dnl x86 mpn_copyi -- copy limb vector, incrementing.
dnl Copyright 1999-2002 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
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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.
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dnl You should have received copies of the GNU General
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and the
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include(`../config.m4
')
C cycles/limb startup (approx)
C P5 1.0 35
C P6 0.75 45
C K6 1.0 30
C K7 1.3 65
C P4 1.0 120
C
C (Startup
time includes some function
call overheads.)
C void mpn_copyi (mp_ptr dst, mp_srcptr src, mp_size_t size)
;
C
C Copy src,size to dst,size, working from low to high addresses.
C
C The
code here is very generic
and can be expected to be reasonable on all
C the x86 family.
C
C P6 - An MMX based copy was tried, but was found to be slower than a
rep
C movs in all cases. The fastest MMX found was 0.8 cycles/limb (when
C fully aligned). A
rep movs seems to have a startup
time of about 15
C cycles, but doing something special
for small sizes could lead to a
C branch misprediction that would destroy any saving.
For now a plain
C
rep movs seems ok.
C
C K62 - We used to have a big chunk of
code doing an MMX copy at 0.56 c/l
if
C aligned
or a 1.0
rep movs
if not. But that seemed excessive since
C it only got an advantage half the
time,
and even then only showed it
C above 50 limbs
or so.
defframe(PARAM_SIZE,12)
defframe(PARAM_SRC, 8)
defframe(PARAM_DST, 4)
deflit(`FRAME
',0)
TEXT
ALIGN(32)
C
eax saved
esi
C ebx
C
ecx counter
C
edx saved
edi
C
esi src
C
edi dst
C
ebp
PROLOGUE(mpn_copyi)
movl PARAM_SIZE, %
ecx
movl %
esi, %
eax
movl PARAM_SRC, %
esi
movl %
edi, %
edx
movl PARAM_DST, %
edi
cld C better safe than sorry, see mpn/x86/README
rep
movsl
movl %
eax, %
esi
movl %
edx, %
edi
ret
EPILOGUE()
