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113 lines
2.9 KiB
ArmAsm
113 lines
2.9 KiB
ArmAsm
;! HP-PA-1.1 __mpn_submul_1 -- Multiply a limb vector with a limb and
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;! subtract the result from a second limb vector.
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;! Copyright (C) 1992-2023 Free Software Foundation, Inc.
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;! This file is part of the GNU MP Library.
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;! The GNU MP Library is free software; you can redistribute it and/or modify
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;! it under the terms of the GNU Lesser General Public License as published by
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;! the Free Software Foundation; either version 2.1 of the License, or (at your
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;! option) any later version.
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;! The GNU MP Library is distributed in the hope that it will be useful, but
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;! WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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;! or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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;! License for more details.
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;! You should have received a copy of the GNU Lesser General Public License
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;! along with the GNU MP Library. If not, see
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;! <https://www.gnu.org/licenses/>.
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;! INPUT PARAMETERS
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;! res_ptr r26
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;! s1_ptr r25
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;! size r24
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;! s2_limb r23
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;! This runs at 12 cycles/limb on a PA7000. With the used instructions, it
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;! can not become faster due to data cache contention after a store. On the
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;! PA7100 it runs at 11 cycles/limb, and that can not be improved either,
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;! since only the xmpyu does not need the integer pipeline, so the only
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;! dual-issue we will get are addc+xmpyu. Unrolling could gain a cycle/limb
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;! on the PA7100.
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;! There are some ideas described in mul_1.s that applies to this code too.
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;! It seems possible to make this run as fast as __mpn_addmul_1, if we use
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;! sub,>>= %r29,%r20,%r22
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;! addi 1,%r28,%r28
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;! but that requires reworking the hairy software pipeline...
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.text
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.export __mpn_submul_1
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__mpn_submul_1:
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.proc
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.callinfo frame=64,no_calls
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.entry
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ldo 64(%r30),%r30
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fldws,ma 4(%r25),%fr5
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stw %r23,-16(%r30) ;! move s2_limb ...
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addib,= -1,%r24,L$just_one_limb
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fldws -16(%r30),%fr4 ;! ... into fr4
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add %r0,%r0,%r0 ;! clear carry
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xmpyu %fr4,%fr5,%fr6
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fldws,ma 4(%r25),%fr7
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fstds %fr6,-16(%r30)
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xmpyu %fr4,%fr7,%fr8
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ldw -12(%r30),%r20 ;! least significant limb in product
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ldw -16(%r30),%r28
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fstds %fr8,-16(%r30)
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addib,= -1,%r24,L$end
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ldw -12(%r30),%r1
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;! Main loop
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L$loop:
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ldws 0(%r26),%r29
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fldws,ma 4(%r25),%fr5
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sub %r29,%r20,%r22
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add %r22,%r20,%r0
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stws,ma %r22,4(%r26)
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addc %r28,%r1,%r20
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xmpyu %fr4,%fr5,%fr6
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ldw -16(%r30),%r28
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fstds %fr6,-16(%r30)
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addc %r0,%r28,%r28
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addib,<> -1,%r24,L$loop
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ldw -12(%r30),%r1
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L$end:
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ldw 0(%r26),%r29
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sub %r29,%r20,%r22
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add %r22,%r20,%r0
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stws,ma %r22,4(%r26)
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addc %r28,%r1,%r20
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ldw -16(%r30),%r28
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ldws 0(%r26),%r29
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addc %r0,%r28,%r28
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sub %r29,%r20,%r22
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add %r22,%r20,%r0
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stws,ma %r22,4(%r26)
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addc %r0,%r28,%r28
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bv 0(%r2)
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ldo -64(%r30),%r30
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L$just_one_limb:
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xmpyu %fr4,%fr5,%fr6
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ldw 0(%r26),%r29
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fstds %fr6,-16(%r30)
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ldw -12(%r30),%r1
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ldw -16(%r30),%r28
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sub %r29,%r1,%r22
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add %r22,%r1,%r0
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stw %r22,0(%r26)
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addc %r0,%r28,%r28
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bv 0(%r2)
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ldo -64(%r30),%r30
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.exit
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.procend
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