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dnl Pentium-4 mpn_copyd -- copy limb vector, decrementing.
dnl Copyright 1999-2001 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/.
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()
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