mul_1.asm
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上传日期:2022-08-06
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- dnl AMD K6 mpn_mul_1 -- mpn by limb multiply.
- dnl Copyright 1999, 2000, 2002, 2005 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
- C P5:
- C P6 model 0-8,10-12) 5.5
- C P6 model 9 (Banias)
- C P6 model 13 (Dothan) 4.87
- C P4 model 0 (Willamette)
- C P4 model 1 (?)
- C P4 model 2 (Northwood)
- C P4 model 3 (Prescott)
- C P4 model 4 (Nocona)
- C K6: 6.25
- C K7:
- C K8:
- C mp_limb_t mpn_mul_1 (mp_ptr dst, mp_srcptr src, mp_size_t size,
- C mp_limb_t multiplier);
- C mp_limb_t mpn_mul_1c (mp_ptr dst, mp_srcptr src, mp_size_t size,
- C mp_limb_t multiplier, mp_limb_t carry);
- C
- C Multiply src,size by mult and store the result in dst,size.
- C Return the carry limb from the top of the result.
- C
- C mpn_mul_1c() accepts an initial carry for the calculation, it's added into
- C the low limb of the result.
- defframe(PARAM_CARRY, 20)
- defframe(PARAM_MULTIPLIER,16)
- defframe(PARAM_SIZE, 12)
- defframe(PARAM_SRC, 8)
- defframe(PARAM_DST, 4)
- dnl minimum 5 because the unrolled code can't handle less
- deflit(UNROLL_THRESHOLD, 5)
- TEXT
- ALIGN(32)
- PROLOGUE(mpn_mul_1c)
- pushl %esi
- deflit(`FRAME',4)
- movl PARAM_CARRY, %esi
- jmp L(start_nc)
- EPILOGUE()
- PROLOGUE(mpn_mul_1)
- push %esi
- deflit(`FRAME',4)
- xorl %esi, %esi C initial carry
- L(start_nc):
- mov PARAM_SIZE, %ecx
- push %ebx
- FRAME_pushl()
- movl PARAM_SRC, %ebx
- push %edi
- FRAME_pushl()
- movl PARAM_DST, %edi
- pushl %ebp
- FRAME_pushl()
- cmpl $UNROLL_THRESHOLD, %ecx
- movl PARAM_MULTIPLIER, %ebp
- jae L(unroll)
- C code offset 0x22 here, close enough to aligned
- L(simple):
- C eax scratch
- C ebx src
- C ecx counter
- C edx scratch
- C esi carry
- C edi dst
- C ebp multiplier
- C
- C this loop 8 cycles/limb
- movl (%ebx), %eax
- addl $4, %ebx
- mull %ebp
- addl %esi, %eax
- movl $0, %esi
- adcl %edx, %esi
- movl %eax, (%edi)
- addl $4, %edi
- loop L(simple)
- popl %ebp
- popl %edi
- popl %ebx
- movl %esi, %eax
- popl %esi
- ret
- C -----------------------------------------------------------------------------
- C The code for each limb is 6 cycles, with instruction decoding being the
- C limiting factor. At 4 limbs/loop and 1 cycle/loop of overhead it's 6.25
- C cycles/limb in total.
- C
- C The secret ingredient to get 6.25 is to start the loop with the mul and
- C have the load/store pair at the end. Rotating the load/store to the top
- C is an 0.5 c/l slowdown. (Some address generation effect probably.)
- C
- C The whole unrolled loop fits nicely in exactly 80 bytes.
- ALIGN(16) C already aligned to 16 here actually
- L(unroll):
- movl (%ebx), %eax
- leal -16(%ebx,%ecx,4), %ebx
- leal -16(%edi,%ecx,4), %edi
- subl $4, %ecx
- negl %ecx
- ALIGN(16) C one byte nop for this alignment
- L(top):
- C eax scratch
- C ebx &src[size-4]
- C ecx counter
- C edx scratch
- C esi carry
- C edi &dst[size-4]
- C ebp multiplier
- mull %ebp
- addl %esi, %eax
- movl $0, %esi
- adcl %edx, %esi
- movl %eax, (%edi,%ecx,4)
- movl 4(%ebx,%ecx,4), %eax
- mull %ebp
- addl %esi, %eax
- movl $0, %esi
- adcl %edx, %esi
- movl %eax, 4(%edi,%ecx,4)
- movl 8(%ebx,%ecx,4), %eax
- mull %ebp
- addl %esi, %eax
- movl $0, %esi
- adcl %edx, %esi
- movl %eax, 8(%edi,%ecx,4)
- movl 12(%ebx,%ecx,4), %eax
- mull %ebp
- addl %esi, %eax
- movl $0, %esi
- adcl %edx, %esi
- movl %eax, 12(%edi,%ecx,4)
- movl 16(%ebx,%ecx,4), %eax
- addl $4, %ecx
- js L(top)
- C eax next src limb
- C ebx &src[size-4]
- C ecx 0 to 3 representing respectively 4 to 1 further limbs
- C edx
- C esi carry
- C edi &dst[size-4]
- testb $2, %cl
- jnz L(finish_not_two)
- mull %ebp
- addl %esi, %eax
- movl $0, %esi
- adcl %edx, %esi
- movl %eax, (%edi,%ecx,4)
- movl 4(%ebx,%ecx,4), %eax
- mull %ebp
- addl %esi, %eax
- movl $0, %esi
- adcl %edx, %esi
- movl %eax, 4(%edi,%ecx,4)
- movl 8(%ebx,%ecx,4), %eax
- addl $2, %ecx
- L(finish_not_two):
- testb $1, %cl
- jnz L(finish_not_one)
- mull %ebp
- addl %esi, %eax
- movl $0, %esi
- adcl %edx, %esi
- movl %eax, 8(%edi)
- movl 12(%ebx), %eax
- L(finish_not_one):
- mull %ebp
- addl %esi, %eax
- popl %ebp
- adcl $0, %edx
- movl %eax, 12(%edi)
- popl %edi
- popl %ebx
- movl %edx, %eax
- popl %esi
- ret
- EPILOGUE()