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dnl x86 mpn_copyi -- copy limb vector, incrementing.
dnl Copyright 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
dnl
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
dnl modify it under the terms of the GNU Lesser General Public License as
dnl published by the Free Software Foundation; either version 2.1 of the
dnl License, or (at your option) any later version.
dnl
dnl The GNU MP Library is distributed in the hope that it will be useful,
dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
dnl Lesser General Public License for more details.
dnl
dnl You should have received a copy of the GNU Lesser General Public
dnl License along with the GNU MP Library; see the file COPYING.LIB. If
dnl not, write to the Free Software Foundation, Inc., 51 Franklin Street,
dnl Fifth Floor, Boston, MA 02110-1301, USA.
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()
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