| Opcode | Instruction | Op/En | 64-bit Mode | Compat/Leg Mode | Description | | ------------------ | ----------- | ----- | ----------- | --------------- | --------------------------------------------- | | 0F C8+_rd_ | BSWAP _r32_ | O | Valid | Valid | Reverses the byte order of a 32-bit register. | | REX.W + 0F C8+_rd_ | BSWAP _r64_ | O | Valid | N.E. | Reverses the byte order of a 64-bit register. |