| 1 | /* bitrotate.h - Rotate bits in integers
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| 2 | Copyright (C) 2008-2012 Free Software Foundation, Inc.
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| 3 |
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| 4 | This program is free software: you can redistribute it and/or modify
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| 5 | it under the terms of the GNU General Public License as published by
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| 6 | the Free Software Foundation; either version 3 of the License, or
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| 7 | (at your option) any later version.
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| 8 |
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| 9 | This program is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | GNU General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU General Public License
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| 15 | along with this program. If not, see <http://www.gnu.org/licenses/>. */
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| 16 |
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| 17 | /* Written by Simon Josefsson <simon@josefsson.org>, 2008. */
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| 18 |
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| 19 | #ifndef _GL_BITROTATE_H
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| 20 | #define _GL_BITROTATE_H
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| 21 |
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| 22 | #include <limits.h>
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| 23 | #include <stdint.h>
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| 24 | #include <sys/types.h>
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| 25 |
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| 26 | #ifdef UINT64_MAX
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| 27 | /* Given an unsigned 64-bit argument X, return the value corresponding
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| 28 | to rotating the bits N steps to the left. N must be between 1 and
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| 29 | 63 inclusive. */
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| 30 | static inline uint64_t
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| 31 | rotl64 (uint64_t x, int n)
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| 32 | {
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| 33 | return ((x << n) | (x >> (64 - n))) & UINT64_MAX;
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| 34 | }
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| 35 |
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| 36 | /* Given an unsigned 64-bit argument X, return the value corresponding
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| 37 | to rotating the bits N steps to the right. N must be between 1 to
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| 38 | 63 inclusive.*/
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| 39 | static inline uint64_t
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| 40 | rotr64 (uint64_t x, int n)
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| 41 | {
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| 42 | return ((x >> n) | (x << (64 - n))) & UINT64_MAX;
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| 43 | }
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| 44 | #endif
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| 45 |
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| 46 | /* Given an unsigned 32-bit argument X, return the value corresponding
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| 47 | to rotating the bits N steps to the left. N must be between 1 and
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| 48 | 31 inclusive. */
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| 49 | static inline uint32_t
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| 50 | rotl32 (uint32_t x, int n)
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| 51 | {
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| 52 | return ((x << n) | (x >> (32 - n))) & UINT32_MAX;
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| 53 | }
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| 54 |
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| 55 | /* Given an unsigned 32-bit argument X, return the value corresponding
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| 56 | to rotating the bits N steps to the right. N must be between 1 to
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| 57 | 31 inclusive.*/
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| 58 | static inline uint32_t
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| 59 | rotr32 (uint32_t x, int n)
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| 60 | {
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| 61 | return ((x >> n) | (x << (32 - n))) & UINT32_MAX;
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| 62 | }
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| 63 |
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| 64 | /* Given a size_t argument X, return the value corresponding
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| 65 | to rotating the bits N steps to the left. N must be between 1 and
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| 66 | (CHAR_BIT * sizeof (size_t) - 1) inclusive. */
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| 67 | static inline size_t
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| 68 | rotl_sz (size_t x, int n)
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| 69 | {
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| 70 | return ((x << n) | (x >> ((CHAR_BIT * sizeof x) - n))) & SIZE_MAX;
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| 71 | }
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| 72 |
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| 73 | /* Given a size_t argument X, return the value corresponding
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| 74 | to rotating the bits N steps to the right. N must be between 1 to
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| 75 | (CHAR_BIT * sizeof (size_t) - 1) inclusive. */
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| 76 | static inline size_t
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| 77 | rotr_sz (size_t x, int n)
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| 78 | {
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| 79 | return ((x >> n) | (x << ((CHAR_BIT * sizeof x) - n))) & SIZE_MAX;
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| 80 | }
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| 81 |
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| 82 | /* Given an unsigned 16-bit argument X, return the value corresponding
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| 83 | to rotating the bits N steps to the left. N must be between 1 to
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| 84 | 15 inclusive, but on most relevant targets N can also be 0 and 16
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| 85 | because 'int' is at least 32 bits and the arguments must widen
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| 86 | before shifting. */
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| 87 | static inline uint16_t
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| 88 | rotl16 (uint16_t x, int n)
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| 89 | {
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| 90 | return ((x << n) | (x >> (16 - n))) & UINT16_MAX;
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| 91 | }
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| 92 |
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| 93 | /* Given an unsigned 16-bit argument X, return the value corresponding
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| 94 | to rotating the bits N steps to the right. N must be in 1 to 15
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| 95 | inclusive, but on most relevant targets N can also be 0 and 16
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| 96 | because 'int' is at least 32 bits and the arguments must widen
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| 97 | before shifting. */
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| 98 | static inline uint16_t
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| 99 | rotr16 (uint16_t x, int n)
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| 100 | {
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| 101 | return ((x >> n) | (x << (16 - n))) & UINT16_MAX;
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| 102 | }
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| 103 |
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| 104 | /* Given an unsigned 8-bit argument X, return the value corresponding
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| 105 | to rotating the bits N steps to the left. N must be between 1 to 7
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| 106 | inclusive, but on most relevant targets N can also be 0 and 8
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| 107 | because 'int' is at least 32 bits and the arguments must widen
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| 108 | before shifting. */
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| 109 | static inline uint8_t
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| 110 | rotl8 (uint8_t x, int n)
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| 111 | {
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| 112 | return ((x << n) | (x >> (8 - n))) & UINT8_MAX;
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| 113 | }
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| 114 |
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| 115 | /* Given an unsigned 8-bit argument X, return the value corresponding
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| 116 | to rotating the bits N steps to the right. N must be in 1 to 7
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| 117 | inclusive, but on most relevant targets N can also be 0 and 8
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| 118 | because 'int' is at least 32 bits and the arguments must widen
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| 119 | before shifting. */
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| 120 | static inline uint8_t
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| 121 | rotr8 (uint8_t x, int n)
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| 122 | {
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| 123 | return ((x >> n) | (x << (8 - n))) & UINT8_MAX;
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| 124 | }
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| 125 |
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| 126 | #endif /* _GL_BITROTATE_H */
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