[userbinator]

The Gameboy CPU shares the same octal-structured opcode format as the Z80 from which it was derived, so it is possible to decode it even more concisely: http://www.z80.info/decoding.htm

You can see that in octal, 1xx are all moves while 2xx is all ALU ops.

[deaddodo]

Oh, it's definitely decodable. Most CPU's can be (though x86 post-386 wouldn't be fun), since that's what they're usually doing internally. But, with 8-bit CPU's, the opcode space is usually limited to a byte, which makes tables very doable and very efficient.

My rust-based GB emulator uses a decoder based on those very docs, in fact. Though, modified slightly since the GB's CPU only supports the CB-extended range operations.