1/* bitrotate.h - Rotate bits in integers
2 Copyright (C) 2008-2019 Free Software Foundation, Inc.
3
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17/* Written by Simon Josefsson <simon@josefsson.org>, 2008. */
18
19#ifndef _GL_BITROTATE_H
20#define _GL_BITROTATE_H
21
22#include <limits.h>
23#include <stdint.h>
24#include <sys/types.h>
25
26#ifndef _GL_INLINE_HEADER_BEGIN
27 #error "Please include config.h first."
28#endif
29_GL_INLINE_HEADER_BEGIN
30#ifndef BITROTATE_INLINE
31# define BITROTATE_INLINE _GL_INLINE
32#endif
33
34#ifdef UINT64_MAX
35/* Given an unsigned 64-bit argument X, return the value corresponding
36 to rotating the bits N steps to the left. N must be between 1 and
37 63 inclusive. */
38BITROTATE_INLINE uint64_t
39rotl64 (uint64_t x, int n)
40{
41 return ((x << n) | (x >> (64 - n))) & UINT64_MAX;
42}
43
44/* Given an unsigned 64-bit argument X, return the value corresponding
45 to rotating the bits N steps to the right. N must be between 1 to
46 63 inclusive.*/
47BITROTATE_INLINE uint64_t
48rotr64 (uint64_t x, int n)
49{
50 return ((x >> n) | (x << (64 - n))) & UINT64_MAX;
51}
52#endif
53
54/* Given an unsigned 32-bit argument X, return the value corresponding
55 to rotating the bits N steps to the left. N must be between 1 and
56 31 inclusive. */
57BITROTATE_INLINE uint32_t
58rotl32 (uint32_t x, int n)
59{
60 return ((x << n) | (x >> (32 - n))) & UINT32_MAX;
61}
62
63/* Given an unsigned 32-bit argument X, return the value corresponding
64 to rotating the bits N steps to the right. N must be between 1 to
65 31 inclusive.*/
66BITROTATE_INLINE uint32_t
67rotr32 (uint32_t x, int n)
68{
69 return ((x >> n) | (x << (32 - n))) & UINT32_MAX;
70}
71
72/* Given a size_t argument X, return the value corresponding
73 to rotating the bits N steps to the left. N must be between 1 and
74 (CHAR_BIT * sizeof (size_t) - 1) inclusive. */
75BITROTATE_INLINE size_t
76rotl_sz (size_t x, int n)
77{
78 return ((x << n) | (x >> ((CHAR_BIT * sizeof x) - n))) & SIZE_MAX;
79}
80
81/* Given a size_t argument X, return the value corresponding
82 to rotating the bits N steps to the right. N must be between 1 to
83 (CHAR_BIT * sizeof (size_t) - 1) inclusive. */
84BITROTATE_INLINE size_t
85rotr_sz (size_t x, int n)
86{
87 return ((x >> n) | (x << ((CHAR_BIT * sizeof x) - n))) & SIZE_MAX;
88}
89
90/* Given an unsigned 16-bit argument X, return the value corresponding
91 to rotating the bits N steps to the left. N must be between 1 to
92 15 inclusive, but on most relevant targets N can also be 0 and 16
93 because 'int' is at least 32 bits and the arguments must widen
94 before shifting. */
95BITROTATE_INLINE uint16_t
96rotl16 (uint16_t x, int n)
97{
98 return (((unsigned int) x << n) | ((unsigned int) x >> (16 - n)))
99 & UINT16_MAX;
100}
101
102/* Given an unsigned 16-bit argument X, return the value corresponding
103 to rotating the bits N steps to the right. N must be in 1 to 15
104 inclusive, but on most relevant targets N can also be 0 and 16
105 because 'int' is at least 32 bits and the arguments must widen
106 before shifting. */
107BITROTATE_INLINE uint16_t
108rotr16 (uint16_t x, int n)
109{
110 return (((unsigned int) x >> n) | ((unsigned int) x << (16 - n)))
111 & UINT16_MAX;
112}
113
114/* Given an unsigned 8-bit argument X, return the value corresponding
115 to rotating the bits N steps to the left. N must be between 1 to 7
116 inclusive, but on most relevant targets N can also be 0 and 8
117 because 'int' is at least 32 bits and the arguments must widen
118 before shifting. */
119BITROTATE_INLINE uint8_t
120rotl8 (uint8_t x, int n)
121{
122 return (((unsigned int) x << n) | ((unsigned int) x >> (8 - n))) & UINT8_MAX;
123}
124
125/* Given an unsigned 8-bit argument X, return the value corresponding
126 to rotating the bits N steps to the right. N must be in 1 to 7
127 inclusive, but on most relevant targets N can also be 0 and 8
128 because 'int' is at least 32 bits and the arguments must widen
129 before shifting. */
130BITROTATE_INLINE uint8_t
131rotr8 (uint8_t x, int n)
132{
133 return (((unsigned int) x >> n) | ((unsigned int) x << (8 - n))) & UINT8_MAX;
134}
135
136_GL_INLINE_HEADER_END
137
138#endif /* _GL_BITROTATE_H */
139