1/* bitrotate.h - Rotate bits in integers
2   Copyright (C) 2008-2012 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 <http://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_GL_INLINE_HEADER_BEGIN
27#ifndef BITROTATE_INLINE
28# define BITROTATE_INLINE _GL_INLINE
29#endif
30
31#ifdef UINT64_MAX
32/* Given an unsigned 64-bit argument X, return the value corresponding
33   to rotating the bits N steps to the left.  N must be between 1 and
34   63 inclusive. */
35BITROTATE_INLINE uint64_t
36rotl64 (uint64_t x, int n)
37{
38  return ((x << n) | (x >> (64 - n))) & UINT64_MAX;
39}
40
41/* Given an unsigned 64-bit argument X, return the value corresponding
42   to rotating the bits N steps to the right.  N must be between 1 to
43   63 inclusive.*/
44BITROTATE_INLINE uint64_t
45rotr64 (uint64_t x, int n)
46{
47  return ((x >> n) | (x << (64 - n))) & UINT64_MAX;
48}
49#endif
50
51/* Given an unsigned 32-bit argument X, return the value corresponding
52   to rotating the bits N steps to the left.  N must be between 1 and
53   31 inclusive. */
54BITROTATE_INLINE uint32_t
55rotl32 (uint32_t x, int n)
56{
57  return ((x << n) | (x >> (32 - n))) & UINT32_MAX;
58}
59
60/* Given an unsigned 32-bit argument X, return the value corresponding
61   to rotating the bits N steps to the right.  N must be between 1 to
62   31 inclusive.*/
63BITROTATE_INLINE uint32_t
64rotr32 (uint32_t x, int n)
65{
66  return ((x >> n) | (x << (32 - n))) & UINT32_MAX;
67}
68
69/* Given a size_t argument X, return the value corresponding
70   to rotating the bits N steps to the left.  N must be between 1 and
71   (CHAR_BIT * sizeof (size_t) - 1) inclusive.  */
72BITROTATE_INLINE size_t
73rotl_sz (size_t x, int n)
74{
75  return ((x << n) | (x >> ((CHAR_BIT * sizeof x) - n))) & SIZE_MAX;
76}
77
78/* Given a size_t argument X, return the value corresponding
79   to rotating the bits N steps to the right.  N must be between 1 to
80   (CHAR_BIT * sizeof (size_t) - 1) inclusive.  */
81BITROTATE_INLINE size_t
82rotr_sz (size_t x, int n)
83{
84  return ((x >> n) | (x << ((CHAR_BIT * sizeof x) - n))) & SIZE_MAX;
85}
86
87/* Given an unsigned 16-bit argument X, return the value corresponding
88   to rotating the bits N steps to the left.  N must be between 1 to
89   15 inclusive, but on most relevant targets N can also be 0 and 16
90   because 'int' is at least 32 bits and the arguments must widen
91   before shifting. */
92BITROTATE_INLINE uint16_t
93rotl16 (uint16_t x, int n)
94{
95  return ((x << n) | (x >> (16 - n))) & UINT16_MAX;
96}
97
98/* Given an unsigned 16-bit argument X, return the value corresponding
99   to rotating the bits N steps to the right.  N must be in 1 to 15
100   inclusive, but on most relevant targets N can also be 0 and 16
101   because 'int' is at least 32 bits and the arguments must widen
102   before shifting. */
103BITROTATE_INLINE uint16_t
104rotr16 (uint16_t x, int n)
105{
106  return ((x >> n) | (x << (16 - n))) & UINT16_MAX;
107}
108
109/* Given an unsigned 8-bit argument X, return the value corresponding
110   to rotating the bits N steps to the left.  N must be between 1 to 7
111   inclusive, but on most relevant targets N can also be 0 and 8
112   because 'int' is at least 32 bits and the arguments must widen
113   before shifting. */
114BITROTATE_INLINE uint8_t
115rotl8 (uint8_t x, int n)
116{
117  return ((x << n) | (x >> (8 - n))) & UINT8_MAX;
118}
119
120/* Given an unsigned 8-bit argument X, return the value corresponding
121   to rotating the bits N steps to the right.  N must be in 1 to 7
122   inclusive, but on most relevant targets N can also be 0 and 8
123   because 'int' is at least 32 bits and the arguments must widen
124   before shifting. */
125BITROTATE_INLINE uint8_t
126rotr8 (uint8_t x, int n)
127{
128  return ((x >> n) | (x << (8 - n))) & UINT8_MAX;
129}
130
131_GL_INLINE_HEADER_END
132
133#endif /* _GL_BITROTATE_H */
134