123 lines
3.2 KiB
NASM
123 lines
3.2 KiB
NASM
dnl IBM POWER mpn_submul_1 -- Multiply a limb vector with a limb and subtract
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dnl the result from a second limb vector.
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dnl Copyright 1992, 1994, 1999, 2000, 2001 Free Software Foundation, Inc.
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dnl This file is part of the GNU MP Library.
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dnl The GNU MP Library is free software; you can redistribute it and/or modify
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dnl it under the terms of the GNU Lesser General Public License as published
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dnl by the Free Software Foundation; either version 2.1 of the License, or (at
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dnl your option) any later version.
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dnl The GNU MP Library is distributed in the hope that it will be useful, but
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dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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dnl License for more details.
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dnl You should have received a copy of the GNU Lesser General Public License
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dnl along with the GNU MP Library; see the file COPYING.LIB. If not, write
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dnl to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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dnl Boston, MA 02110-1301, USA.
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dnl INPUT PARAMETERS
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dnl res_ptr r3
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dnl s1_ptr r4
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dnl size r5
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dnl s2_limb r6
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dnl The POWER architecture has no unsigned 32x32->64 bit multiplication
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dnl instruction. To obtain that operation, we have to use the 32x32->64
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dnl signed multiplication instruction, and add the appropriate compensation to
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dnl the high limb of the result. We add the multiplicand if the multiplier
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dnl has its most significant bit set, and we add the multiplier if the
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dnl multiplicand has its most significant bit set. We need to preserve the
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dnl carry flag between each iteration, so we have to compute the compensation
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dnl carefully (the natural, srai+and doesn't work). Since all POWER can
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dnl branch in zero cycles, we use conditional branches to for the additions.
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include(`../config.m4')
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ASM_START()
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PROLOGUE(mpn_submul_1)
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cal 3,-4(3)
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l 0,0(4)
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cmpi 0,6,0
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mtctr 5
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mul 9,0,6
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srai 7,0,31
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and 7,7,6
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mfmq 11
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cax 9,9,7
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l 7,4(3)
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sf 8,11,7 C add res_limb
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a 11,8,11 C invert cy (r11 is junk)
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blt Lneg
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Lpos: bdz Lend
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Lploop: lu 0,4(4)
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stu 8,4(3)
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cmpi 0,0,0
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mul 10,0,6
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mfmq 0
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ae 11,0,9 C low limb + old_cy_limb + old cy
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l 7,4(3)
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aze 10,10 C propagate cy to new cy_limb
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sf 8,11,7 C add res_limb
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a 11,8,11 C invert cy (r11 is junk)
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bge Lp0
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cax 10,10,6 C adjust high limb for negative limb from s1
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Lp0: bdz Lend0
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lu 0,4(4)
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stu 8,4(3)
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cmpi 0,0,0
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mul 9,0,6
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mfmq 0
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ae 11,0,10
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l 7,4(3)
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aze 9,9
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sf 8,11,7
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a 11,8,11 C invert cy (r11 is junk)
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bge Lp1
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cax 9,9,6 C adjust high limb for negative limb from s1
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Lp1: bdn Lploop
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b Lend
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Lneg: cax 9,9,0
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bdz Lend
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Lnloop: lu 0,4(4)
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stu 8,4(3)
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cmpi 0,0,0
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mul 10,0,6
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mfmq 7
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ae 11,7,9
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l 7,4(3)
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ae 10,10,0 C propagate cy to new cy_limb
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sf 8,11,7 C add res_limb
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a 11,8,11 C invert cy (r11 is junk)
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bge Ln0
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cax 10,10,6 C adjust high limb for negative limb from s1
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Ln0: bdz Lend0
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lu 0,4(4)
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stu 8,4(3)
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cmpi 0,0,0
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mul 9,0,6
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mfmq 7
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ae 11,7,10
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l 7,4(3)
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ae 9,9,0 C propagate cy to new cy_limb
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sf 8,11,7 C add res_limb
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a 11,8,11 C invert cy (r11 is junk)
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bge Ln1
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cax 9,9,6 C adjust high limb for negative limb from s1
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Ln1: bdn Lnloop
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b Lend
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Lend0: cal 9,0(10)
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Lend: st 8,4(3)
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aze 3,9
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br
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EPILOGUE(mpn_submul_1)
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