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/* IBM POWER submul_1 -- Multiply a limb vector with a limb and subtract
* the result from a second limb vector.
*
* Copyright (C) 1992, 1994, 1999, 2002 Free Software Foundation, Inc.
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include "sysdep.h"
#include "asm-syntax.h"
/*
# INPUT PARAMETERS
# res_ptr r3
# s1_ptr r4
# size r5
# s2_limb r6
# The RS/6000 has no unsigned 32x32->64 bit multiplication instruction. To
# obtain that operation, we have to use the 32x32->64 signed multiplication
# instruction, and add the appropriate compensation to the high limb of the
# result. We add the multiplicand if the multiplier has its most significant
# bit set, and we add the multiplier if the multiplicand has its most
# significant bit set. We need to preserve the carry flag between each
# iteration, so we have to compute the compensation carefully (the natural,
# srai+and doesn't work). Since the POWER architecture has a branch unit
# we can branch in zero cycles, so that's how we perform the additions.
*/
.toc
.csect ._gcry_mpih_submul_1[PR]
.align 2
.globl _gcry_mpih_submul_1
.globl ._gcry_mpih_submul_1
.csect _gcry_mpih_submul_1[DS]
_gcry_mpih_submul_1:
.long ._gcry_mpih_submul_1[PR], TOC[tc0], 0
.csect ._gcry_mpih_submul_1[PR]
._gcry_mpih_submul_1:
cal 3,-4(3)
l 0,0(4)
cmpi 0,6,0
mtctr 5
mul 9,0,6
srai 7,0,31
and 7,7,6
mfmq 11
cax 9,9,7
l 7,4(3)
sf 8,11,7 # add res_limb
a 11,8,11 # invert cy (r11 is junk)
blt Lneg
Lpos: bdz Lend
Lploop: lu 0,4(4)
stu 8,4(3)
cmpi 0,0,0
mul 10,0,6
mfmq 0
ae 11,0,9 # low limb + old_cy_limb + old cy
l 7,4(3)
aze 10,10 # propagate cy to new cy_limb
sf 8,11,7 # add res_limb
a 11,8,11 # invert cy (r11 is junk)
bge Lp0
cax 10,10,6 # adjust high limb for negative limb from s1
Lp0: bdz Lend0
lu 0,4(4)
stu 8,4(3)
cmpi 0,0,0
mul 9,0,6
mfmq 0
ae 11,0,10
l 7,4(3)
aze 9,9
sf 8,11,7
a 11,8,11 # invert cy (r11 is junk)
bge Lp1
cax 9,9,6 # adjust high limb for negative limb from s1
Lp1: bdn Lploop
b Lend
Lneg: cax 9,9,0
bdz Lend
Lnloop: lu 0,4(4)
stu 8,4(3)
cmpi 0,0,0
mul 10,0,6
mfmq 7
ae 11,7,9
l 7,4(3)
ae 10,10,0 # propagate cy to new cy_limb
sf 8,11,7 # add res_limb
a 11,8,11 # invert cy (r11 is junk)
bge Ln0
cax 10,10,6 # adjust high limb for negative limb from s1
Ln0: bdz Lend0
lu 0,4(4)
stu 8,4(3)
cmpi 0,0,0
mul 9,0,6
mfmq 7
ae 11,7,10
l 7,4(3)
ae 9,9,0 # propagate cy to new cy_limb
sf 8,11,7 # add res_limb
a 11,8,11 # invert cy (r11 is junk)
bge Ln1
cax 9,9,6 # adjust high limb for negative limb from s1
Ln1: bdn Lnloop
b Lend
Lend0: cal 9,0(10)
Lend: st 8,4(3)
aze 3,9
br
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