github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/generic/submul_1.c (about)

     1  /* mpn_submul_1 -- multiply the N long limb vector pointed to by UP by VL,
     2     subtract the N least significant limbs of the product from the limb
     3     vector pointed to by RP.  Return the most significant limb of the
     4     product, adjusted for carry-out from the subtraction.
     5  
     6  Copyright 1992-1994, 1996, 2000, 2002, 2004 Free Software Foundation, 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  #if GMP_NAIL_BITS == 0
    40  
    41  mp_limb_t
    42  mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl)
    43  {
    44    mp_limb_t ul, cl, hpl, lpl, rl;
    45  
    46    ASSERT (n >= 1);
    47    ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n));
    48  
    49    cl = 0;
    50    do
    51      {
    52        ul = *up++;
    53        umul_ppmm (hpl, lpl, ul, vl);
    54  
    55        lpl += cl;
    56        cl = (lpl < cl) + hpl;
    57  
    58        rl = *rp;
    59        lpl = rl - lpl;
    60        cl += lpl > rl;
    61        *rp++ = lpl;
    62      }
    63    while (--n != 0);
    64  
    65    return cl;
    66  }
    67  
    68  #endif
    69  
    70  #if GMP_NAIL_BITS == 1
    71  
    72  mp_limb_t
    73  mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl)
    74  {
    75    mp_limb_t shifted_vl, ul, rl, lpl, hpl, prev_hpl, cl, xl, c1, c2, c3;
    76  
    77    ASSERT (n >= 1);
    78    ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n));
    79    ASSERT_MPN (rp, n);
    80    ASSERT_MPN (up, n);
    81    ASSERT_LIMB (vl);
    82  
    83    shifted_vl = vl << GMP_NAIL_BITS;
    84    cl = 0;
    85    prev_hpl = 0;
    86    do
    87      {
    88        ul = *up++;
    89        rl = *rp;
    90        umul_ppmm (hpl, lpl, ul, shifted_vl);
    91        lpl >>= GMP_NAIL_BITS;
    92        SUBC_LIMB (c1, xl, rl, prev_hpl);
    93        SUBC_LIMB (c2, xl, xl, lpl);
    94        SUBC_LIMB (c3, xl, xl, cl);
    95        cl = c1 + c2 + c3;
    96        *rp++ = xl;
    97        prev_hpl = hpl;
    98      }
    99    while (--n != 0);
   100  
   101    return prev_hpl + cl;
   102  }
   103  
   104  #endif
   105  
   106  #if GMP_NAIL_BITS >= 2
   107  
   108  mp_limb_t
   109  mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl)
   110  {
   111    mp_limb_t shifted_vl, ul, rl, lpl, hpl, prev_hpl, xw, cl, xl;
   112  
   113    ASSERT (n >= 1);
   114    ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n));
   115    ASSERT_MPN (rp, n);
   116    ASSERT_MPN (up, n);
   117    ASSERT_LIMB (vl);
   118  
   119    shifted_vl = vl << GMP_NAIL_BITS;
   120    cl = 0;
   121    prev_hpl = 0;
   122    do
   123      {
   124        ul = *up++;
   125        rl = *rp;
   126        umul_ppmm (hpl, lpl, ul, shifted_vl);
   127        lpl >>= GMP_NAIL_BITS;
   128        xw = rl - (prev_hpl + lpl) + cl;
   129        cl = (mp_limb_signed_t) xw >> GMP_NUMB_BITS; /* FIXME: non-portable */
   130        xl = xw & GMP_NUMB_MASK;
   131        *rp++ = xl;
   132        prev_hpl = hpl;
   133      }
   134    while (--n != 0);
   135  
   136    return prev_hpl - cl;
   137  }
   138  
   139  #endif