#[derive(Debug, Clone, Copy, PartialEq)]
pub enum Opcode {
    INVCHK = 0x20,
    TADD   = 0x30,
    TSUB   = 0x31,
    FADD   = 0x40,
    FVEL   = 0x41,
    CISS   = 0x50,
    CRET   = 0x51,
    CCAP   = 0x52,
    CDEF   = 0x54,
    CREW   = 0x55,
    IBND   = 0x60,
    IPRF   = 0x61,
    ILOCK  = 0x63,
    LBL    = 0x72,
    VCAST  = 0x80,
    VWEI   = 0x81,
    SIM    = 0x90,
    HALT   = 0xA0,
    NOOP   = 0xA1,
}

impl Opcode {
    pub fn from_byte(b: u8) -> Option<Self> {
        use Opcode::*;
        Some(match b {
            0x20 => INVCHK,
            0x30 => TADD,
            0x31 => TSUB,
            0x40 => FADD,
            0x41 => FVEL,
            0x50 => CISS,
            0x51 => CRET,
            0x52 => CCAP,
            0x54 => CDEF,
            0x55 => CREW,
            0x60 => IBND,
            0x61 => IPRF,
            0x63 => ILOCK,
            0x72 => LBL,
            0x80 => VCAST,
            0x81 => VWEI,
            0x90 => SIM,
            0xA0 => HALT,
            0xA1 => NOOP,
            _ => return None,
        })
    }
}