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dnl Intel P6 mpn_modexact_1_odd -- exact division style remainder.
dnl Copyright 2000-2002, 2007 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 P6: 10.0 cycles/limb
C mp_limb_t mpn_modexact_1_odd (mp_srcptr src, mp_size_t size,
C mp_limb_t divisor);
C mp_limb_t mpn_modexact_1c_odd (mp_srcptr src, mp_size_t size,
C mp_limb_t divisor, mp_limb_t carry);
C
C It's not worth skipping a step at the end when high<divisor since the main
C loop is only 10 cycles.
defframe(PARAM_CARRY, 16)
defframe(PARAM_DIVISOR,12)
defframe(PARAM_SIZE, 8)
defframe(PARAM_SRC, 4)
dnl Not enough room under modexact_1 to make these re-use the parameter
dnl space, unfortunately.
defframe(SAVE_EBX, -4)
defframe(SAVE_ESI, -8)
defframe(SAVE_EDI, -12)
deflit(STACK_SPACE, 12)
TEXT
ALIGN(16)
PROLOGUE(mpn_modexact_1c_odd)
deflit(`FRAME',0)
movl PARAM_CARRY, %ecx
jmp L(start_1c)
EPILOGUE()
ALIGN(16)
PROLOGUE(mpn_modexact_1_odd)
deflit(`FRAME',0)
xorl %ecx, %ecx
L(start_1c):
movl PARAM_DIVISOR, %eax
subl $STACK_SPACE, %esp FRAME_subl_esp(STACK_SPACE)
movl %esi, SAVE_ESI
movl PARAM_SRC, %esi
shrl %eax C d/2
movl %edi, SAVE_EDI
andl $127, %eax
ifdef(`PIC',`
LEA( binvert_limb_table, %edi)
movzbl (%eax,%edi), %edi C inv 8 bits
',`
movzbl binvert_limb_table(%eax), %edi C inv 8 bits
')
xorl %edx, %edx C initial extra carry
leal (%edi,%edi), %eax C 2*inv
imull %edi, %edi C inv*inv
movl %ebx, SAVE_EBX
movl PARAM_SIZE, %ebx
imull PARAM_DIVISOR, %edi C inv*inv*d
subl %edi, %eax C inv = 2*inv - inv*inv*d
leal (%eax,%eax), %edi C 2*inv
imull %eax, %eax C inv*inv
imull PARAM_DIVISOR, %eax C inv*inv*d
leal (%esi,%ebx,4), %esi C src end
negl %ebx C -size
subl %eax, %edi C inv = 2*inv - inv*inv*d
ASSERT(e,` C d*inv == 1 mod 2^GMP_LIMB_BITS
movl PARAM_DIVISOR, %eax
imull %edi, %eax
cmpl $1, %eax')
C The dependent chain here is
C
C subl %edx, %eax 1
C imull %edi, %eax 4
C mull PARAM_DIVISOR 5
C ----
C total 10
C
C and this is the measured speed. No special scheduling is necessary, out
C of order execution hides the load latency.
L(top):
C eax scratch (src limb)
C ebx counter, limbs, negative
C ecx carry bit, 0 or 1
C edx carry limb, high of last product
C esi &src[size]
C edi inverse
C ebp
movl (%esi,%ebx,4), %eax
subl %ecx, %eax
sbbl %ecx, %ecx
subl %edx, %eax
sbbl $0, %ecx
imull %edi, %eax
negl %ecx
mull PARAM_DIVISOR
incl %ebx
jnz L(top)
movl SAVE_ESI, %esi
leal (%ecx,%edx), %eax
movl SAVE_EDI, %edi
movl SAVE_EBX, %ebx
addl $STACK_SPACE, %esp
ret
EPILOGUE()
ASM_END()
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