Byte-Swapping Builtins (Using the GNU Compiler Collection (GCC))

7.2.3 Byte-Swapping Builtins

Built-in Function: uint16_t __builtin_bswap16 (uint16_t x): Returns x with the order of the bytes reversed; for example, 0xabcd becomes 0xcdab. Byte here always means exactly 8 bits.

Built-in Function: uint32_t __builtin_bswap32 (uint32_t x): Similar to __builtin_bswap16, except the argument and return types are 32-bit.

Built-in Function: uint64_t __builtin_bswap64 (uint64_t x): Similar to __builtin_bswap32, except the argument and return types are 64-bit.

Built-in Function: uint128_t __builtin_bswap128 (uint128_t x): Similar to __builtin_bswap64, except the argument and return types are 128-bit. Only supported on targets when 128-bit types are supported.