github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/generic/pre_mod_1.c (about)

     1  /* mpn_preinv_mod_1 (up, un, d, dinv) -- Divide (UP,,UN) by the normalized D.
     2     DINV should be 2^(2*GMP_LIMB_BITS) / D - 2^GMP_LIMB_BITS.
     3     Return the single-limb remainder.
     4  
     5  Copyright 1991, 1993, 1994, 2000-2002, 2004, 2005 Free Software Foundation,
     6  Inc.
     7  
     8  This file is part of the GNU MP Library.
     9  
    10  The GNU MP Library is free software; you can redistribute it and/or modify
    11  it under the terms of either:
    12  
    13    * the GNU Lesser General Public License as published by the Free
    14      Software Foundation; either version 3 of the License, or (at your
    15      option) any later version.
    16  
    17  or
    18  
    19    * the GNU General Public License as published by the Free Software
    20      Foundation; either version 2 of the License, or (at your option) any
    21      later version.
    22  
    23  or both in parallel, as here.
    24  
    25  The GNU MP Library is distributed in the hope that it will be useful, but
    26  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    27  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    28  for more details.
    29  
    30  You should have received copies of the GNU General Public License and the
    31  GNU Lesser General Public License along with the GNU MP Library.  If not,
    32  see https://www.gnu.org/licenses/.  */
    33  
    34  #include "gmp.h"
    35  #include "gmp-impl.h"
    36  #include "longlong.h"
    37  
    38  
    39  /* This function used to be documented, but is now considered obsolete.  It
    40     continues to exist for binary compatibility, even when not required
    41     internally.  */
    42  
    43  mp_limb_t
    44  mpn_preinv_mod_1 (mp_srcptr up, mp_size_t un, mp_limb_t d, mp_limb_t dinv)
    45  {
    46    mp_size_t i;
    47    mp_limb_t n0, r;
    48  
    49    ASSERT (un >= 1);
    50    ASSERT (d & GMP_LIMB_HIGHBIT);
    51  
    52    r = up[un - 1];
    53    if (r >= d)
    54      r -= d;
    55  
    56    for (i = un - 2; i >= 0; i--)
    57      {
    58        n0 = up[i];
    59        udiv_rnnd_preinv (r, r, n0, d, dinv);
    60      }
    61    return r;
    62  }