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/* x86-64 __mpn_rshift --
Copyright (C) 2007-2024 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.
The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library; see the file COPYING.LIB. If not,
see <https://www.gnu.org/licenses/>. */
#include "sysdep.h"
#include "asm-syntax.h"
#define rp %rdi
#define up %rsi
#define n %rdx
#define cnt %cl
.text
ENTRY (__mpn_rshift)
mov %edx, %eax
and $3, %eax
jne L(nb00)
L(b00): /* n = 4, 8, 12, ... */
mov (up), %r10
mov 8(up), %r11
xor %eax, %eax
shrd %cl, %r10, %rax
mov 16(up), %r8
lea 8(up), up
lea -24(rp), rp
sub $4, n
jmp L(00)
L(nb00):/* n = 1, 5, 9, ... */
cmp $2, %eax
jae L(nb01)
L(b01): mov (up), %r9
xor %eax, %eax
shrd %cl, %r9, %rax
sub $2, n
jb L(le1)
mov 8(up), %r10
mov 16(up), %r11
lea 16(up), up
lea -16(rp), rp
jmp L(01)
L(le1): shr %cl, %r9
mov %r9, (rp)
ret
L(nb01):/* n = 2, 6, 10, ... */
jne L(b11)
L(b10): mov (up), %r8
mov 8(up), %r9
xor %eax, %eax
shrd %cl, %r8, %rax
sub $3, n
jb L(le2)
mov 16(up), %r10
lea 24(up), up
lea -8(rp), rp
jmp L(10)
L(le2): shrd %cl, %r9, %r8
mov %r8, (rp)
shr %cl, %r9
mov %r9, 8(rp)
ret
.p2align 4
L(b11): /* n = 3, 7, 11, ... */
mov (up), %r11
mov 8(up), %r8
xor %eax, %eax
shrd %cl, %r11, %rax
mov 16(up), %r9
lea 32(up), up
sub $4, n
jb L(end)
.p2align 4
L(top): shrd %cl, %r8, %r11
mov -8(up), %r10
mov %r11, (rp)
L(10): shrd %cl, %r9, %r8
mov (up), %r11
mov %r8, 8(rp)
L(01): shrd %cl, %r10, %r9
mov 8(up), %r8
mov %r9, 16(rp)
L(00): shrd %cl, %r11, %r10
mov 16(up), %r9
mov %r10, 24(rp)
add $32, up
lea 32(rp), rp
sub $4, n
jnc L(top)
L(end): shrd %cl, %r8, %r11
mov %r11, (rp)
shrd %cl, %r9, %r8
mov %r8, 8(rp)
shr %cl, %r9
mov %r9, 16(rp)
ret
END (__mpn_rshift)
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