mpir/mpn/x86_64/amd64/rshift1.asm

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dnl AMD64 mpn_rshift1
dnl Copyright 2008 Jason Moxham
dnl This file is part of the MPIR Library.
dnl The MPIR 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 2.1 of the License, or (at
dnl your option) any later version.
dnl The MPIR 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 MPIR Library; see the file COPYING.LIB. If not, write
dnl to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
dnl Boston, MA 02110-1301, USA.
include(`../config.m4')
C (rdi,rdx)=(rsi,rdx)>>1
C rax=carry
ASM_START()
PROLOGUE(mpn_rshift1)
xor %rax,%rax
lea -8(%rsi,%rdx,8),%rsi
lea -8(%rdi,%rdx,8),%rdi
mov %rdx,%r11
and $7,%r11
inc %r11
shr $3,%rdx
C and clear carry flag
cmp $0,%rdx
jz next
ALIGN(16)
loop:
mov (%rsi),%rcx
mov -8(%rsi),%r8
mov -16(%rsi),%r9
mov -24(%rsi),%r10
rcr $1,%rcx
rcr $1,%r8
rcr $1,%r9
rcr $1,%r10
mov %rcx,(%rdi)
mov %r8,-8(%rdi)
mov %r9,-16(%rdi)
mov %r10,-24(%rdi)
mov -32(%rsi),%rcx
mov -40(%rsi),%r8
mov -48(%rsi),%r9
mov -56(%rsi),%r10
rcr $1,%rcx
rcr $1,%r8
rcr $1,%r9
rcr $1,%r10
mov %rcx,-32(%rdi)
mov %r8,-40(%rdi)
mov %r9,-48(%rdi)
mov %r10,-56(%rdi)
lea -64(%rsi),%rsi
dec %rdx
lea -64(%rdi),%rdi
jnz loop
next:
dec %r11
jz end
C Could suffer cache-bank conflicts in this tail part
mov (%rsi),%rcx
rcr $1,%rcx
mov %rcx,(%rdi)
dec %r11
jz end
mov -8(%rsi),%rcx
rcr $1,%rcx
mov %rcx,-8(%rdi)
dec %r11
jz end
mov -16(%rsi),%rcx
rcr $1,%rcx
mov %rcx,-16(%rdi)
dec %r11
jz end
mov -24(%rsi),%rcx
rcr $1,%rcx
mov %rcx,-24(%rdi)
dec %r11
jz end
mov -32(%rsi),%rcx
rcr $1,%rcx
mov %rcx,-32(%rdi)
dec %r11
jz end
mov -40(%rsi),%rcx
rcr $1,%rcx
mov %rcx,-40(%rdi)
dec %r11
jz end
mov -48(%rsi),%rcx
rcr $1,%rcx
mov %rcx,-48(%rdi)
end:
rcr $1,%rax
ret
EPILOGUE()