mpir/mpn/x86/pentium4/copyd.asm

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dnl Pentium-4 mpn_copyd -- copy limb vector, decrementing.
dnl
dnl Copyright 1999, 2000, 2001 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.
dnl The std/rep/movsl/cld is very slow for small blocks on pentium4. Its
dnl startup time seems to be about 165 cycles. It then needs 2.6 c/l.
dnl We therefore use an open-coded 2 c/l copying loop.
dnl Ultimately, we may want to use 64-bit movq or 128-bit movdqu in some
dnl nifty unrolled arrangement. Clearly, that could reach much higher
dnl speeds, at least for large blocks.
include(`../config.m4')
defframe(PARAM_SIZE, 12)
defframe(PARAM_SRC, 8)
defframe(PARAM_DST, 4)
TEXT
ALIGN(8)
PROLOGUE(mpn_copyd)
deflit(`FRAME',0)
movl PARAM_SIZE, %ecx
movl PARAM_SRC, %eax
movl PARAM_DST, %edx
movl %ebx, PARAM_SIZE
addl $-1, %ecx
js L(end)
L(loop):
movl (%eax,%ecx,4), %ebx
movl %ebx, (%edx,%ecx,4)
addl $-1, %ecx
jns L(loop)
L(end):
movl PARAM_SIZE, %ebx
ret
EPILOGUE()