theornyx / dmg-go

A gameboy emulator written in Go (WIP)

DMG-go

DMG-go

Hi and welcome to the repo for my (still WIP) Gameboy DMG emulator written in go. This is a first attempt at systems stuff so it’s not the best and quite inaccurate but I hope this can serve as a good learning resource or smth for other people hoping to attempt the same thing.

NOTE - this was originally supposed to be a Gameboy Color emulator but I decided partway through to just focus on doing basic DMG emulation as CGB seemed to hard, however you may still find traces of GBC stuff in here

Screenshots

Keybinds

At the moment I don’t have custom keybinds done but it’s on my list, so these are the current keybinds

• Up - Up arrow key
• Down - Down arrow key
• Left - Left arrow key
• Right - Right arrow key
• A button - Z
• B button - X
• Start button - A
• Select button - S
• Switch between palettes - R (kinda finicky and needs a bit of fixing)

Current features and TODO’s

• [X] Functional (albeit inaccurate) CPU
• [X] Working PPU (but needs fixing)
• [X] Basic saving and loading
• [ ] Audio
• [ ] CGB support (probably unlikely)
• [ ] Custom keybinds
• [ ] Add more CLI flags
• [ ] Refactor code a bit
• [-] MBC support [4/5]
  • [X] MBC0
  • [X] MBC1
  • [ ] MBC2
  • [X] MBC3 (timer not implemented)
  • [X] MBC5

Resources and credits

I used a lot of resources and I also referenced some already existing gameboy/color emulators for inspiration and to get an idea of how they structured things and just kinda for help, below I will list some of these.

https://github.com/djhworld/gomeboycolor - this is another gameboy-color emulator written in go that I used as a reference point for a couple of parts of mine. It’s a very well made project and I thank the creator 🙏

https://gekkio.fi/files/gb-docs/gbctr.pdf - The gameboy technical reference. This one helped a lot with the creation of the CPU instruction functions as it helped me clearly see how some of the functions operated

https://gbdev.io/gb-opcodes//optables/ - This is one of quite a few tables that show all of the CPU instruction functions along with their OPCode and other stuff, this helped quite a lot with understanding the CPU instructions more as well

https://rylev.github.io/DMG-01/public/book/introduction.html - I didn’t end up following this one exactly but it was helpful as a baseline to help me understand the basics of emulating the system and served as a great entry point. Also really well written (even tho it uses rust 🤢)

https://gbdev.io/pandocs - The absolute beast, like 90% of the information I gained came from this, many places tell you to use this and I can see why. It’s amazingly written and while it can be a little bit confusing it’s amazing reference material

https://hacktix.github.io/GBEDG/ - Great for helping with quite a few things as it specified some things that are either vaguely described in the pandocs or just aren’t