submul_1.c revision 1.1.1.1 
1/* mpn_submul_1 for Cray PVP.
2
3Copyright 1996, 2000, 2001 Free Software Foundation, Inc.
4
5This file is part of the GNU MP Library.
6
7The GNU MP Library is free software; you can redistribute it and/or modify
8it under the terms of the GNU Lesser General Public License as published by
9the Free Software Foundation; either version 3 of the License, or (at your
10option) any later version.
11
12The GNU MP Library is distributed in the hope that it will be useful, but
13WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
15License for more details.
16
17You should have received a copy of the GNU Lesser General Public License
18along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
19
20
21#include "gmp.h"
22#include "gmp-impl.h"
23
24mp_limb_t
25mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t limb)
26{
27  mp_limb_t p0[n], p1[n], tp[n];
28  mp_limb_t cy_limb;
29
30  GMPN_MULWW (p1, p0, up, &n, &limb);
31  cy_limb = mpn_sub_n (tp, rp, p0, n);
32  rp[0] = tp[0];
33  if (n != 1)
34    cy_limb += mpn_sub_n (rp + 1, tp + 1, p1, n - 1);
35  cy_limb += p1[n - 1];
36
37  return cy_limb;
38}
39