1  /* mpn_redc_1.  Set rp[] <- up[]/R^n mod mp[].  Clobber up[].
       2     mp[] is n limbs; up[] is 2n limbs.
       3  
       4     THIS IS AN INTERNAL FUNCTION WITH A MUTABLE INTERFACE.  IT IS ONLY
       5     SAFE TO REACH THIS FUNCTION THROUGH DOCUMENTED INTERFACES.
       6  
       7  Copyright (C) 2000-2002, 2004, 2008, 2009, 2012 Free Software Foundation, Inc.
       8  
       9  This file is part of the GNU MP Library.
      10  
      11  The GNU MP Library is free software; you can redistribute it and/or modify
      12  it under the terms of either:
      13  
      14    * the GNU Lesser General Public License as published by the Free
      15      Software Foundation; either version 3 of the License, or (at your
      16      option) any later version.
      17  
      18  or
      19  
      20    * the GNU General Public License as published by the Free Software
      21      Foundation; either version 2 of the License, or (at your option) any
      22      later version.
      23  
      24  or both in parallel, as here.
      25  
      26  The GNU MP Library is distributed in the hope that it will be useful, but
      27  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      28  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      29  for more details.
      30  
      31  You should have received copies of the GNU General Public License and the
      32  GNU Lesser General Public License along with the GNU MP Library.  If not,
      33  see https://www.gnu.org/licenses/.  */
      34  
      35  #include "gmp-impl.h"
      36  
      37  mp_limb_t
      38  mpn_redc_1 (mp_ptr rp, mp_ptr up, mp_srcptr mp, mp_size_t n, mp_limb_t invm)
      39  {
      40    mp_size_t j;
      41    mp_limb_t cy;
      42  
      43    ASSERT (n > 0);
      44    ASSERT_MPN (up, 2*n);
      45  
      46    for (j = n - 1; j >= 0; j--)
      47      {
      48        cy = mpn_addmul_1 (up, mp, n, (up[0] * invm) & GMP_NUMB_MASK);
      49        ASSERT (up[0] == 0);
      50        up[0] = cy;
      51        up++;
      52      }
      53  
      54    cy = mpn_add_n (rp, up, up - n, n);
      55    return cy;
      56  }