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; HP-PA-1.1 __mpn_submul_1 -- Multiply a limb vector with a limb and
; subtract the result from a second limb vector.
; Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
; This file is part of the GNU MP Library.
; The GNU MP Library is free software; you can redistribute it and/or modify
; it under the terms of the GNU Library General Public License as published by
; the Free Software Foundation; either version 2 of the License, or (at your
; option) any later version.
; The GNU MP Library 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 Library General Public
; License for more details.
; You should have received a copy of the GNU Library General Public License
; along with the GNU MP Library; see the file COPYING.LIB. If not, write to
; the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
; MA 02111-1307, USA.
; INPUT PARAMETERS
; res_ptr r26
; s1_ptr r25
; size r24
; s2_limb r23
; This runs at 12 cycles/limb on a PA7000. With the used instructions, it
; can not become faster due to data cache contention after a store. On the
; PA7100 it runs at 11 cycles/limb, and that can not be improved either,
; since only the xmpyu does not need the integer pipeline, so the only
; dual-issue we will get are addc+xmpyu. Unrolling could gain a cycle/limb
; on the PA7100.
; There are some ideas described in mul_1.s that applies to this code too.
; It seems possible to make this run as fast as __mpn_addmul_1, if we use
; sub,>>= %r29,%r19,%r22
; addi 1,%r28,%r28
; but that requires reworking the hairy software pipeline...
.code
.export __mpn_submul_1
__mpn_submul_1
.proc
.callinfo frame=64,no_calls
.entry
ldo 64(%r30),%r30
fldws,ma 4(%r25),%fr5
stw %r23,-16(%r30) ; move s2_limb ...
addib,= -1,%r24,L$just_one_limb
fldws -16(%r30),%fr4 ; ... into fr4
add %r0,%r0,%r0 ; clear carry
xmpyu %fr4,%fr5,%fr6
fldws,ma 4(%r25),%fr7
fstds %fr6,-16(%r30)
xmpyu %fr4,%fr7,%fr8
ldw -12(%r30),%r19 ; least significant limb in product
ldw -16(%r30),%r28
fstds %fr8,-16(%r30)
addib,= -1,%r24,L$end
ldw -12(%r30),%r1
; Main loop
L$loop ldws 0(%r26),%r29
fldws,ma 4(%r25),%fr5
sub %r29,%r19,%r22
add %r22,%r19,%r0
stws,ma %r22,4(%r26)
addc %r28,%r1,%r19
xmpyu %fr4,%fr5,%fr6
ldw -16(%r30),%r28
fstds %fr6,-16(%r30)
addc %r0,%r28,%r28
addib,<> -1,%r24,L$loop
ldw -12(%r30),%r1
L$end ldw 0(%r26),%r29
sub %r29,%r19,%r22
add %r22,%r19,%r0
stws,ma %r22,4(%r26)
addc %r28,%r1,%r19
ldw -16(%r30),%r28
ldws 0(%r26),%r29
addc %r0,%r28,%r28
sub %r29,%r19,%r22
add %r22,%r19,%r0
stws,ma %r22,4(%r26)
addc %r0,%r28,%r28
bv 0(%r2)
ldo -64(%r30),%r30
L$just_one_limb
xmpyu %fr4,%fr5,%fr6
ldw 0(%r26),%r29
fstds %fr6,-16(%r30)
ldw -12(%r30),%r1
ldw -16(%r30),%r28
sub %r29,%r1,%r22
add %r22,%r1,%r0
stw %r22,0(%r26)
addc %r0,%r28,%r28
bv 0(%r2)
ldo -64(%r30),%r30
.exit
.procend
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