xref: /dflybsd-src/contrib/gmp/mpn/generic/redc_1_sec.c (revision 86d7f5d305c6adaa56ff4582ece9859d73106103)

/* mpn_redc_1_sec.  Set cp[] <- up[]/R^n mod mp[].  Clobber up[].
   mp[] is n limbs; up[] is 2n limbs.

   THIS IS AN INTERNAL FUNCTION WITH A MUTABLE INTERFACE.  IT IS ONLY
   SAFE TO REACH THIS FUNCTION THROUGH DOCUMENTED INTERFACES.

Copyright (C) 2000, 2001, 2002, 2004, 2008, 2009 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 3 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.  If not, see http://www.gnu.org/licenses/.  */

#include "gmp.h"
#include "gmp-impl.h"

void
mpn_redc_1_sec (mp_ptr rp, mp_ptr up, mp_srcptr mp, mp_size_t n, mp_limb_t invm)
{
  mp_size_t j;
  mp_limb_t cy;

  ASSERT (n > 0);
  ASSERT_MPN (up, 2*n);

  for (j = n - 1; j >= 0; j--)
    {
      cy = mpn_addmul_1 (up, mp, n, (up[0] * invm) & GMP_NUMB_MASK);
      ASSERT (up[0] == 0);
      up[0] = cy;
      up++;
    }
  cy = mpn_add_n (rp, up, up - n, n);
  mpn_subcnd_n (rp, rp, mp, n, cy);
}