* PackBits.cpp
* Copyright 1999-2000 Y.Takagi. All Rights Reserved.
*/
#ifdef DBG_CON_STREAM
#include <fstream>
#endif
#include <stdio.h>
#include <string.h>
#include "PackBits.h"
using namespace std;
#define MAXINBYTES 127
#define CONTROL1(i) -i
#define CONTROL2(i) i
enum STATUS {
INITIAL,
UNDECIDED,
UNMATCHED,
MATCHED
};
#define WRITE_TO_RUN_BUF(byte) \
{ \
if (write) \
*runbuf ++ = byte; \
else \
runbuf ++; \
}
#define WRITE_CONTROL(byte) \
{ \
if (write) \
*control = byte; \
}
template <bool write>
class PackBits {
public:
static int Run(unsigned char* destination, const unsigned char* source, int n)
{
int i;
unsigned char* control;
unsigned char* runbuf;
unsigned char thisbyte;
unsigned char runbyte;
STATUS status;
i = 0;
status = INITIAL;
control = runbuf = destination;
runbyte = *source++;
while (--n) {
thisbyte = *source++;
switch (status) {
case INITIAL:
control = runbuf++;
WRITE_TO_RUN_BUF(runbyte);
if (thisbyte == runbyte) {
status = UNDECIDED;
} else {
runbyte = thisbyte;
status = UNMATCHED;
}
i = 1;
break;
case UNDECIDED:
if (i == MAXINBYTES) {
WRITE_CONTROL(CONTROL2(i));
WRITE_TO_RUN_BUF(runbyte);
runbyte = thisbyte;
status = INITIAL;
} else if (thisbyte == runbyte) {
if (i > 1) {
WRITE_CONTROL(CONTROL2(i - 2));
control = runbuf - 1;
}
i = 2;
status = MATCHED;
} else {
WRITE_TO_RUN_BUF(runbyte);
runbyte = thisbyte;
status = UNMATCHED;
i++;
}
break;
case UNMATCHED:
if (i == MAXINBYTES) {
WRITE_CONTROL(CONTROL2(i));
status = INITIAL;
} else {
if (thisbyte == runbyte) {
status = UNDECIDED;
}
i++;
}
WRITE_TO_RUN_BUF(runbyte);
runbyte = thisbyte;
break;
case MATCHED:
if ((thisbyte != runbyte) || (i == MAXINBYTES)) {
runbuf = control;
WRITE_TO_RUN_BUF(CONTROL1(i));
WRITE_TO_RUN_BUF(runbyte);
runbyte = thisbyte;
status = INITIAL;
} else {
i++;
}
break;
}
}
switch (status) {
case INITIAL:
WRITE_TO_RUN_BUF(CONTROL2(1));
break;
case UNDECIDED:
case UNMATCHED:
WRITE_CONTROL(CONTROL2(i));
break;
case MATCHED:
runbuf = control;
WRITE_TO_RUN_BUF(CONTROL1(i));
break;
}
WRITE_TO_RUN_BUF(runbyte);
return runbuf - destination;
}
};
int pack_bits_size(const unsigned char* source, int size)
{
PackBits<false> compressedSizeCalculator;
return compressedSizeCalculator.Run(NULL, source, size);
}
int pack_bits(unsigned char* destination, const unsigned char* source, int size)
{
PackBits<true> compressor;
return compressor.Run(destination, source, size);
}
#ifdef DBG_CON_STREAM
int main(int argc, char **argv)
{
if (argc < 2) {
return -1;
}
FILE *input = fopen(*++argv, "rb");
if (input == NULL) {
return -1;
}
FILE *output = fopen("rle.out", "wb");
if (output == NULL) {
fclose(input);
return -1;
}
fseek(input, 0, SEEK_END);
long size = ftell(input);
fseek(input, 0, SEEK_SET);
unsigned char* source = new unsigned char[size];
fread(source, size, 1, input);
long outSize = pack_bits_size(source, size);
printf("input size: %d\noutput size: %d\n", (int)size, (int)outSize);
unsigned char* destination = new unsigned char[outSize];
int cnt = pack_bits(destination, source, size);
fwrite(destination, cnt, 1, output);
fclose(input);
fclose(output);
delete [] source;
delete [] destination;
}
#endif
