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/* IBM POWER rshift
*
* 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
# s_ptr r4
# size r5
# cnt r6
*/
.toc
.extern _gcry_mpih_rshift[DS]
.extern ._gcry_mpih_rshift
.csect [PR]
.align 2
.globl _gcry_mpih_rshift
.globl ._gcry_mpih_rshift
.csect _gcry_mpih_rshift[DS]
_gcry_mpih_rshift:
.long ._gcry_mpih_rshift, TOC[tc0], 0
.csect [PR]
._gcry_mpih_rshift:
sfi 8,6,32
mtctr 5 # put limb count in CTR loop register
l 0,0(4) # read least significant limb
ai 9,3,-4 # adjust res_ptr since it's offset in the stu:s
sle 3,0,8 # compute carry limb, and init MQ register
bdz Lend2 # if just one limb, skip loop
lu 0,4(4) # read 2:nd least significant limb
sleq 7,0,8 # compute least significant limb of result
bdz Lend # if just two limb, skip loop
Loop: lu 0,4(4) # load next higher limb
stu 7,4(9) # store previous result during read latency
sleq 7,0,8 # compute result limb
bdn Loop # loop back until CTR is zero
Lend: stu 7,4(9) # store 2:nd most significant limb
Lend2: sre 7,0,6 # compute most significant limb
st 7,4(9) # store it
br
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