addlsh1_n.asm
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上传日期:2022-08-06
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- dnl Intel Pentium-4 mpn_addlsh1_n -- mpn x+2*y.
- dnl Copyright 2001, 2002, 2003, 2004, 2006 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 3 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 License
- dnl along with the GNU MP Library. If not, see http://www.gnu.org/licenses/.
- include(`../config.m4')
- C cycles/limb (approx)
- C dst!=src1,2 dst==src1 dst==src2
- C P4 m2: 4.5 ?7.25 ?6.75
- C P4 m3: 5.3 ? ?
- C mp_limb_t mpn_addlsh1_n (mp_ptr dst, mp_srcptr src1, mp_srcptr src2,
- C mp_size_t size);
- C
- C The slightly strange combination of indexing and pointer incrementing
- C that's used seems to work best. Not sure why, but %ecx,4 with src1 and/or
- C src2 is a slowdown.
- C
- C The dependent chain is simply the paddq of x+2*y to the previous carry,
- C then psrlq to get the new carry. That makes 4 c/l the target speed, which
- C is almost achieved for separate src/dst but when src==dst the write
- C combining anomalies slow it down.
- defframe(PARAM_SIZE, 16)
- defframe(PARAM_SRC2, 12)
- defframe(PARAM_SRC1, 8)
- defframe(PARAM_DST, 4)
- dnl re-use parameter space
- define(SAVE_EBX,`PARAM_SRC1')
- TEXT
- ALIGN(8)
- PROLOGUE(mpn_addlsh1_n)
- deflit(`FRAME',0)
- movl PARAM_SRC1, %eax
- movl %ebx, SAVE_EBX
- movl PARAM_SRC2, %ebx
- pxor %mm0, %mm0 C initial carry
- movl PARAM_DST, %edx
- movl PARAM_SIZE, %ecx
- leal (%edx,%ecx,4), %edx C dst end
- negl %ecx C -size
- L(top):
- C eax src1 end
- C ebx src2 end
- C ecx counter, limbs, negative
- C edx dst end
- C mm0 carry
- movd (%eax), %mm1
- movd (%ebx), %mm2
- psrlq $32, %mm0
- leal 4(%eax), %eax
- leal 4(%ebx), %ebx
- paddq %mm2, %mm1
- paddq %mm2, %mm1
- paddq %mm1, %mm0
- movd %mm0, (%edx,%ecx,4)
- addl $1, %ecx
- jnz L(top)
- psrlq $32, %mm0
- movl SAVE_EBX, %ebx
- movd %mm0, %eax
- emms
- ret
- EPILOGUE()