* M_APM - mapmpwr2.c
*
* Copyright (C) 2002 - 2007 Michael C. Ring
*
* Permission to use, copy, and distribute this software and its
* documentation for any purpose with or without fee is hereby granted,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation.
*
* Permission to modify the software is granted. Permission to distribute
* the modified code is granted. Modifications are to be distributed by
* using the file 'license.txt' as a template to modify the file header.
* 'license.txt' is available in the official MAPM distribution.
*
* This software is provided "as is" without express or implied warranty.
*/
* $Id: mapmpwr2.c,v 1.4 2007/12/03 01:56:21 mike Exp $
*
* This file contains the Integer Power function and the result
* is NOT ROUNDED. The exponent must be an integer >= zero.
*
* This will typically be used in an application where full integer
* precision is required to be maintained.
*
* $Log: mapmpwr2.c,v $
* Revision 1.4 2007/12/03 01:56:21 mike
* Update license
*
* Revision 1.3 2003/07/21 20:38:06 mike
* Modify error messages to be in a consistent format.
*
* Revision 1.2 2003/03/31 21:51:23 mike
* call generic error handling function
*
* Revision 1.1 2002/11/03 21:02:04 mike
* Initial revision
*/
#include "m_apm_lc.h"
void m_apm_integer_pow_nr(M_APM rr, M_APM aa, int mexp)
{
M_APM tmp0, tmpy, tmpz;
int nexp, ii;
if (mexp == 0)
{
m_apm_copy(rr, MM_One);
return;
}
else
{
if (mexp < 0)
{
M_apm_log_error_msg(M_APM_RETURN,
"\'m_apm_integer_pow_nr\', Negative exponent");
M_set_to_zero(rr);
return;
}
}
if (mexp == 1)
{
m_apm_copy(rr, aa);
return;
}
if (mexp == 2)
{
m_apm_multiply(rr, aa, aa);
return;
}
nexp = mexp;
if (aa->m_apm_sign == 0)
{
M_set_to_zero(rr);
return;
}
tmp0 = M_get_stack_var();
tmpy = M_get_stack_var();
tmpz = M_get_stack_var();
m_apm_copy(tmpy, MM_One);
m_apm_copy(tmpz, aa);
while (TRUE)
{
ii = nexp & 1;
nexp = nexp >> 1;
if (ii != 0)
{
m_apm_multiply(tmp0, tmpy, tmpz);
if (nexp == 0)
break;
m_apm_copy(tmpy, tmp0);
}
m_apm_multiply(tmp0, tmpz, tmpz);
m_apm_copy(tmpz, tmp0);
}
m_apm_copy(rr, tmp0);
M_restore_stack(3);
}
