lib/bitrotate.h

   1 /* bitrotate.h - Rotate bits in integers
   2    Copyright (C) 2008-2024 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 /* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE.  */
  23 #if !_GL_CONFIG_H_INCLUDED
  24  #error "Please include config.h first."
  25 #endif
  26
  27 #include <limits.h>
  28 #include <stdint.h>
  29 #include <sys/types.h>
  30
  31 _GL_INLINE_HEADER_BEGIN
  32 #ifndef BITROTATE_INLINE
  33 # define BITROTATE_INLINE _GL_INLINE
  34 #endif
  35
  36 #ifdef UINT64_MAX
  37 /* Given an unsigned 64-bit argument X, return the value corresponding
  38    to rotating the bits N steps to the left.  N must be between 1 and
  39    63 inclusive. */
  40 BITROTATE_INLINE uint64_t
  41 rotl64 (uint64_t x, int n)
  42 {
  43   return ((x << n) | (x >> (64 - n))) & UINT64_MAX;
  44 }
  45
  46 /* Given an unsigned 64-bit argument X, return the value corresponding
  47    to rotating the bits N steps to the right.  N must be between 1 to
  48    63 inclusive.*/
  49 BITROTATE_INLINE uint64_t
  50 rotr64 (uint64_t x, int n)
  51 {
  52   return ((x >> n) | (x << (64 - n))) & UINT64_MAX;
  53 }
  54 #endif
  55
  56 /* Given an unsigned 32-bit argument X, return the value corresponding
  57    to rotating the bits N steps to the left.  N must be between 1 and
  58    31 inclusive. */
  59 BITROTATE_INLINE uint32_t
  60 rotl32 (uint32_t x, int n)
  61 {
  62   return ((x << n) | (x >> (32 - n))) & UINT32_MAX;
  63 }
  64
  65 /* Given an unsigned 32-bit argument X, return the value corresponding
  66    to rotating the bits N steps to the right.  N must be between 1 to
  67    31 inclusive.*/
  68 BITROTATE_INLINE uint32_t
  69 rotr32 (uint32_t x, int n)
  70 {
  71   return ((x >> n) | (x << (32 - n))) & UINT32_MAX;
  72 }
  73
  74 /* Given a size_t argument X, return the value corresponding
  75    to rotating the bits N steps to the left.  N must be between 1 and
  76    (CHAR_BIT * sizeof (size_t) - 1) inclusive.  */
  77 BITROTATE_INLINE size_t
  78 rotl_sz (size_t x, int n)
  79 {
  80   return ((x << n) | (x >> ((CHAR_BIT * sizeof x) - n))) & SIZE_MAX;
  81 }
  82
  83 /* Given a size_t argument X, return the value corresponding
  84    to rotating the bits N steps to the right.  N must be between 1 to
  85    (CHAR_BIT * sizeof (size_t) - 1) inclusive.  */
  86 BITROTATE_INLINE size_t
  87 rotr_sz (size_t x, int n)
  88 {
  89   return ((x >> n) | (x << ((CHAR_BIT * sizeof x) - n))) & SIZE_MAX;
  90 }
  91
  92 /* Given an unsigned 16-bit argument X, return the value corresponding
  93    to rotating the bits N steps to the left.  N must be between 1 to
  94    15 inclusive, but on most relevant targets N can also be 0 and 16
  95    because 'int' is at least 32 bits and the arguments must widen
  96    before shifting. */
  97 BITROTATE_INLINE uint16_t
  98 rotl16 (uint16_t x, int n)
  99 {
 100   return (((unsigned int) x << n) | ((unsigned int) x >> (16 - n)))
 101          & UINT16_MAX;
 102 }
 103
 104 /* Given an unsigned 16-bit argument X, return the value corresponding
 105    to rotating the bits N steps to the right.  N must be in 1 to 15
 106    inclusive, but on most relevant targets N can also be 0 and 16
 107    because 'int' is at least 32 bits and the arguments must widen
 108    before shifting. */
 109 BITROTATE_INLINE uint16_t
 110 rotr16 (uint16_t x, int n)
 111 {
 112   return (((unsigned int) x >> n) | ((unsigned int) x << (16 - n)))
 113          & UINT16_MAX;
 114 }
 115
 116 /* Given an unsigned 8-bit argument X, return the value corresponding
 117    to rotating the bits N steps to the left.  N must be between 1 to 7
 118    inclusive, but on most relevant targets N can also be 0 and 8
 119    because 'int' is at least 32 bits and the arguments must widen
 120    before shifting. */
 121 BITROTATE_INLINE uint8_t
 122 rotl8 (uint8_t x, int n)
 123 {
 124   return (((unsigned int) x << n) | ((unsigned int) x >> (8 - n))) & UINT8_MAX;
 125 }
 126
 127 /* Given an unsigned 8-bit argument X, return the value corresponding
 128    to rotating the bits N steps to the right.  N must be in 1 to 7
 129    inclusive, but on most relevant targets N can also be 0 and 8
 130    because 'int' is at least 32 bits and the arguments must widen
 131    before shifting. */
 132 BITROTATE_INLINE uint8_t
 133 rotr8 (uint8_t x, int n)
 134 {
 135   return (((unsigned int) x >> n) | ((unsigned int) x << (8 - n))) & UINT8_MAX;
 136 }
 137
 138 _GL_INLINE_HEADER_END
 139
 140 #endif /* _GL_BITROTATE_H */