submul_1.c

最优秀的大数计算源码,适合各种大数的计算,底层对各种机器进行汇编优化,速度最快

/* mpn_submul_1 for Cray PVP.

Copyright 1996, 2000, 2001 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 Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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 Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser 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"

mp_limb_t
mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t limb)
{
  mp_limb_t p0[n], p1[n], tp[n];
  mp_limb_t cy_limb;

  GMPN_MULWW (p1, p0, up, &n, &limb);
  cy_limb = mpn_sub_n (tp, rp, p0, n);
  rp[0] = tp[0];
  if (n != 1)
    cy_limb += mpn_sub_n (rp + 1, tp + 1, p1, n - 1);
  cy_limb += p1[n - 1];

  return cy_limb;
}