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

     1  /* mpn_rshift -- Shift right low level for Cray vector processors.
     2  
     3  Copyright (C) 2000 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 <intrinsics.h>
    32  #include "gmp.h"
    33  #include "gmp-impl.h"
    34  
    35  mp_limb_t
    36  mpn_rshift (mp_ptr wp, mp_srcptr up, mp_size_t n, unsigned int cnt)
    37  {
    38    unsigned sh_1, sh_2;
    39    mp_size_t i;
    40    mp_limb_t retval;
    41  
    42    sh_1 = cnt;
    43    sh_2 = GMP_LIMB_BITS - sh_1;
    44    retval = up[0] << sh_2;
    45  
    46  #pragma _CRI ivdep
    47    for (i = 0; i < n - 1; i++)
    48      {
    49  #if 1
    50        wp[i] = (up[i] >> sh_1) | (up[i + 1] << sh_2);
    51  #else
    52        /* This is the recommended way, but at least on SV1 it is slower.  */
    53        wp[i] = _dshiftr (up[i + 1], up[i], sh_1);
    54  #endif
    55      }
    56  
    57    wp[n - 1] = up[n - 1] >> sh_1;
    58    return retval;
    59  }