source/libs/gmp/gmp-src/mpn/generic/sub_n.c

   1 /* mpn_sub_n -- Subtract equal length limb vectors.
   2
   3 Copyright 1992-1994, 1996, 2000, 2002, 2009 Free Software Foundation, Inc.
   4
   5 This file is part of the GNU MP Library.
   6
   7 The GNU MP Library is free software; you can redistribute it and/or modify
   8 it under the terms of either:
   9
  10   * the GNU Lesser General Public License as published by the Free
  11     Software Foundation; either version 3 of the License, or (at your
  12     option) any later version.
  13
  14 or
  15
  16   * the GNU General Public License as published by the Free Software
  17     Foundation; either version 2 of the License, or (at your option) any
  18     later version.
  19
  20 or both in parallel, as here.
  21
  22 The GNU MP Library is distributed in the hope that it will be useful, but
  23 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  24 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  25 for more details.
  26
  27 You should have received copies of the GNU General Public License and the
  28 GNU Lesser General Public License along with the GNU MP Library.  If not,
  29 see https://www.gnu.org/licenses/.  */
  30
  31 #include "gmp.h"
  32 #include "gmp-impl.h"
  33
  34
  35 #if GMP_NAIL_BITS == 0
  36
  37 mp_limb_t
  38 mpn_sub_n (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
  39 {
  40   mp_limb_t ul, vl, sl, rl, cy, cy1, cy2;
  41
  42   ASSERT (n >= 1);
  43   ASSERT (MPN_SAME_OR_INCR_P (rp, up, n));
  44   ASSERT (MPN_SAME_OR_INCR_P (rp, vp, n));
  45
  46   cy = 0;
  47   do
  48     {
  49       ul = *up++;
  50       vl = *vp++;
  51       sl = ul - vl;
  52       cy1 = sl > ul;
  53       rl = sl - cy;
  54       cy2 = rl > sl;
  55       cy = cy1 | cy2;
  56       *rp++ = rl;
  57     }
  58   while (--n != 0);
  59
  60   return cy;
  61 }
  62
  63 #endif
  64
  65 #if GMP_NAIL_BITS >= 1
  66
  67 mp_limb_t
  68 mpn_sub_n (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
  69 {
  70   mp_limb_t ul, vl, rl, cy;
  71
  72   ASSERT (n >= 1);
  73   ASSERT (MPN_SAME_OR_INCR_P (rp, up, n));
  74   ASSERT (MPN_SAME_OR_INCR_P (rp, vp, n));
  75
  76   cy = 0;
  77   do
  78     {
  79       ul = *up++;
  80       vl = *vp++;
  81       rl = ul - vl - cy;
  82       cy = rl >> (GMP_LIMB_BITS - 1);
  83       *rp++ = rl & GMP_NUMB_MASK;
  84     }
  85   while (--n != 0);
  86
  87   return cy;
  88 }
  89
  90 #endif