gas/bignum-copy.c

   1 /* bignum_copy.c - copy a bignum
   2    Copyright (C) 1987, 1990, 1991 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 1, 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 /* static const char rcsid[] = "$Id$"; */
  21
  22 #include "as.h"
  23
  24 #ifdef USG
  25 #define bzero(s,n) memset(s,0,n)
  26 #define bcopy(from,to,n) memcpy(to,from,n)
  27 #endif
  28
  29 /*
  30  *                      bignum_copy ()
  31  *
  32  * Copy a bignum from in to out.
  33  * If the output is shorter than the input, copy lower-order littlenums.
  34  * Return 0 or the number of significant littlenums dropped.
  35  * Assumes littlenum arrays are densely packed: no unused chars between
  36  * the littlenums. Uses bcopy() to move littlenums, and wants to
  37  * know length (in chars) of the input bignum.
  38  */
  39
  40 /* void */
  41 int
  42 bignum_copy (in, in_length, out, out_length)
  43      register LITTLENUM_TYPE *  in;
  44      register int               in_length; /* in sizeof(littlenum)s */
  45      register LITTLENUM_TYPE *  out;
  46      register int               out_length; /* in sizeof(littlenum)s */
  47 {
  48   register int  significant_littlenums_dropped;
  49
  50   if (out_length < in_length)
  51     {
  52       register LITTLENUM_TYPE * p; /* -> most significant (non-zero) input littlenum. */
  53
  54       bcopy ((char *)in, (char *)out, out_length << LITTLENUM_SHIFT);
  55       for (p = in + in_length - 1;   p >= in;   -- p)
  56         {
  57           if (* p) break;
  58         }
  59       significant_littlenums_dropped = p - in - in_length + 1;
  60       if (significant_littlenums_dropped < 0)
  61         {
  62           significant_littlenums_dropped = 0;
  63         }
  64     }
  65   else
  66     {
  67       bcopy ((char *)in, (char *)out, in_length << LITTLENUM_SHIFT);
  68       if (out_length > in_length)
  69         {
  70           bzero ((char *)(out + out_length), (out_length - in_length) << LITTLENUM_SHIFT);
  71         }
  72       significant_littlenums_dropped = 0;
  73     }
  74   return (significant_littlenums_dropped);
  75 }
  76
  77 /* end: bignum_copy.c */