rshift.asm
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上传日期:2022-08-06
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- dnl PowerPC 750 mpn_rshift -- mpn right shift.
- dnl Copyright 2002, 2003 Free Software Foundation, Inc.
- dnl This file is part of the GNU MP Library.
- dnl The GNU MP Library is free software; you can redistribute it and/or modify
- dnl it under the terms of the GNU Lesser General Public License as published
- dnl by the Free Software Foundation; either version 3 of the License, or (at
- dnl your option) any later version.
- dnl The GNU MP Library is distributed in the hope that it will be useful, but
- dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
- dnl License for more details.
- 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 750: 3.0
- C 7400: 3.0
- C mp_limb_t mpn_rshift (mp_ptr dst, mp_srcptr src, mp_size_t size,
- C unsigned shift);
- C
- C This code is the same per-limb speed as mpn/powerpc32/rshift.asm, but
- C smaller and saving about 30 or so cycles of overhead.
- ASM_START()
- PROLOGUE(mpn_rshift)
- C r3 dst
- C r4 src
- C r5 size
- C r6 shift
- mtctr r5 C size
- lwz r8, 0(r4) C src[0]
- subfic r7, r6, 32 C 32-shift
- addi r5, r3, -4 C dst-4
- slw r3, r8, r7 C return value
- bdz L(one)
- lwzu r9, 4(r4) C src[1]
- srw r8, r8, r6 C src[0] >> shift
- bdz L(two)
- L(top):
- C r3 return value
- C r4 src, incrementing
- C r5 dst, incrementing
- C r6 shift
- C r7 32-shift
- C r8 src[i-1] >> shift
- C r9 src[i]
- C r10
- lwzu r10, 4(r4)
- slw r11, r9, r7
- or r8, r8, r11
- stwu r8, 4(r5)
- srw r8, r9, r6
- bdz L(odd)
- C r8 src[i-1] >> shift
- C r9
- C r10 src[i]
- lwzu r9, 4(r4)
- slw r11, r10, r7
- or r8, r8, r11
- stwu r8, 4(r5)
- srw r8, r10, r6
- bdnz L(top)
- L(two):
- C r3 return value
- C r4
- C r5 &dst[size-2]
- C r6 shift
- C r7 32-shift
- C r8 src[size-2] >> shift
- C r9 src[size-1]
- C r10
- slw r11, r9, r7
- srw r12, r9, r6 C src[size-1] >> shift
- or r8, r8, r11
- stw r12, 8(r5) C dst[size-1]
- stw r8, 4(r5) C dst[size-2]
- blr
- L(odd):
- C r3 return value
- C r4
- C r5 &dst[size-2]
- C r6 shift
- C r7 32-shift
- C r8 src[size-2] >> shift
- C r9
- C r10 src[size-1]
- slw r11, r10, r7
- srw r12, r10, r6
- or r8, r8, r11
- stw r12, 8(r5) C dst[size-1]
- stw r8, 4(r5) C dst[size-2]
- blr
- L(one):
- C r3 return value
- C r4
- C r5 dst-4
- C r6 shift
- C r7
- C r8 src[0]
- srw r8, r8, r6
- stw r8, 4(r5) C dst[0]
- blr
- EPILOGUE(mpn_rshift)