `sym' will not be placed between the `ENTRY' and`L32R' instructions; instead, the assembler puts the data in a literalpool.Literal pools are placed by default in separate literal sections;however, when using the `--text-section-literals' option (*note CommandLine Options: Xtensa Options.), the literal pools for PC-relative mode`L32R' instructions are placed in the current section.(1) These textsection literal pools are created automatically before `ENTRY'instructions and manually after `.literal_position' directives (*noteliteral_position: Literal Position Directive.). If there are nopreceding `ENTRY' instructions, explicit `.literal_position' directivesmust be used to place the text section literal pools; otherwise, `as'will report an error.When literals are placed in separate sections, the literal sectionnames are derived from the names of the sections where the literals aredefined. The base literal section names are `.literal' for PC-relativemode `L32R' instructions and `.lit4' for absolute mode `L32R'instructions (*note absolute-literals: Absolute Literals Directive.).These base names are used for literals defined in the default `.text'section. For literals defined in other sections or within the scope ofa `literal_prefix' directive (*note literal_prefix: Literal PrefixDirective.), the following rules determine the literal section name:1. If the current section is a member of a section group, the literalsection name includes the group name as a suffix to the base`.literal' or `.lit4' name, with a period to separate the basename and group name. The literal section is also made a member ofthe group.2. If the current section name (or `literal_prefix' value) begins with"`.gnu.linkonce.KIND.'", the literal section name is formed byreplacing "`.KIND'" with the base `.literal' or `.lit4' name. Forexample, for literals defined in a section named`.gnu.linkonce.t.func', the literal section will be`.gnu.linkonce.literal.func' or `.gnu.linkonce.lit4.func'.3. If the current section name (or `literal_prefix' value) ends with`.text', the literal section name is formed by replacing thatsuffix with the base `.literal' or `.lit4' name. For example, forliterals defined in a section named `.iram0.text', the literalsection will be `.iram0.literal' or `.iram0.lit4'.4. If none of the preceding conditions apply, the literal sectionname is formed by adding the base `.literal' or `.lit4' name as asuffix to the current section name (or `literal_prefix' value).---------- Footnotes ----------(1) Literals for the `.init' and `.fini' sections are always placedin separate sections, even when `--text-section-literals' is enabled.File: as.info, Node: Literal Position Directive, Next: Literal Prefix Directive, Prev: Literal Directive, Up: Xtensa Directives9.36.5.5 literal_position.........................When using `--text-section-literals' to place literals inline in thesection being assembled, the `.literal_position' directive can be usedto mark a potential location for a literal pool..literal_positionThe `.literal_position' directive is ignored when the`--text-section-literals' option is not used or when `L32R'instructions use the absolute addressing mode.The assembler will automatically place text section literal poolsbefore `ENTRY' instructions, so the `.literal_position' directive isonly needed to specify some other location for a literal pool. You mayneed to add an explicit jump instruction to skip over an inline literalpool.For example, an interrupt vector does not begin with an `ENTRY'instruction so the assembler will be unable to automatically find a goodplace to put a literal pool. Moreover, the code for the interruptvector must be at a specific starting address, so the literal poolcannot come before the start of the code. The literal pool for thevector must be explicitly positioned in the middle of the vector (beforeany uses of the literals, due to the negative offsets used byPC-relative `L32R' instructions). The `.literal_position' directivecan be used to do this. In the following code, the literal for `M'will automatically be aligned correctly and is placed after theunconditional jump..global Mcode_start:j continue.literal_position.align 4continue:movi a4, MFile: as.info, Node: Literal Prefix Directive, Next: Absolute Literals Directive, Prev: Literal Position Directive, Up: Xtensa Directives9.36.5.6 literal_prefix.......................The `literal_prefix' directive allows you to override the defaultliteral section names, which are derived from the names of the sectionswhere the literals are defined..begin literal_prefix [NAME].end literal_prefixFor literals defined within the delimited region, the literal sectionnames are derived from the NAME argument instead of the name of thecurrent section. The rules used to derive the literal