gas/bignum-copy.c

   1 /* bignum_copy.c - copy a bignum
   2    Copyright (C) 1987, 1990, 1991, 1992 Free Software Foundation, Inc.
   3
   4    This file is part of GAS, the GNU Assembler.
   5
   6    GAS is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    GAS is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GAS; see the file COPYING.  If not, write to
  18    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
  19
  20 #include "as.h"
  21
  22 #ifdef USG
  23 #define bzero(s,n) memset(s,0,n)
  24 #define bcopy(from,to,n) memcpy(to,from,n)
  25 #endif
  26
  27 /*
  28  *                      bignum_copy ()
  29  *
  30  * Copy a bignum from in to out.
  31  * If the output is shorter than the input, copy lower-order littlenums.
  32  * Return 0 or the number of significant littlenums dropped.
  33  * Assumes littlenum arrays are densely packed: no unused chars between
  34  * the littlenums. Uses bcopy() to move littlenums, and wants to
  35  * know length (in chars) of the input bignum.
  36  */
  37
  38 /* void */
  39 int
  40     bignum_copy(in, in_length, out, out_length)
  41 register LITTLENUM_TYPE *in;
  42 register int in_length; /* in sizeof(littlenum)s */
  43 register LITTLENUM_TYPE *out;
  44 register int out_length; /* in sizeof(littlenum)s */
  45 {
  46         int significant_littlenums_dropped;
  47
  48         if (out_length < in_length) {
  49                 LITTLENUM_TYPE *p; /* -> most significant (non-zero) input
  50                                       littlenum. */
  51
  52                 bcopy((char *) in, (char *) out,
  53                       out_length << LITTLENUM_SHIFT);
  54                 for (p = in + in_length - 1; p >= in; --p) {
  55                         if (* p) break;
  56                 }
  57                 significant_littlenums_dropped = p - in - in_length + 1;
  58
  59                 if (significant_littlenums_dropped < 0) {
  60                         significant_littlenums_dropped = 0;
  61                 }
  62         } else {
  63                 bcopy((char *) in, (char *) out,
  64                       in_length << LITTLENUM_SHIFT);
  65
  66                 if (out_length > in_length) {
  67                         bzero((char *) (out + out_length),
  68                               (out_length - in_length) << LITTLENUM_SHIFT);
  69                 }
  70
  71                 significant_littlenums_dropped = 0;
  72         }
  73
  74         return(significant_littlenums_dropped);
  75 } /* bignum_copy() */
  76
  77 /* end of bignum-copy.c */