#[repr(u8)]
#[derive(Debug, Eq, PartialEq, Ord, PartialOrd, BitAnd)]
enum Register {
    RAX = 0, RCX = 1, RDX = 2,  RBX = 3,  RSP = 4,  RBP = 5,  RSI = 6,  RDI = 7,
    R8  = 8, R9  = 9, R10 = 10, R11 = 11, R12 = 12, R13 = 13, R14 = 14, R15 = 15,
}