bitrotate.h

/* bitrotate.h - Rotate bits in integers
 * Copyright (C) 2008-2012 Free Software Foundation, Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/* Written by Simon Josefsson <simon@josefsson.org>, 2008. */

#ifndef _GL_BITROTATE_H
#define _GL_BITROTATE_H

#include <limits.h>
#include <stdint.h>
#include <sys/types.h>

#ifndef STATIC_INLINE
# define STATIC_INLINE static inline
#endif /* STATIC_INLINE */

#ifdef UINT64_MAX
/* Given an unsigned 64-bit argument X, return the value corresponding
 * to rotating the bits N steps to the left.  N must be between 1 and
 * 63 inclusive. */
STATIC_INLINE uint64_t
rotl64(uint64_t x, int n)
{
  return (((x << n) | (x >> (64 - n))) & UINT64_MAX);
}

/* Given an unsigned 64-bit argument X, return the value corresponding
 * to rotating the bits N steps to the right.  N must be between 1 to
 * 63 inclusive.*/
STATIC_INLINE uint64_t
rotr64(uint64_t x, int n)
{
  return ((x >> n) | (x << (64 - n))) & UINT64_MAX;
}
#endif /* UINT64_MAX */

/* Given an unsigned 32-bit argument X, return the value corresponding
 * to rotating the bits N steps to the left.  N must be between 1 and
 * 31 inclusive. */
STATIC_INLINE uint32_t
rotl32(uint32_t x, int n)
{
  return (((x << n) | (x >> (32 - n))) & UINT32_MAX);
}

/* Given an unsigned 32-bit argument X, return the value corresponding
 * to rotating the bits N steps to the right.  N must be between 1 to
 * 31 inclusive.*/
STATIC_INLINE uint32_t
rotr32(uint32_t x, int n)
{
  return (((x >> n) | (x << (32 - n))) & UINT32_MAX);
}

/* Given a size_t argument X, return the value corresponding
 * to rotating the bits N steps to the left.  N must be between 1 and
 * (CHAR_BIT * sizeof (size_t) - 1) inclusive.  */
STATIC_INLINE size_t
rotl_sz(size_t x, int n)
{
  return (((x << n) | (x >> (((size_t)CHAR_BIT * sizeof(x)) - (unsigned long)n))) & SIZE_MAX);
}

/* Given a size_t argument X, return the value corresponding
 * to rotating the bits N steps to the right.  N must be between 1 to
 * (CHAR_BIT * sizeof (size_t) - 1) inclusive.  */
STATIC_INLINE size_t
rotr_sz(size_t x, int n)
{
  return (((x >> n) | (x << (((size_t)CHAR_BIT * sizeof(x)) - (unsigned long)n))) & SIZE_MAX);
}

/* Given an unsigned 16-bit argument X, return the value corresponding
 * to rotating the bits N steps to the left.  N must be between 1 to
 * 15 inclusive, but on most relevant targets N can also be 0 and 16
 * because 'int' is at least 32 bits and the arguments must widen
 * before shifting. */
STATIC_INLINE uint16_t
rotl16(uint16_t x, int n)
{
  return (uint16_t)(((x << n) | (x >> (16 - n))) & UINT16_MAX);
}

/* Given an unsigned 16-bit argument X, return the value corresponding
 * to rotating the bits N steps to the right.  N must be in 1 to 15
 * inclusive, but on most relevant targets N can also be 0 and 16
 * because 'int' is at least 32 bits and the arguments must widen
 * before shifting. */
STATIC_INLINE uint16_t
rotr16(uint16_t x, int n)
{
  return (uint16_t)(((x >> n) | (x << (16 - n))) & UINT16_MAX);
}

/* Given an unsigned 8-bit argument X, return the value corresponding
 * to rotating the bits N steps to the left.  N must be between 1 to 7
 * inclusive, but on most relevant targets N can also be 0 and 8
 * because 'int' is at least 32 bits and the arguments must widen
 * before shifting. */
STATIC_INLINE uint8_t
rotl8(uint8_t x, int n)
{
  return (uint8_t)(((x << n) | (x >> (8 - n))) & UINT8_MAX);
}

/* Given an unsigned 8-bit argument X, return the value corresponding
 * to rotating the bits N steps to the right.  N must be in 1 to 7
 * inclusive, but on most relevant targets N can also be 0 and 8
 * because 'int' is at least 32 bits and the arguments must widen
 * before shifting. */
STATIC_INLINE uint8_t
rotr8(uint8_t x, int n)
{
  return (uint8_t)(((x >> n) | (x << (8 - n))) & UINT8_MAX);
}

#endif /* _GL_BITROTATE_H */

/* EOF */