OpcodeByte

const OpcodeByte = packed struct(u8) {
    low: packed union {
        operand: u6,
        extended: enum(u6) {
            nop = 0,
            set_loc = 1,
            advance_loc1 = 2,
            advance_loc2 = 3,
            advance_loc4 = 4,
            offset_extended = 5,
            restore_extended = 6,
            undefined = 7,
            same_value = 8,
            register = 9,
            remember_state = 10,
            restore_state = 11,
            def_cfa = 12,
            def_cfa_register = 13,
            def_cfa_offset = 14,
            def_cfa_expression = 15,
            expression = 16,
            offset_extended_sf = 17,
            def_cfa_sf = 18,
            def_cfa_offset_sf = 19,
            val_offset = 20,
            val_offset_sf = 21,
            val_expression = 22,
            _,
        },
    },
    opcode: enum(u2) {
        extended = 0,
        advance_loc = 1,
        offset = 2,
        restore = 3,
    },
}