gnu/usr.bin/as/bignum-copy.c

/* bignum_copy.c - copy a bignum
   Copyright (C) 1987, 1990, 1991, 1992 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, 675 Mass Ave, Cambridge, MA 02139, USA. */

#ifndef lint
static char rcsid[] = "$Id: bignum-copy.c,v 1.3 1993/10/02 20:57:18 pk Exp $";
#endif

#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(in, in_length, out, out_length)
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,
                      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,
                      in_length << LITTLENUM_SHIFT);

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

                significant_littlenums_dropped = 0;
        }

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

/* end of bignum-copy.c */