dnl Intel Pentium-4 mpn_addlsh1_n -- mpn x+2*y.
dnl Copyright 2001-2004, 2006 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 dst!=src1,2 dst==src1 dst==src2
C P6
model 0-8,10-12 -
C P6
model 9 (Banias) ?
C P6
model 13 (Dothan) ?
C P4
model 0-1 (Willamette) ?
C P4
model 2 (Northwood) 4.25 6 6
C P4
model 3-4 (Prescott) 5 8.5 8.5
C The slightly strange combination of indexing
and pointer incrementing
C that
's used seems to work best. Not sure why, but %ecx,4 with src1 and/or
C src2 is a slowdown.
C
C The dependent chain is simply the paddq of x+2*y to the previous
carry,
C then psrlq to get the new
carry. That makes 4 c/l the target speed, which
C is almost achieved
for separate src/dst but when src==dst the write
C combining anomalies slow it down.
defframe(PARAM_SIZE, 16)
defframe(PARAM_SRC2, 12)
defframe(PARAM_SRC1, 8)
defframe(PARAM_DST, 4)
dnl re-use parameter space
define(SAVE_EBX,`PARAM_SRC1
')
TEXT
ALIGN(8)
PROLOGUE(mpn_addlsh1_n)
deflit(`FRAME
',0)
mov PARAM_SRC1, %
eax
mov %ebx, SAVE_EBX
mov PARAM_SRC2, %ebx
pxor %mm0, %mm0 C initial
carry
mov PARAM_DST, %
edx
mov PARAM_SIZE, %
ecx
lea (%
edx,%
ecx,4), %
edx C dst
end
neg %
ecx C -size
L(top):
C
eax src1
end
C ebx src2
end
C
ecx counter, limbs, negative
C
edx dst
end
C mm0
carry
movd (%ebx), %mm2
movd (%
eax), %mm1
psrlq $32, %mm0
lea 4(%
eax), %
eax
lea 4(%ebx), %ebx
psllq $1, %mm2
paddq %mm2, %mm1
paddq %mm1, %mm0
movd %mm0, (%
edx,%
ecx,4)
add $1, %
ecx
jnz L(top)
psrlq $32, %mm0
mov SAVE_EBX, %ebx
movd %mm0, %
eax
emms
ret
EPILOGUE()
