6ec01646dc
BMakefiles and other bits will follow. Requested by: Andrey Chernov Made world by: Chuck Robey
121 lines
3.0 KiB
C
121 lines
3.0 KiB
C
/* mpz_sub -- Subtract two integers.
|
|
|
|
Copyright (C) 1991, 1993, 1994, 1996 Free Software Foundation, Inc.
|
|
|
|
This file is part of the GNU MP Library.
|
|
|
|
The GNU MP Library is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU Library General Public License as published by
|
|
the Free Software Foundation; either version 2 of the License, or (at your
|
|
option) any later version.
|
|
|
|
The GNU MP Library 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 Library General Public
|
|
License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public License
|
|
along with the GNU MP Library; see the file COPYING.LIB. If not, write to
|
|
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
|
|
MA 02111-1307, USA. */
|
|
|
|
#include "gmp.h"
|
|
#include "gmp-impl.h"
|
|
|
|
#ifndef BERKELEY_MP
|
|
void
|
|
#if __STDC__
|
|
mpz_sub (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
|
|
#else
|
|
mpz_sub (w, u, v)
|
|
mpz_ptr w;
|
|
mpz_srcptr u;
|
|
mpz_srcptr v;
|
|
#endif
|
|
#else /* BERKELEY_MP */
|
|
void
|
|
#if __STDC__
|
|
msub (mpz_srcptr u, mpz_srcptr v, mpz_ptr w)
|
|
#else
|
|
msub (u, v, w)
|
|
mpz_srcptr u;
|
|
mpz_srcptr v;
|
|
mpz_ptr w;
|
|
#endif
|
|
#endif /* BERKELEY_MP */
|
|
{
|
|
mp_srcptr up, vp;
|
|
mp_ptr wp;
|
|
mp_size_t usize, vsize, wsize;
|
|
mp_size_t abs_usize;
|
|
mp_size_t abs_vsize;
|
|
|
|
usize = u->_mp_size;
|
|
vsize = -v->_mp_size; /* The "-" makes the difference from mpz_add */
|
|
abs_usize = ABS (usize);
|
|
abs_vsize = ABS (vsize);
|
|
|
|
if (abs_usize < abs_vsize)
|
|
{
|
|
/* Swap U and V. */
|
|
{const __mpz_struct *t = u; u = v; v = t;}
|
|
{mp_size_t t = usize; usize = vsize; vsize = t;}
|
|
{mp_size_t t = abs_usize; abs_usize = abs_vsize; abs_vsize = t;}
|
|
}
|
|
|
|
/* True: ABS_USIZE >= ABS_VSIZE. */
|
|
|
|
/* If not space for w (and possible carry), increase space. */
|
|
wsize = abs_usize + 1;
|
|
if (w->_mp_alloc < wsize)
|
|
_mpz_realloc (w, wsize);
|
|
|
|
/* These must be after realloc (u or v may be the same as w). */
|
|
up = u->_mp_d;
|
|
vp = v->_mp_d;
|
|
wp = w->_mp_d;
|
|
|
|
if ((usize ^ vsize) < 0)
|
|
{
|
|
/* U and V have different sign. Need to compare them to determine
|
|
which operand to subtract from which. */
|
|
|
|
/* This test is right since ABS_USIZE >= ABS_VSIZE. */
|
|
if (abs_usize != abs_vsize)
|
|
{
|
|
mpn_sub (wp, up, abs_usize, vp, abs_vsize);
|
|
wsize = abs_usize;
|
|
MPN_NORMALIZE (wp, wsize);
|
|
if (usize < 0)
|
|
wsize = -wsize;
|
|
}
|
|
else if (mpn_cmp (up, vp, abs_usize) < 0)
|
|
{
|
|
mpn_sub_n (wp, vp, up, abs_usize);
|
|
wsize = abs_usize;
|
|
MPN_NORMALIZE (wp, wsize);
|
|
if (usize >= 0)
|
|
wsize = -wsize;
|
|
}
|
|
else
|
|
{
|
|
mpn_sub_n (wp, up, vp, abs_usize);
|
|
wsize = abs_usize;
|
|
MPN_NORMALIZE (wp, wsize);
|
|
if (usize < 0)
|
|
wsize = -wsize;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* U and V have same sign. Add them. */
|
|
mp_limb_t cy_limb = mpn_add (wp, up, abs_usize, vp, abs_vsize);
|
|
wp[abs_usize] = cy_limb;
|
|
wsize = abs_usize + cy_limb;
|
|
if (usize < 0)
|
|
wsize = -wsize;
|
|
}
|
|
|
|
w->_mp_size = wsize;
|
|
}
|