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dnl AMD K7 mpn_mod_34lsub1 -- remainder modulo 2^24-1.
dnl Copyright 2000-2002, 2004, 2005, 2008 Free Software Foundation, Inc.
dnl This file is part of the GNU MP Library.
dnl
dnl The GNU MP Library is free software; you can redistribute it and/or modify
dnl it under the terms of either:
dnl
dnl * the GNU Lesser General Public License as published by the Free
dnl Software Foundation; either version 3 of the License, or (at your
dnl option) any later version.
dnl
dnl or
dnl
dnl * the GNU General Public License as published by the Free Software
dnl Foundation; either version 2 of the License, or (at your option) any
dnl later version.
dnl
dnl or both in parallel, as here.
dnl
dnl The GNU MP Library is distributed in the hope that it will be useful, but
dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
dnl for more details.
dnl
dnl You should have received copies of the GNU General Public License and the
dnl GNU Lesser General Public License along with the GNU MP Library. If not,
dnl see https://www.gnu.org/licenses/.
include(`../config.m4')
C cycles/limb
C Athlon: 1
C Hammer: 1
C mp_limb_t mpn_mod_34lsub1 (mp_srcptr src, mp_size_t size)
C
C The loop form below and the 64 byte code alignment seem necessary for the
C claimed speed. This is a bit strange, since normally k7 isn't very
C sensitive to such things. Perhaps there has to be 6 instructions in the
C first 16 bytes for the BTB entry or something.
defframe(PARAM_SIZE, 8)
defframe(PARAM_SRC, 4)
dnl re-use parameter space
define(SAVE_EDI, `PARAM_SIZE')
TEXT
ALIGN(64)
PROLOGUE(mpn_mod_34lsub1)
deflit(`FRAME',0)
movl PARAM_SIZE, %ecx
movl PARAM_SRC, %edx
subl $2, %ecx
ja L(three_or_more)
movl (%edx), %eax
jb L(one)
movl 4(%edx), %ecx
movl %eax, %edx
shrl $24, %eax C src[0] low
andl $0xFFFFFF, %edx C src[0] high
addl %edx, %eax
movl %ecx, %edx
andl $0xFFFF, %ecx
shrl $16, %edx C src[1] high
addl %edx, %eax
shll $8, %ecx C src[1] low
addl %ecx, %eax
L(one):
ret
L(three_or_more):
C eax
C ebx
C ecx size-2
C edx src
C esi
C edi
pushl %ebx FRAME_pushl()
xorl %eax, %eax
xorl %ebx, %ebx
movl %edi, SAVE_EDI
pushl %esi FRAME_pushl()
xorl %esi, %esi C and clear carry flag
C code offset 0x40 at this point
L(top):
C eax acc 0mod3
C ebx acc 1mod3
C ecx counter, limbs
C edx src
C esi acc 2mod3
C edi
leal 24(%edx), %edx
leal -2(%ecx), %ecx
adcl -24(%edx), %eax
adcl -20(%edx), %ebx
adcl -16(%edx), %esi
decl %ecx
jng L(done_loop)
leal -2(%ecx), %ecx
adcl -12(%edx), %eax
adcl -8(%edx), %ebx
adcl -4(%edx), %esi
decl %ecx
jg L(top)
leal 12(%edx), %edx
L(done_loop):
C ecx is -2, -1 or 0 representing 0, 1 or 2 more limbs, respectively
incl %ecx
movl $0xFFFFFFFF, %edi
js L(combine)
adcl -12(%edx), %eax
decl %ecx
movl $0xFFFFFF00, %edi
js L(combine)
adcl -8(%edx), %ebx
movl $0xFFFF0000, %edi
L(combine):
C eax acc 0mod3
C ebx acc 1mod3
C ecx
C edx
C esi acc 2mod3
C edi mask
sbbl %ecx, %ecx C carry
movl %eax, %edx C 0mod3
shrl $24, %eax C 0mod3 high
andl %edi, %ecx C carry masked
andl $0x00FFFFFF, %edx C 0mod3 low
movl %ebx, %edi C 1mod3
subl %ecx, %eax C apply carry
shrl $16, %ebx C 1mod3 high
andl $0xFFFF, %edi
addl %edx, %eax C apply 0mod3 low
movl %esi, %edx C 2mod3
shll $8, %edi C 1mod3 low
addl %ebx, %eax C apply 1mod3 high
shrl $8, %esi C 2mod3 high
movzbl %dl, %edx C 2mod3 low
addl %edi, %eax C apply 1mod3 low
shll $16, %edx C 2mod3 low
addl %esi, %eax C apply 2mod3 high
popl %esi FRAME_popl()
movl SAVE_EDI, %edi
addl %edx, %eax C apply 2mod3 low
popl %ebx FRAME_popl()
ret
EPILOGUE()
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