section names donot change. *Note literal: Literal Directive. If the NAME argument isomitted, the literal sections revert to the defaults. This directivehas no effect when using the `--text-section-literals' option (*noteCommand Line Options: Xtensa Options.).File: as.info, Node: Absolute Literals Directive, Prev: Literal Prefix Directive, Up: Xtensa Directives9.36.5.7 absolute-literals..........................The `absolute-literals' and `no-absolute-literals' directives controlthe absolute vs. PC-relative mode for `L32R' instructions. These arerelevant only for Xtensa configurations that include the absoluteaddressing option for `L32R' instructions..begin [no-]absolute-literals.end [no-]absolute-literalsThese directives do not change the `L32R' mode--they only cause theassembler to emit the appropriate kind of relocation for `L32R'instructions and to place the literal values in the appropriate section.To change the `L32R' mode, the program must write the `LITBASE' specialregister. It is the programmer's responsibility to keep track of themode and indicate to the assembler which mode is used in each region ofcode.If the Xtensa configuration includes the absolute `L32R' addressingoption, the default is to assume absolute `L32R' addressing unless the`--no-absolute-literals' command-line option is specified. Otherwise,the default is to assume PC-relative `L32R' addressing. The`absolute-literals' directive can then be used to override the defaultdetermined by the command-line options.File: as.info, Node: Reporting Bugs, Next: Acknowledgements, Prev: Machine Dependencies, Up: Top10 Reporting Bugs*****************Your bug reports play an essential role in making `as' reliable.Reporting a bug may help you by bringing a solution to your problem,or it may not. But in any case the principal function of a bug reportis to help the entire community by making the next version of `as' workbetter. Bug reports are your contribution to the maintenance of `as'.In order for a bug report to serve its purpose, you must include theinformation that enables us to fix the bug.* Menu:* Bug Criteria:: Have you found a bug?* Bug Reporting:: How to report bugsFile: as.info, Node: Bug Criteria, Next: Bug Reporting, Up: Reporting Bugs10.1 Have You Found a Bug?==========================If you are not sure whether you have found a bug, here are someguidelines:* If the assembler gets a fatal signal, for any input whatever, thatis a `as' bug. Reliable assemblers never crash.* If `as' produces an error message for valid input, that is a bug.* If `as' does not produce an error message for invalid input, thatis a bug. However, you should note that your idea of "invalidinput" might be our idea of "an extension" or "support fortraditional practice".* If you are an experienced user of assemblers, your suggestions forimprovement of `as' are welcome in any case.File: as.info, Node: Bug Reporting, Prev: Bug Criteria, Up: Reporting Bugs10.2 How to Report Bugs=======================A number of companies and individuals offer support for GNU products.If you obtained `as' from a support organization, we recommend youcontact that organization first.You can find contact information for many support companies andindividuals in the file `etc/SERVICE' in the GNU Emacs distribution.In any event, we also recommend that you send bug reports for `as'to `http://www.sourceware.org/bugzilla/'.The fundamental principle of reporting bugs usefully is this:*report all the facts*. If you are not sure whether to state a fact orleave it out, state it!Often people omit facts because they think they know what causes theproblem and assume that some details do not matter. Thus, you mightassume that the name of a symbol you use in an example does not matter.Well, probably it does not, but one cannot be sure. Perhaps the bugis a stray memory reference which happens to fetch from the locationwhere that name is stored in memory; perhaps, if the name weredifferent, the contents of that location would fool the assembler intodoing the right thing despite the bug. Play it safe and give aspecific, complete example. That is the easiest thing for you to do,and the most helpful.Keep in mind that the purpose of a bug report is to enable us to fixthe bug if it is new to us. Therefore, always write your bug reportson the assumption that the bug has not been reported previously.Sometimes people give a few sketchy facts and ask, "Does this ring abell?" This cannot help us fix a bug, so it is basically useless. Werespond by asking for enough details to enable us to investigate. Youmight as well expedite matters by sending them to begin with.To enable us to fix the bug, you should include all these things:* The version of `as'. `as' announces it if you start it with the`--version' argument.Without this, we will not know whether there is any point inlooking for the bug in the current version of `as'.