endianswap.h

/** @file Macros for performing byte swapping for quick endian conversion.

    It will try to use the fast built-in machine instructions first
    and fall back to the slow conversion if none were found.
 */

#ifndef ENDIAN_SWAP_H
#define ENDIAN_SWAP_H

#ifdef __GNUG__ /* GCC, ICC and Clang */

#   ifdef __APPLE__
#       include <machine/endian.h>
#   else
#       include <endian.h>
#   endif

#   define BYTESWAP_16(x) (__builtin_bswap16 (x))
#   define BYTESWAP_32(x) (__builtin_bswap32 (x))
#   define BYTESWAP_64(x) (__builtin_bswap64 (x))

#elif _MSC_VER   /* MSVC */

#   include <stdlib.h>

#   define BYTESWAP_16(x) (_byteswap_ushort (x))
#   define BYTESWAP_32(x) (_byteswap_ulong (x))
#   define BYTESWAP_64(x) (_byteswap_uint64 (x))

#else

#   warning "Unknown byte swapping built-ins (do it the slow way)!"

#   define BYTESWAP_16(x) ((x) >> 8)  | (((x) & 0xFFUL) << 8)

#   define BYTESWAP_32(x) ((x) >> 24) | (((x) >> 8) & 0xFF00UL) | \
                         (((x) & 0xFF00UL) << 8) | ((x) << 24)

#   define BYTESWAP_64(x)                       \
         ((x) >> 56)                          | \
        (((x) & 0x00FF000000000000ULL) >> 48) | \
        (((x) & 0x0000FF0000000000ULL) >> 40) | \
        (((x) & 0x000000FF00000000ULL) >> 32) | \
        (((x) & 0x00000000FF000000ULL) << 32) | \
        (((x) & 0x0000000000FF0000ULL) << 40) | \
        (((x) & 0x000000000000FF00ULL) << 48) | \
        (((x) & 0x00000000000000FFULL) << 56)

#endif

#endif /* ENDIAN_SWAP_H */