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/* alpha - left shift
*
* Copyright (C) 1994, 1995, 1998, 2001 Free Software Foundation, Inc.
*
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GnuPG 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* Note: This code is heavily based on the GNU MP Library.
* Actually it's the same code with only minor changes in the
* way the data is stored; this is to support the abstraction
* of an optional secure memory allocation which may be used
* to avoid revealing of sensitive data due to paging etc.
* The GNU MP Library itself is published under the LGPL;
* however I decided to publish this code under the plain GPL.
*/
/*******************
* mpi_limb_t
* mpihelp_lshift( mpi_ptr_t wp, (r16)
* mpi_ptr_t up, (r17)
* mpi_size_t usize, (r18)
* unsigned cnt) (r19)
*
* This code runs at 4.8 cycles/limb on the 21064. With infinite unrolling,
* it would take 4 cycles/limb. It should be possible to get down to 3
* cycles/limb since both ldq and stq can be paired with the other used
* instructions. But there are many restrictions in the 21064 pipeline that
* makes it hard, if not impossible, to get down to 3 cycles/limb:
*
* 1. ldq has a 3 cycle delay, srl and sll have a 2 cycle delay.
* 2. Only aligned instruction pairs can be paired.
* 3. The store buffer or silo might not be able to deal with the bandwidth.
*/
.set noreorder
.set noat
.text
.align 3
.globl mpihelp_lshift
.ent mpihelp_lshift
mpihelp_lshift:
.frame $30,0,$26,0
s8addq $18,$17,$17 # make r17 point at end of s1
ldq $4,-8($17) # load first limb
subq $17,8,$17
subq $31,$19,$7
s8addq $18,$16,$16 # make r16 point at end of RES
subq $18,1,$18
and $18,4-1,$20 # number of limbs in first loop
srl $4,$7,$0 # compute function result
beq $20,.L0
subq $18,$20,$18
.align 3
.Loop0:
ldq $3,-8($17)
subq $16,8,$16
subq $17,8,$17
subq $20,1,$20
sll $4,$19,$5
srl $3,$7,$6
bis $3,$3,$4
bis $5,$6,$8
stq $8,0($16)
bne $20,.Loop0
.L0: beq $18,.Lend
.align 3
.Loop: ldq $3,-8($17)
subq $16,32,$16
subq $18,4,$18
sll $4,$19,$5
srl $3,$7,$6
ldq $4,-16($17)
sll $3,$19,$1
bis $5,$6,$8
stq $8,24($16)
srl $4,$7,$2
ldq $3,-24($17)
sll $4,$19,$5
bis $1,$2,$8
stq $8,16($16)
srl $3,$7,$6
ldq $4,-32($17)
sll $3,$19,$1
bis $5,$6,$8
stq $8,8($16)
srl $4,$7,$2
subq $17,32,$17
bis $1,$2,$8
stq $8,0($16)
bgt $18,.Loop
.Lend: sll $4,$19,$8
stq $8,-8($16)
ret $31,($26),1
.end mpihelp_lshift
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