lib/bitrotate.h

   1 /* bitrotate.h - Rotate bits in integers
   2    Copyright (C) 2008-2021 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. */
  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 */