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Member "mapm_4.9.5a/mapmpwr2.c" (21 Feb 2010, 2696 Bytes) of package /linux/misc/old/mapm-4.9.5a.tar.gz:

    1 
    2 /* 
    3  *  M_APM  -  mapmpwr2.c
    4  *
    5  *  Copyright (C) 2002 - 2007   Michael C. Ring
    6  *
    7  *  Permission to use, copy, and distribute this software and its
    8  *  documentation for any purpose with or without fee is hereby granted,
    9  *  provided that the above copyright notice appear in all copies and
   10  *  that both that copyright notice and this permission notice appear
   11  *  in supporting documentation.
   12  *
   13  *  Permission to modify the software is granted. Permission to distribute
   14  *  the modified code is granted. Modifications are to be distributed by
   15  *  using the file 'license.txt' as a template to modify the file header.
   16  *  'license.txt' is available in the official MAPM distribution.
   17  *
   18  *  This software is provided "as is" without express or implied warranty.
   19  */
   20 
   21 /*
   22  *      $Id: mapmpwr2.c,v 1.4 2007/12/03 01:56:21 mike Exp $
   23  *
   24  *      This file contains the Integer Power function and the result 
   25  *  is NOT ROUNDED. The exponent must be an integer >= zero.
   26  *
   27  *      This will typically be used in an application where full integer
   28  *  precision is required to be maintained.
   29  *
   30  *      $Log: mapmpwr2.c,v $
   31  *      Revision 1.4  2007/12/03 01:56:21  mike
   32  *      Update license
   33  *
   34  *      Revision 1.3  2003/07/21 20:38:06  mike
   35  *      Modify error messages to be in a consistent format.
   36  *
   37  *      Revision 1.2  2003/03/31 21:51:23  mike
   38  *      call generic error handling function
   39  *
   40  *      Revision 1.1  2002/11/03 21:02:04  mike
   41  *      Initial revision
   42  */
   43 
   44 #include "m_apm_lc.h"
   45 
   46 /****************************************************************************/
   47 void    m_apm_integer_pow_nr(M_APM rr, M_APM aa, int mexp)
   48 {
   49 M_APM   tmp0, tmpy, tmpz;
   50 int nexp, ii;
   51 
   52 if (mexp == 0)
   53   {
   54    m_apm_copy(rr, MM_One);
   55    return;
   56   }
   57 else
   58   {
   59    if (mexp < 0)
   60      {
   61       M_apm_log_error_msg(M_APM_RETURN,
   62             "\'m_apm_integer_pow_nr\', Negative exponent");
   63 
   64       M_set_to_zero(rr);
   65       return;
   66      }
   67   }
   68 
   69 if (mexp == 1)
   70   {
   71    m_apm_copy(rr, aa);
   72    return;
   73   }
   74 
   75 if (mexp == 2)
   76   {
   77    m_apm_multiply(rr, aa, aa);
   78    return;
   79   }
   80 
   81 nexp = mexp;
   82 
   83 if (aa->m_apm_sign == 0)
   84   {
   85    M_set_to_zero(rr);
   86    return;
   87   }
   88 
   89 tmp0 = M_get_stack_var();
   90 tmpy = M_get_stack_var();
   91 tmpz = M_get_stack_var();
   92 
   93 m_apm_copy(tmpy, MM_One);
   94 m_apm_copy(tmpz, aa);
   95 
   96 while (TRUE)
   97   {
   98    ii   = nexp & 1;
   99    nexp = nexp >> 1;
  100 
  101    if (ii != 0)                       /* exponent -was- odd */
  102      {
  103       m_apm_multiply(tmp0, tmpy, tmpz);
  104 
  105       if (nexp == 0)
  106         break;
  107 
  108       m_apm_copy(tmpy, tmp0);
  109      }
  110 
  111    m_apm_multiply(tmp0, tmpz, tmpz);
  112    m_apm_copy(tmpz, tmp0);
  113   }
  114 
  115 m_apm_copy(rr, tmp0);
  116 
  117 M_restore_stack(3);
  118 }
  119 /****************************************************************************/
  120