lshift.asm
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上传日期：2022-08-06
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- dnl Intel P5 mpn_lshift -- mpn left shift.
- dnl Copyright 2000, 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: 1.75 cycles/limb.
- C mp_limb_t mpn_lshift (mp_ptr dst, mp_srcptr src, mp_size_t size,
- C unsigned shift);
- C
- C Shift src,size left by shift many bits and store the result in dst,size.
- C Zeros are shifted in at the right. Return the bits shifted out at the
- C left.
- C
- C The comments in mpn_rshift apply here too.
- defframe(PARAM_SHIFT,16)
- defframe(PARAM_SIZE, 12)
- defframe(PARAM_SRC, 8)
- defframe(PARAM_DST, 4)
- deflit(`FRAME',0)
- dnl minimum 5, because the unrolled loop can't handle less
- deflit(UNROLL_THRESHOLD, 5)
- TEXT
- ALIGN(8)
- PROLOGUE(mpn_lshift)
- pushl %ebx
- pushl %edi
- deflit(`FRAME',8)
- movl PARAM_SIZE, %eax
- movl PARAM_DST, %edx
- movl PARAM_SRC, %ebx
- movl PARAM_SHIFT, %ecx
- cmp $UNROLL_THRESHOLD, %eax
- jae L(unroll)
- movl -4(%ebx,%eax,4), %edi C src high limb
- decl %eax
- jnz L(simple)
- shldl( %cl, %edi, %eax) C eax was decremented to zero
- shll %cl, %edi
- movl %edi, (%edx) C dst low limb
- popl %edi C risk of data cache bank clash
- popl %ebx
- ret
- C -----------------------------------------------------------------------------
- L(simple):
- C eax size-1
- C ebx src
- C ecx shift
- C edx dst
- C esi
- C edi
- C ebp
- deflit(`FRAME',8)
- movd (%ebx,%eax,4), %mm5 C src high limb
- movd %ecx, %mm6 C lshift
- negl %ecx
- psllq %mm6, %mm5
- addl $32, %ecx
- movd %ecx, %mm7
- psrlq $32, %mm5 C retval
- L(simple_top):
- C eax counter, limbs, negative
- C ebx src
- C ecx
- C edx dst
- C esi
- C edi
- C
- C mm0 scratch
- C mm5 return value
- C mm6 shift
- C mm7 32-shift
- movq -4(%ebx,%eax,4), %mm0
- decl %eax
- psrlq %mm7, %mm0
- C
- movd %mm0, 4(%edx,%eax,4)
- jnz L(simple_top)
- movd (%ebx), %mm0
- movd %mm5, %eax
- psllq %mm6, %mm0
- popl %edi
- popl %ebx
- movd %mm0, (%edx)
- emms
- ret
- C -----------------------------------------------------------------------------
- ALIGN(8)
- L(unroll):
- C eax size
- C ebx src
- C ecx shift
- C edx dst
- C esi
- C edi
- C ebp
- deflit(`FRAME',8)
- movd -4(%ebx,%eax,4), %mm5 C src high limb
- leal (%ebx,%eax,4), %edi
- movd %ecx, %mm6 C lshift
- andl $4, %edi
- psllq %mm6, %mm5
- jz L(start_src_aligned)
- C src isn't aligned, process high limb separately (marked xxx) to
- C make it so.
- C
- C source -8(ebx,%eax,4)
- C |
- C +-------+-------+-------+--
- C | |
- C +-------+-------+-------+--
- C 0mod8 4mod8 0mod8
- C
- C dest
- C -4(edx,%eax,4)
- C |
- C +-------+-------+--
- C | xxx | |
- C +-------+-------+--
- movq -8(%ebx,%eax,4), %mm0 C unaligned load
- psllq %mm6, %mm0
- decl %eax
- psrlq $32, %mm0
- C
- movd %mm0, (%edx,%eax,4)
- L(start_src_aligned):
- movq -8(%ebx,%eax,4), %mm1 C src high qword
- leal (%edx,%eax,4), %edi
- andl $4, %edi
- psrlq $32, %mm5 C return value
- movq -16(%ebx,%eax,4), %mm3 C src second highest qword
- jz L(start_dst_aligned)
- C dst isn't aligned, subtract 4 to make it so, and pretend the shift
- C is 32 bits extra. High limb of dst (marked xxx) handled here
- C separately.
- C
- C source -8(ebx,%eax,4)
- C |
- C +-------+-------+--
- C | mm1 |
- C +-------+-------+--
- C 0mod8 4mod8
- C
- C dest
- C -4(edx,%eax,4)
- C |
- C +-------+-------+-------+--
- C | xxx | |
- C +-------+-------+-------+--
- C 0mod8 4mod8 0mod8
- movq %mm1, %mm0
- addl $32, %ecx C new shift
- psllq %mm6, %mm0
- movd %ecx, %mm6
- psrlq $32, %mm0
- C wasted cycle here waiting for %mm0
- movd %mm0, -4(%edx,%eax,4)
- subl $4, %edx
- L(start_dst_aligned):
- psllq %mm6, %mm1
- negl %ecx C -shift
- addl $64, %ecx C 64-shift
- movq %mm3, %mm2
- movd %ecx, %mm7
- subl $8, %eax C size-8
- psrlq %mm7, %mm3
- por %mm1, %mm3 C mm3 ready to store
- jc L(finish)
- C The comments in mpn_rshift apply here too.
