1/* x86-64 __mpn_rshift --
2 Copyright (C) 2007-2021 Free Software Foundation, Inc.
3 This file is part of the GNU MP Library.
4
5 The GNU MP Library is free software; you can redistribute it and/or modify
6 it under the terms of the GNU Lesser General Public License as published by
7 the Free Software Foundation; either version 2.1 of the License, or (at your
8 option) any later version.
9
10 The GNU MP Library is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
12 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
13 License for more details.
14
15 You should have received a copy of the GNU Lesser General Public License
16 along with the GNU MP Library; see the file COPYING.LIB. If not,
17 see <https://www.gnu.org/licenses/>. */
18
19#include "sysdep.h"
20#include "asm-syntax.h"
21
22#define rp %rdi
23#define up %rsi
24#define n %rdx
25#define cnt %cl
26
27 .text
28ENTRY (__mpn_rshift)
29 mov %edx, %eax
30 and $3, %eax
31 jne L(nb00)
32L(b00): /* n = 4, 8, 12, ... */
33 mov (up), %r10
34 mov 8(up), %r11
35 xor %eax, %eax
36 shrd %cl, %r10, %rax
37 mov 16(up), %r8
38 lea 8(up), up
39 lea -24(rp), rp
40 sub $4, n
41 jmp L(00)
42
43L(nb00):/* n = 1, 5, 9, ... */
44 cmp $2, %eax
45 jae L(nb01)
46L(b01): mov (up), %r9
47 xor %eax, %eax
48 shrd %cl, %r9, %rax
49 sub $2, n
50 jb L(le1)
51 mov 8(up), %r10
52 mov 16(up), %r11
53 lea 16(up), up
54 lea -16(rp), rp
55 jmp L(01)
56L(le1): shr %cl, %r9
57 mov %r9, (rp)
58 ret
59
60L(nb01):/* n = 2, 6, 10, ... */
61 jne L(b11)
62L(b10): mov (up), %r8
63 mov 8(up), %r9
64 xor %eax, %eax
65 shrd %cl, %r8, %rax
66 sub $3, n
67 jb L(le2)
68 mov 16(up), %r10
69 lea 24(up), up
70 lea -8(rp), rp
71 jmp L(10)
72L(le2): shrd %cl, %r9, %r8
73 mov %r8, (rp)
74 shr %cl, %r9
75 mov %r9, 8(rp)
76 ret
77
78 .p2align 4
79L(b11): /* n = 3, 7, 11, ... */
80 mov (up), %r11
81 mov 8(up), %r8
82 xor %eax, %eax
83 shrd %cl, %r11, %rax
84 mov 16(up), %r9
85 lea 32(up), up
86 sub $4, n
87 jb L(end)
88
89 .p2align 4
90L(top): shrd %cl, %r8, %r11
91 mov -8(up), %r10
92 mov %r11, (rp)
93L(10): shrd %cl, %r9, %r8
94 mov (up), %r11
95 mov %r8, 8(rp)
96L(01): shrd %cl, %r10, %r9
97 mov 8(up), %r8
98 mov %r9, 16(rp)
99L(00): shrd %cl, %r11, %r10
100 mov 16(up), %r9
101 mov %r10, 24(rp)
102 add $32, up
103 lea 32(rp), rp
104 sub $4, n
105 jnc L(top)
106
107L(end): shrd %cl, %r8, %r11
108 mov %r11, (rp)
109 shrd %cl, %r9, %r8
110 mov %r8, 8(rp)
111 shr %cl, %r9
112 mov %r9, 16(rp)
113 ret
114END (__mpn_rshift)
115