sub_byte
static uint8_t sub_byte (struct x86emu *, uint8_t d, uint8_t s);
sub_byte, /* 05 */
sub_byte, /* 05 */
common_binop_byte_rm_r(emu, sub_byte);
common_binop_byte_r_rm(emu, sub_byte);
common_binop_byte_imm(emu, sub_byte);