pub fn decode(bytes: &[u8]) -> Option<(Inst, u8)>Expand description
Decode a single instruction starting at bytes[0].
Returns (inst, byte_length) where byte_length is 2 (compressed)
or 4 (standard). Returns None if fewer than 2 bytes are
available or the first 2 bytes are zero (which is Reserved
shape — we treat as decode failure to give the caller a clean
signal).