bignum-copy.c   [plain text]

/* bignum_copy.c - copy a bignum
   Copyright 1987, 1990, 1991, 1992, 1993, 2000
   Free Software Foundation, Inc.

   This file is part of GAS, the GNU Assembler.

   GAS is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   GAS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GAS; see the file COPYING.  If not, write to
   the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#include "as.h"

/*
 *			bignum_copy ()
 *
 * Copy a bignum from in to out.
 * If the output is shorter than the input, copy lower-order littlenums.
 * Return 0 or the number of significant littlenums dropped.
 * Assumes littlenum arrays are densely packed: no unused chars between
 * the littlenums. Uses memcpy() to move littlenums, and wants to
 * know length (in chars) of the input bignum.
 */

/* void */
int
bignum_copy (register LITTLENUM_TYPE *in,
	     register int in_length,	/* in sizeof(littlenum)s */
	     register LITTLENUM_TYPE *out,
	     register int out_length	/* in sizeof(littlenum)s */)
{
  int significant_littlenums_dropped;

  if (out_length < in_length)
    {
      LITTLENUM_TYPE *p;	/* -> most significant (non-zero) input
				      littlenum.  */

      memcpy ((void *) out, (void *) in,
	      (unsigned int) out_length << LITTLENUM_SHIFT);
      for (p = in + in_length - 1; p >= in; --p)
	{
	  if (*p)
	    break;
	}
      significant_littlenums_dropped = p - in - in_length + 1;

      if (significant_littlenums_dropped < 0)
	{
	  significant_littlenums_dropped = 0;
	}
    }
  else
    {
      memcpy ((char *) out, (char *) in,
	      (unsigned int) in_length << LITTLENUM_SHIFT);

      if (out_length > in_length)
	{
	  memset ((char *) (out + in_length),
		  '\0',
		  (unsigned int) (out_length - in_length) << LITTLENUM_SHIFT);
	}

      significant_littlenums_dropped = 0;
    }

  return (significant_littlenums_dropped);
}				/* bignum_copy() */

/* end of bignum-copy.c */