* Any patches you may have applied to the `as' source.* The type of machine you are using, and the operating system nameand version number.* What compiler (and its version) was used to compile `as'--e.g."`gcc-2.7'".* The command arguments you gave the assembler to assemble yourexample and observe the bug. To guarantee you will not omitsomething important, list them all. A copy of the Makefile (orthe output from make) is sufficient.If we were to try to guess the arguments, we would probably guesswrong and then we might not encounter the bug.* A complete input file that will reproduce the bug. If the bug isobserved when the assembler is invoked via a compiler, send theassembler source, not the high level language source. Mostcompilers will produce the assembler source when run with the `-S'option. If you are using `gcc', use the options `-v--save-temps'; this will save the assembler source in a file withan extension of `.s', and also show you exactly how `as' is beingrun.* A description of what behavior you observe that you believe isincorrect. For example, "It gets a fatal signal."Of course, if the bug is that `as' gets a fatal signal, then wewill certainly notice it. But if the bug is incorrect output, wemight not notice unless it is glaringly wrong. You might as wellnot give us a chance to make a mistake.Even if the problem you experience is a fatal signal, you shouldstill say so explicitly. Suppose something strange is going on,such as, your copy of `as' is out of sync, or you have encountereda bug in the C library on your system. (This has happened!) Yourcopy might crash and ours would not. If you told us to expect acrash, then when ours fails to crash, we would know that the bugwas not happening for us. If you had not told us to expect acrash, then we would not be able to draw any conclusion from ourobservations.* If you wish to suggest changes to the `as' source, send us contextdiffs, as generated by `diff' with the `-u', `-c', or `-p' option.Always send diffs from the old file to the new file. If you evendiscuss something in the `as' source, refer to it by context, notby line number.The line numbers in our development sources will not match thosein your sources. Your line numbers would convey no usefulinformation to us.Here are some things that are not necessary:* A description of the envelope of the bug.Often people who encounter a bug spend a lot of time investigatingwhich changes to the input file will make the bug go away and whichchanges will not affect it.This is often time consuming and not very useful, because the waywe will find the bug is by running a single example under thedebugger with breakpoints, not by pure deduction from a series ofexamples. We recommend that you save your time for something else.Of course, if you can find a simpler example to report _instead_of the original one, that is a convenience for us. Errors in theoutput will be easier to spot, running under the debugger will takeless time, and so on.However, simplification is not vital; if you do not want to dothis, report the bug anyway and send us the entire test case youused.* A patch for the bug.A patch for the bug does help us if it is a good one. But do notomit the necessary information, such as the test case, on theassumption that a patch is all we need. We might see problemswith your patch and decide to fix the problem another way, or wemight not understand it at all.Sometimes with a program as complicated as `as' it is very hard toconstruct an example that will make the program follow a certainpath through the code. If you do not send us the example, we willnot be able to construct one, so we will not be able to verifythat the bug is fixed.And if we cannot understand what bug you are trying to fix, or whyyour patch should be an improvement, we will not install it. Atest case will help us to understand.* A guess about what the bug is or what it depends on.Such guesses are usually wrong. Even we cannot guess right aboutsuch things without first using the debugger to find the facts.File: as.info, Node: Acknowledgements, Next: GNU Free Documentation License, Prev: Reporting Bugs, Up: Top11 Acknowledgements*******************If you have contributed to GAS and your name isn't listed here, it isnot meant as a slight. We just don't know about it. Send mail to themaintainer, and we'll correct the situation. Currently the maintaineris Ken Raeburn (email address `raeburn@cygnus.com').Dean Elsner wrote the original GNU assembler for the VAX.