A.5.16 BSWAP: Byte Swap
BSWAP reg32 ; o32 0F C8+r [486]
BSWAP swaps the order of the four bytes of a 32-bit register: bits 0-
7 exchange places with bits 24-31, and bits 8-15 swap with bits 16-23.
There is no explicit 16-bit equivalent: to byte-swap AX, BX, CX or DX,
XCHG can be used. When BSWAP is used with a 16-bit register, the result
is undefined.