91 lines
2.5 KiB
NASM
91 lines
2.5 KiB
NASM
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dnl x86 mpn_copyi -- copy limb vector, incrementing.
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dnl Copyright 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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dnl
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dnl This file is part of the GNU MP Library.
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dnl
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dnl The GNU MP Library is free software; you can redistribute it and/or
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dnl modify it under the terms of the GNU Lesser General Public License as
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dnl published by the Free Software Foundation; either version 2.1 of the
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dnl License, or (at your option) any later version.
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dnl
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dnl The GNU MP Library is distributed in the hope that it will be useful,
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dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
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dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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dnl Lesser General Public License for more details.
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dnl
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dnl You should have received a copy of the GNU Lesser General Public
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dnl License along with the GNU MP Library; see the file COPYING.LIB. If
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dnl not, write to the Free Software Foundation, Inc., 51 Franklin Street,
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dnl Fifth Floor, Boston, MA 02110-1301, USA.
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include(`../config.m4')
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C cycles/limb startup (approx)
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C P5: 1.0 35
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C P6 0.75 45
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C K6 1.0 30
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C K7: 1.3 65
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C P4: 1.0 120
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C
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C (Startup time includes some function call overheads.)
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C void mpn_copyi (mp_ptr dst, mp_srcptr src, mp_size_t size);
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C
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C Copy src,size to dst,size, working from low to high addresses.
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C
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C The code here is very generic and can be expected to be reasonable on all
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C the x86 family.
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C
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C P6 - An MMX based copy was tried, but was found to be slower than a rep
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C movs in all cases. The fastest MMX found was 0.8 cycles/limb (when
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C fully aligned). A rep movs seems to have a startup time of about 15
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C cycles, but doing something special for small sizes could lead to a
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C branch misprediction that would destroy any saving. For now a plain
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C rep movs seems ok.
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C
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C K62 - We used to have a big chunk of code doing an MMX copy at 0.56 c/l if
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C aligned or a 1.0 rep movs if not. But that seemed excessive since
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C it only got an advantage half the time, and even then only showed it
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C above 50 limbs or so.
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defframe(PARAM_SIZE,12)
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defframe(PARAM_SRC, 8)
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defframe(PARAM_DST, 4)
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deflit(`FRAME',0)
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TEXT
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ALIGN(32)
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C eax saved esi
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C ebx
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C ecx counter
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C edx saved edi
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C esi src
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C edi dst
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C ebp
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PROLOGUE(mpn_copyi)
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movl PARAM_SIZE, %ecx
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movl %esi, %eax
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movl PARAM_SRC, %esi
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movl %edi, %edx
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movl PARAM_DST, %edi
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cld C better safe than sorry, see mpn/x86/README
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rep
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movsl
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movl %eax, %esi
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movl %edx, %edi
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ret
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EPILOGUE()
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