- ALIGN(8)
- L(unroll_loop):
- C eax counter, limbs
- C ebx src
- C ecx
- C edx dst
- C esi
- C edi
- C
- C mm0
- C mm1
- C mm2 src qword from 16(%ebx,%eax,4)
- C mm3 dst qword ready to store to 24(%edx,%eax,4)
- C
- C mm5 return value
- C mm6 lshift
- C mm7 rshift
- movq 8(%ebx,%eax,4), %mm0
- psllq %mm6, %mm2
- movq %mm0, %mm1
- psrlq %mm7, %mm0
- movq %mm3, 24(%edx,%eax,4) C prev
- por %mm2, %mm0
- movq (%ebx,%eax,4), %mm3 C
- psllq %mm6, %mm1 C
- movq %mm0, 16(%edx,%eax,4)
- movq %mm3, %mm2 C
- psrlq %mm7, %mm3 C
- subl $4, %eax
- por %mm1, %mm3 C
- jnc L(unroll_loop)
- L(finish):
- C eax -4 to -1 representing respectively 0 to 3 limbs remaining
- testb $2, %al
- jz L(finish_no_two)
- movq 8(%ebx,%eax,4), %mm0
- psllq %mm6, %mm2
- movq %mm0, %mm1
- psrlq %mm7, %mm0
- movq %mm3, 24(%edx,%eax,4) C prev
- por %mm2, %mm0
- movq %mm1, %mm2
- movq %mm0, %mm3
- subl $2, %eax
- L(finish_no_two):
- C eax -4 or -3 representing respectively 0 or 1 limbs remaining
- C
- C mm2 src prev qword, from 16(%ebx,%eax,4)
- C mm3 dst qword, for 24(%edx,%eax,4)
- testb $1, %al
- movd %mm5, %eax C retval
- popl %edi
- jz L(finish_zero)
- C One extra src limb, destination was aligned.
- C
- C source ebx
- C --+---------------+-------+
- C | mm2 | |
- C --+---------------+-------+
- C
- C dest edx+12 edx+4 edx
- C --+---------------+---------------+-------+
- C | mm3 | | |
- C --+---------------+---------------+-------+
- C
- C mm6 = shift
- C mm7 = ecx = 64-shift
- C One extra src limb, destination was unaligned.
- C
- C source ebx
- C --+---------------+-------+
- C | mm2 | |
- C --+---------------+-------+
- C
- C dest edx+12 edx+4
- C --+---------------+---------------+
- C | mm3 | |
- C --+---------------+---------------+
- C
- C mm6 = shift+32
- C mm7 = ecx = 64-(shift+32)
- C In both cases there's one extra limb of src to fetch and combine
- C with mm2 to make a qword at 4(%edx), and in the aligned case
- C there's an extra limb of dst to be formed from that extra src limb
- C left shifted.
- movd (%ebx), %mm0
- psllq %mm6, %mm2
- movq %mm3, 12(%edx)
- psllq $32, %mm0
- movq %mm0, %mm1
- psrlq %mm7, %mm0
- por %mm2, %mm0
- psllq %mm6, %mm1
- movq %mm0, 4(%edx)
- psrlq $32, %mm1
- andl $32, %ecx
- popl %ebx
- jz L(finish_one_unaligned)
- movd %mm1, (%edx)
- L(finish_one_unaligned):
- emms
- ret
- L(finish_zero):
- C No extra src limbs, destination was aligned.
- C
- C source ebx
- C --+---------------+
- C | mm2 |
- C --+---------------+
- C
- C dest edx+8 edx
- C --+---------------+---------------+
- C | mm3 | |
- C --+---------------+---------------+
- C
- C mm6 = shift
- C mm7 = ecx = 64-shift
- C No extra src limbs, destination was unaligned.
- C
- C source ebx
- C --+---------------+
- C | mm2 |
- C --+---------------+
- C
- C dest edx+8 edx+4
- C --+---------------+-------+
- C | mm3 | |
- C --+---------------+-------+
- C
- C mm6 = shift+32
- C mm7 = ecx = 64-(shift+32)
- C The movd for the unaligned case writes the same data to 4(%edx)
- C that the movq does for the aligned case.
- movq %mm3, 8(%edx)
- andl $32, %ecx
- psllq %mm6, %mm2
- jz L(finish_zero_unaligned)
- movq %mm2, (%edx)
- L(finish_zero_unaligned):
- psrlq $32, %mm2
- popl %ebx
- movd %mm5, %eax C retval
- movd %mm2, 4(%edx)
- emms
- ret
- EPILOGUE()
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