Generate Game Boy CPU Opcodes

This is a side project that came out of my attempt to make a Game Boy emulator. I was trying to make a table of opcodes for the Game Boy CPU (similar to the one on pastraiser), but doing it by hand was quite tedious. So this project dynamically creates a similar table!

Code Key

• r - 8-bit register (e.g. A)
• rr - 16-bit register pair (e.g. HL)
• d8 - 8-bit immediate data value
• d16 - 16-bit immediate data value
• a8 - 8-bit immediate value specifying an address in the range 0xFF00 - 0xFFFF
• a16 - 16-bit immediate address value
• s8 - 8-bit signed immediate data value

Note: Some conditional jump instructions take a different number of cycles depending on whether or not the specified condition is true (e.g., JP NZ, a16).

Additional Resources

• Gist: Game Boy carry and half-carry flags
• Twitter thread of resources for building a Game Boy emulator

Credits

Game Boy Resources

• Gameboy Development Manual v1.1 - I used this to create the generator functions for the different permutations of each mnemonic.
• Gameboy CPU (LR35902) instruction set - This is the original site that inspired this project.

Things That Helped Me Build This Project

• How to create an Opt-Out link for Google Analytics