source/libs/gmp/gmp-src/mpn/power/submul_1.asm

   1 dnl  IBM POWER mpn_submul_1 -- Multiply a limb vector with a limb and subtract
   2 dnl  the result from a second limb vector.
   3
   4 dnl  Copyright 1992, 1994, 1999-2001 Free Software Foundation, Inc.
   5
   6 dnl  This file is part of the GNU MP Library.
   7 dnl
   8 dnl  The GNU MP Library is free software; you can redistribute it and/or modify
   9 dnl  it under the terms of either:
  10 dnl
  11 dnl    * the GNU Lesser General Public License as published by the Free
  12 dnl      Software Foundation; either version 3 of the License, or (at your
  13 dnl      option) any later version.
  14 dnl
  15 dnl  or
  16 dnl
  17 dnl    * the GNU General Public License as published by the Free Software
  18 dnl      Foundation; either version 2 of the License, or (at your option) any
  19 dnl      later version.
  20 dnl
  21 dnl  or both in parallel, as here.
  22 dnl
  23 dnl  The GNU MP Library is distributed in the hope that it will be useful, but
  24 dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  25 dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  26 dnl  for more details.
  27 dnl
  28 dnl  You should have received copies of the GNU General Public License and the
  29 dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
  30 dnl  see https://www.gnu.org/licenses/.
  31
  32
  33 dnl  INPUT PARAMETERS
  34 dnl  res_ptr    r3
  35 dnl  s1_ptr     r4
  36 dnl  size       r5
  37 dnl  s2_limb    r6
  38
  39 dnl  The POWER architecture has no unsigned 32x32->64 bit multiplication
  40 dnl  instruction.  To obtain that operation, we have to use the 32x32->64
  41 dnl  signed multiplication instruction, and add the appropriate compensation to
  42 dnl  the high limb of the result.  We add the multiplicand if the multiplier
  43 dnl  has its most significant bit set, and we add the multiplier if the
  44 dnl  multiplicand has its most significant bit set.  We need to preserve the
  45 dnl  carry flag between each iteration, so we have to compute the compensation
  46 dnl  carefully (the natural, srai+and doesn't work).  Since all POWER can
  47 dnl  branch in zero cycles, we use conditional branches for the compensation.
  48
  49 include(`../config.m4')
  50
  51 ASM_START()
  52 PROLOGUE(mpn_submul_1)
  53         cal     3,-4(3)
  54         l       0,0(4)
  55         cmpi    0,6,0
  56         mtctr   5
  57         mul     9,0,6
  58         srai    7,0,31
  59         and     7,7,6
  60         mfmq    11
  61         cax     9,9,7
  62         l       7,4(3)
  63         sf      8,11,7          C add res_limb
  64         a       11,8,11         C invert cy (r11 is junk)
  65         blt     Lneg
  66 Lpos:   bdz     Lend
  67
  68 Lploop: lu      0,4(4)
  69         stu     8,4(3)
  70         cmpi    0,0,0
  71         mul     10,0,6
  72         mfmq    0
  73         ae      11,0,9          C low limb + old_cy_limb + old cy
  74         l       7,4(3)
  75         aze     10,10           C propagate cy to new cy_limb
  76         sf      8,11,7          C add res_limb
  77         a       11,8,11         C invert cy (r11 is junk)
  78         bge     Lp0
  79         cax     10,10,6         C adjust high limb for negative limb from s1
  80 Lp0:    bdz     Lend0
  81         lu      0,4(4)
  82         stu     8,4(3)
  83         cmpi    0,0,0
  84         mul     9,0,6
  85         mfmq    0
  86         ae      11,0,10
  87         l       7,4(3)
  88         aze     9,9
  89         sf      8,11,7
  90         a       11,8,11         C invert cy (r11 is junk)
  91         bge     Lp1
  92         cax     9,9,6           C adjust high limb for negative limb from s1
  93 Lp1:    bdn     Lploop
  94
  95         b       Lend
  96
  97 Lneg:   cax     9,9,0
  98         bdz     Lend
  99 Lnloop: lu      0,4(4)
 100         stu     8,4(3)
 101         cmpi    0,0,0
 102         mul     10,0,6
 103         mfmq    7
 104         ae      11,7,9
 105         l       7,4(3)
 106         ae      10,10,0         C propagate cy to new cy_limb
 107         sf      8,11,7          C add res_limb
 108         a       11,8,11         C invert cy (r11 is junk)
 109         bge     Ln0
 110         cax     10,10,6         C adjust high limb for negative limb from s1
 111 Ln0:    bdz     Lend0
 112         lu      0,4(4)
 113         stu     8,4(3)
 114         cmpi    0,0,0
 115         mul     9,0,6
 116         mfmq    7
 117         ae      11,7,10
 118         l       7,4(3)
 119         ae      9,9,0           C propagate cy to new cy_limb
 120         sf      8,11,7          C add res_limb
 121         a       11,8,11         C invert cy (r11 is junk)
 122         bge     Ln1
 123         cax     9,9,6           C adjust high limb for negative limb from s1
 124 Ln1:    bdn     Lnloop
 125         b       Lend
 126
 127 Lend0:  cal     9,0(10)
 128 Lend:   st      8,4(3)
 129         aze     3,9
 130         br
 131 EPILOGUE(mpn_submul_1)