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

     1  /* Cray PVP/IEEE mpn_mul_basecase.
     2  
     3  Copyright 2000, 2001 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  /* The most critical loop of this code runs at about 5 cycles/limb on a T90.
    32     That is not perfect, mainly due to vector register shortage.  */
    33  
    34  #include <intrinsics.h>
    35  #include "gmp.h"
    36  #include "gmp-impl.h"
    37  
    38  void
    39  mpn_mul_basecase (mp_ptr rp,
    40  		  mp_srcptr up, mp_size_t un,
    41  		  mp_srcptr vp, mp_size_t vn)
    42  {
    43    mp_limb_t cy[un + vn];
    44    mp_limb_t vl;
    45    mp_limb_t a, b, r, s0, s1, c0, c1;
    46    mp_size_t i, j;
    47    int more_carries;
    48  
    49    for (i = 0; i < un + vn; i++)
    50      {
    51        rp[i] = 0;
    52        cy[i] = 0;
    53      }
    54  
    55  #pragma _CRI novector
    56    for (j = 0; j < vn; j++)
    57      {
    58        vl = vp[j];
    59  
    60        a = up[0] * vl;
    61        r = rp[j];
    62        s0 = a + r;
    63        rp[j] = s0;
    64        c0 = ((a & r) | ((a | r) & ~s0)) >> 63;
    65        cy[j] += c0;
    66  
    67  #pragma _CRI ivdep
    68        for (i = 1; i < un; i++)
    69  	{
    70  	  a = up[i] * vl;
    71  	  b = _int_mult_upper (up[i - 1], vl);
    72  	  s0 = a + b;
    73  	  c0 = ((a & b) | ((a | b) & ~s0)) >> 63;
    74  	  r = rp[j + i];
    75  	  s1 = s0 + r;
    76  	  rp[j + i] = s1;
    77  	  c1 = ((s0 & r) | ((s0 | r) & ~s1)) >> 63;
    78  	  cy[j + i] += c0 + c1;
    79  	}
    80        rp[j + un] = _int_mult_upper (up[un - 1], vl);
    81      }
    82  
    83    more_carries = 0;
    84  #pragma _CRI ivdep
    85    for (i = 1; i < un + vn; i++)
    86      {
    87        r = rp[i];
    88        c0 = cy[i - 1];
    89        s0 = r + c0;
    90        rp[i] = s0;
    91        c0 = (r & ~s0) >> 63;
    92        more_carries += c0;
    93      }
    94    /* If that second loop generated carry, handle that in scalar loop.  */
    95    if (more_carries)
    96      {
    97        mp_limb_t cyrec = 0;
    98        for (i = 1; i < un + vn; i++)
    99  	{
   100  	  r = rp[i];
   101  	  c0 = (r < cy[i - 1]);
   102  	  s0 = r + cyrec;
   103  	  rp[i] = s0;
   104  	  c1 = (r & ~s0) >> 63;
   105  	  cyrec = c0 | c1;
   106  	}
   107      }
   108  }