src/include/swab.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 /*
   4  * linux/byteorder/swab.h
   5  * Byte-swapping, independently from CPU endianness
   6  *      swabXX[ps]?(foo)
   7  *
   8  * Francois-Rene Rideau <fare@tunes.org> 19971205
   9  *    separated swab functions from cpu_to_XX,
  10  *    to clean up support for bizarre-endian architectures.
  11  *
  12  * See asm-i386/byteorder.h and such for examples of how to provide
  13  * architecture-dependent optimized versions
  14  *
  15  */
  16
  17 /* casts are necessary for constants, because we never know how for sure
  18  * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
  19  */
  20
  21 #ifndef _SWAB_H
  22 #define _SWAB_H
  23
  24 #include <stdint.h>
  25
  26 #if ENV_ARMV4
  27 #define swab16(x) \
  28         ((unsigned short)( \
  29                 (((unsigned short)(x) & (unsigned short)0x00ffU) << 8) | \
  30                 (((unsigned short)(x) & (unsigned short)0xff00U) >> 8)))
  31
  32 #define swab32(x) \
  33         ((unsigned int)( \
  34                 (((unsigned int)(x) & 0x000000ffUL) << 24) | \
  35                 (((unsigned int)(x) & 0x0000ff00UL) <<  8) | \
  36                 (((unsigned int)(x) & 0x00ff0000UL) >>  8) | \
  37                 (((unsigned int)(x) & 0xff000000UL) >> 24)))
  38
  39 #define swab64(x) \
  40         ((uint64_t)( \
  41                 (((uint64_t)(x) & (uint64_t)0x00000000000000ffULL) << 56) | \
  42                 (((uint64_t)(x) & (uint64_t)0x000000000000ff00ULL) << 40) | \
  43                 (((uint64_t)(x) & (uint64_t)0x0000000000ff0000ULL) << 24) | \
  44                 (((uint64_t)(x) & (uint64_t)0x00000000ff000000ULL) <<  8) | \
  45                 (((uint64_t)(x) & (uint64_t)0x000000ff00000000ULL) >>  8) | \
  46                 (((uint64_t)(x) & (uint64_t)0x0000ff0000000000ULL) >> 24) | \
  47                 (((uint64_t)(x) & (uint64_t)0x00ff000000000000ULL) >> 40) | \
  48                 (((uint64_t)(x) & (uint64_t)0xff00000000000000ULL) >> 56)))
  49 #else   /* ENV_ARMV4 */
  50 #define swab16(x) ((uint16_t)__builtin_bswap16(x))
  51 #define swab32(x) ((uint32_t)__builtin_bswap32(x))
  52 #define swab64(x) ((uint64_t)__builtin_bswap64(x))
  53 #endif  /* !ENV_ARMV4 */
  54
  55 #endif /* _SWAB_H */