97 lines
2.4 KiB
NASM
97 lines
2.4 KiB
NASM
dnl Intel Pentium-4 mpn_addlsh1_n -- mpn x+2*y.
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dnl Copyright 2001, 2002, 2003, 2004 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 (approx)
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C dst!=src1,2 dst==src1 dst==src2
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C P4: 4.5 7.25 6.75
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C mp_limb_t mpn_addlsh1_n (mp_ptr dst, mp_srcptr src1, mp_srcptr src2,
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C mp_size_t size);
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C
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C The slightly strange combination of indexing and pointer incrementing
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C that's used seems to work best. Not sure why, but %ecx,4 with src1 and/or
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C src2 is a slowdown.
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C
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C The dependent chain is simply the paddq of x+2*y to the previous carry,
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C then psrlq to get the new carry. That makes 4 c/l the target speed, which
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C is almost achieved for separate src/dst but when src==dst the write
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C combining anomalies slow it down.
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defframe(PARAM_SIZE, 16)
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defframe(PARAM_SRC2, 12)
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defframe(PARAM_SRC1, 8)
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defframe(PARAM_DST, 4)
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dnl re-use parameter space
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define(SAVE_EBX,`PARAM_SRC1')
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TEXT
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ALIGN(16)
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PROLOGUE(mpn_addlsh1_n)
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deflit(`FRAME',0)
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movl PARAM_SRC1, %eax
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movl %ebx, SAVE_EBX
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movl PARAM_SRC2, %ebx
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pxor %mm0, %mm0 C initial carry
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movl PARAM_DST, %edx
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movl PARAM_SIZE, %ecx
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leal (%edx,%ecx,4), %edx C dst end
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negl %ecx C -size
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L(top):
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C eax src1 end
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C ebx src2 end
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C ecx counter, limbs, negative
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C edx dst end
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C mm0 carry
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movd (%eax), %mm1
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movd (%ebx), %mm2
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leal 4(%eax), %eax
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leal 4(%ebx), %ebx
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paddq %mm2, %mm1
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paddq %mm2, %mm1
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paddq %mm1, %mm0
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movd %mm0, (%edx,%ecx,4)
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psrlq $32, %mm0
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addl $1, %ecx
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jnz L(top)
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movl SAVE_EBX, %ebx
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movd %mm0, %eax
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emms
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ret
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EPILOGUE()
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