1 /* bitrotate.h - Rotate bits in integers
2 Copyright (C) 2008-2021 Free Software Foundation, Inc.
3
4 This file is free software: you can redistribute it and/or modify
5 it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 This file 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 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser 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. */
38 BITROTATE_INLINE uint64_t
39 rotl64 (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.*/
47 BITROTATE_INLINE uint64_t
48 rotr64 (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. */
57 BITROTATE_INLINE uint32_t
58 rotl32 (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.*/
66 BITROTATE_INLINE uint32_t
67 rotr32 (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. */
75 BITROTATE_INLINE size_t
76 rotl_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. */
84 BITROTATE_INLINE size_t
85 rotr_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. */
95 BITROTATE_INLINE uint16_t
96 rotl16 (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. */
107 BITROTATE_INLINE uint16_t
108 rotr16 (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. */
119 BITROTATE_INLINE uint8_t
120 rotl8 (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. */
130 BITROTATE_INLINE uint8_t
131 rotr8 (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 */