mul_2.asm
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上传日期:2022-08-06
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- dnl Intel Pentium mpn_mul_2 -- mpn by 2-limb multiplication.
- dnl Copyright 2001, 2002 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 P5: 24.0 cycles/limb
- C mp_limb_t mpn_mul_2 (mp_ptr dst, mp_srcptr src, mp_size_t size,
- C mp_srcptr mult);
- C
- C At 24 c/l this is only 2 cycles faster than a separate mul_1 and addmul_1,
- C but has the advantage of making just one pass over the operands.
- C
- C There's not enough registers to use PARAM_MULT directly, so the multiplier
- C limbs are transferred to local variables on the stack.
- defframe(PARAM_MULT, 16)
- defframe(PARAM_SIZE, 12)
- defframe(PARAM_SRC, 8)
- defframe(PARAM_DST, 4)
- dnl re-use parameter space
- define(VAR_MULT_LOW, `PARAM_SRC')
- define(VAR_MULT_HIGH,`PARAM_DST')
- TEXT
- ALIGN(8)
- PROLOGUE(mpn_mul_2)
- deflit(`FRAME',0)
- pushl %esi FRAME_pushl()
- pushl %edi FRAME_pushl()
- movl PARAM_SRC, %esi
- movl PARAM_DST, %edi
- movl PARAM_MULT, %eax
- movl PARAM_SIZE, %ecx
- movl 4(%eax), %edx C mult high
- movl (%eax), %eax C mult low
- movl %eax, VAR_MULT_LOW
- movl %edx, VAR_MULT_HIGH
- pushl %ebx FRAME_pushl()
- pushl %ebp FRAME_pushl()
- mull (%esi) C src[0] * mult[0]
- movl %eax, %ebp C in case src==dst
- movl (%esi), %eax C src[0]
- movl %ebp, (%edi) C dst[0]
- movl %edx, %ebx C initial low carry
- xorl %ebp, %ebp C initial high carry
- leal (%edi,%ecx,4), %edi C dst end
- mull VAR_MULT_HIGH C src[0] * mult[1]
- subl $2, %ecx C size-2
- js L(done)
- leal 8(%esi,%ecx,4), %esi C &src[size]
- xorl $-1, %ecx C -(size-1)
- L(top):
- C eax low prod
- C ebx low carry
- C ecx counter, negative
- C edx high prod
- C esi src end
- C edi dst end
- C ebp high carry (0 or -1)
- andl $1, %ebp C 1 or 0
- addl %eax, %ebx
- adcl %edx, %ebp
- ASSERT(nc)
- movl (%esi,%ecx,4), %eax
- mull VAR_MULT_LOW
- addl %eax, %ebx C low carry
- movl (%esi,%ecx,4), %eax
- adcl %ebp, %edx C high carry
- movl %ebx, (%edi,%ecx,4)
- sbbl %ebp, %ebp C new high carry, -1 or 0
- movl %edx, %ebx C new low carry
- mull VAR_MULT_HIGH
- incl %ecx
- jnz L(top)
- L(done):
- andl $1, %ebp C 1 or 0
- addl %ebx, %eax
- adcl %ebp, %edx
- ASSERT(nc)
- movl %eax, (%edi) C store carry low
- movl %edx, %eax C return carry high
- popl %ebp
- popl %ebx
- popl %edi
- popl %esi
- ret
- EPILOGUE()