(1)Jay Fenlason maintained GAS for a while, adding support forGDB-specific debug information and the 68k series machines, most of thepreprocessing pass, and extensive changes in `messages.c',`input-file.c', `write.c'.K. Richard Pixley maintained GAS for a while, adding variousenhancements and many bug fixes, including merging support for severalprocessors, breaking GAS up to handle multiple object file format backends (including heavy rewrite, testing, an integration of the coff andb.out back ends), adding configuration including heavy testing andverification of cross assemblers and file splits and renaming,converted GAS to strictly ANSI C including full prototypes, addedsupport for m680[34]0 and cpu32, did considerable work on i960including a COFF port (including considerable amounts of reverseengineering), a SPARC opcode file rewrite, DECstation, rs6000, andhp300hpux host ports, updated "know" assertions and made them work,much other reorganization, cleanup, and lint.Ken Raeburn wrote the high-level BFD interface code to replace mostof the code in format-specific I/O modules.The original VMS support was contributed by David L. Kashtan. EricYoungdale has done much work with it since.The Intel 80386 machine description was written by Eliot Dresselhaus.Minh Tran-Le at IntelliCorp contributed some AIX 386 support.The Motorola 88k machine description was contributed by Devon Bowenof Buffalo University and Torbjorn Granlund of the Swedish Institute ofComputer Science.Keith Knowles at the Open Software Foundation wrote the originalMIPS back end (`tc-mips.c', `tc-mips.h'), and contributed Rose formatsupport (which hasn't been merged in yet). Ralph Campbell worked withthe MIPS code to support a.out format.Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,tc-h8300), and IEEE 695 object file format (obj-ieee), was written bySteve Chamberlain of Cygnus Support. Steve also modified the COFF backend to use BFD for some low-level operations, for use with the H8/300and AMD 29k targets.John Gilmore built the AMD 29000 support, added `.include' support,and simplified the configuration of which versions accept whichdirectives. He updated the 68k machine description so that Motorola'sopcodes always produced fixed-size instructions (e.g., `jsr'), whilesynthetic instructions remained shrinkable (`jbsr'). John fixed manybugs, including true tested cross-compilation support, and one bug inrelaxation that took a week and required the proverbial one-bit fix.Ian Lance Taylor of Cygnus Support merged the Motorola and MITsyntax for the 68k, completed support for some COFF targets (68k, i386SVR3, and SCO Unix), added support for MIPS ECOFF and ELF targets,wrote the initial RS/6000 and PowerPC assembler, and made a few otherminor patches.Steve Chamberlain made GAS able to generate listings.Hewlett-Packard contributed support for the HP9000/300.Jeff Law wrote GAS and BFD support for the native HPPA object format(SOM) along with a fairly extensive HPPA testsuite (for both SOM andELF object formats). This work was supported by both the Center forSoftware Science at the University of Utah and Cygnus Support.Support for ELF format files has been worked on by Mark Eichin ofCygnus Support (original, incomplete implementation for SPARC), PeteHoogenboom and Jeff Law at the University of Utah (HPPA mainly),Michael Meissner of the Open Software Foundation (i386 mainly), and KenRaeburn of Cygnus Support (sparc, and some initial 64-bit support).Linas Vepstas added GAS support for the ESA/390 "IBM 370"architecture.Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wroteGAS and BFD support for openVMS/Alpha.Timothy Wall, Michael Hayes, and Greg Smart contributed to thevarious tic* flavors.David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg fromTensilica, Inc. added support for Xtensa processors.Several engineers at Cygnus Support have also provided many smallbug fixes and configuration enhancements.Many others have contributed large or small bugfixes andenhancements. If you have contributed significant work and are notmentioned on this list, and want to be, let us know. Some of thehistory has been lost; we are not intentionally leaving anyone out.---------- Footnotes ----------(1) Any more details?File: as.info, Node: GNU Free Documentation License, Next: AS Index, Prev: Acknowledgements, Up: TopAppendix A GNU Free Documentation License*****************************************Version 1.1, March 2000Copyright (C) 2000, 2003 Free Software Foundation, Inc.51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USAEveryone is permitted to copy and distribute verbatim copiesof this license document, but changing it is not allowed.0. PREAMBLEThe purpose of this License is to make a manual, textbook, or otherwritten document "free" in the sense of freedom: to assure everyonethe effective freedom to copy and redistribute it, with or withoutmodifying it, either commercially or noncommercially. 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