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Goboy: Multi-Platform Nintendo Game Boy Color Emulator Written in Go
- jchw 8y agoCool! I also wrote a Gameboy emulator in Go, but I never got to supporting audio or GBC. I wonder how much harder it is to do Gameboy Color once you've got decent Gameboy DMG emulation?
- humpheh 8y agoThere aren't actually too many differences between GBC and DMG emulation as most of the hardware was consistent between them. The main change is around the PPU and the memory, as the GBC added some internal memory banks which are used for tile attributes and colour palettes etc. The actual changes around the graphics rendering aren't very significant other than some conditionals for GBC mode - you can see them here where `isGBC` is used: https://github.com/Humpheh/goboy/blob/master/pkg/gb/ppu.go https://github.com/Humpheh/goboy/blob/master/pkg/gb/ppu.go
- gf263 8y agoHow would someone begin to work on something like this?
- jchw 8y agoMy recommendation is to start with the CPU emulation. The CPU in the Gameboy has decent documentation and there are plenty of implementations to look at if you're stumped. (One I like particular is the core in Higan, a multisystem emulator written in C++.)
- voltagex_ 8y agoI remember seeing some people recommend starting with the NES rather than the Gameboy - any ideas on this?
- notafraudster 8y agoStart with Chip-8 or Space Invaders, both of which are substantially easier than the NES and Gameboy.
- 0xcde4c3db 8y agoThe main advantage to NES emulation is that it's a very mature area of study. High-quality documentation is much more readily available than for other systems, and there's more public discussion of the specific problems that NES emulator authors encounter (both primarily on nesdev.com [1] [2]). There's even a sort of tool-assisted speedrun of writing an accurate NES emulator, if you're into that sort of thing [3] [4]. [1] https://wiki.nesdev.com https://wiki.nesdev.com [2] https://forums.nesdev.com/viewforum.php?f=3 https://forums.nesdev.com/viewforum.php?f=3 [3] https://www.youtube.com/watch?v=y71lli8MS8s https://www.youtube.com/watch?v=y71lli8MS8s [4] https://www.youtube.com/watch?v=XZWw745wPXY https://www.youtube.com/watch?v=XZWw745wPXY
- hrydgard 8y agoGameboy is actually a bit friendlier than the NES to get started with, because of the low number of mappers (programmable chips in the cartridges to do tricks with addressing, NES had much greater need for these than the GB due to the dearth of tile RAM). But Sega Master System is even friendlier, I hear.
- corysama 8y agohttp://emulator101.com http://emulator101.com
- stevekemp 8y agohttp://emulator101.com/ http://emulator101.com/ is a good resource, as is https://www.reddit.com/r/emudev/ https://www.reddit.com/r/emudev/. Or you can just cheat, design a "toy" instruction set, and write something to process it. A couple of years ago I did that, in C/Perl: * https://github.com/skx/simple.vm https://github.com/skx/simple.vm Later I rewrote the interpreter/emulator in go: * https://github.com/skx/go.vm https://github.com/skx/go.vm The downside with my approach here is that I ignored graphcs, sound, & I/O. These days I'd recommend you write an emulator for the Chip-8 system..
- lostgame 8y agoI’ve often thought of writing my own emulator for the NES or GB/GBC to learn a little about how emulation works on a more fundamental level. I understand a lot of it is the process of translating machine code from, say, the GB processor to x86, but I’d love to learn more!
- akdas 8y ago> I understand a lot of it is the process of translating machine code from, say, the GB processor to x86, but I’d love to learn more! You don't really need to translate to x86 per se. You can start off with an interpreter that takes in the 6502 or Z80 instructions (as represented by the binary data in the input ROM), then immediately perform operations based on those instructions. For example, if you're holding onto an in-memory representation of the GB registers, and you encounter an "add" instruction, you would perform the addition and update the registers. And if you're writing the emulator in a high-level language, you never really think about x86 instructions. The hard part, then, is timing. You need to make sure the different operations that would be happening in hardware--namely performing the CPU instructions, alongside audio and video operations that would normally happen "in the background"--happen in sync. But that's a later step after you start on your first prototype!
- CobrastanJorji 8y agoI have a question there. CPU instructions and what they do are highly documented and easy to replicate, but I'm guessing that timing is significantly less slo. How do you get that right?
- akdas 8y agoTimings are usually documented as well, usually at the clock cycle level. Beyond that, you have to worry about hardware peculiarities that happen to affect maybe a few games, and at that point, you might start reverse engineering the behavior of those games! Take a look at this article talking about exactly those thinking issues: https://www.tested.com/tech/gaming/2712-why-perfect-hardware-snes-emulation-requires-a-3ghz-cpu/ https://www.tested.com/tech/gaming/2712-why-perfect-hardware...
- prevedmedved 8y ago> written in Go Who the hell cares?
- dang 8y agoMaybe no one, but please don't post unsubstantive comments to Hacker News.
- verletx64 8y agoAs somebody not versed at all in the front end part of an emulator, what’s a good resource for learning how to put together something that will actually render frames? No preference on technologies here.
- Double_a_92 8y agoEmulating the frame is also just part of the emulator. I.e. you got the display memory in some array (of pixel colors) in your code and the emulated instructions modify it. Then you just have to draw whatever is in that array on a "canvas" that your programming language supports.
- verletx64 8y agoIt’s the drawing bit that I don’t have much experience of haha
- staz 8y agocurrently following this https://cs108.epfl.ch/archive/18/p/00_introduction.html https://cs108.epfl.ch/archive/18/p/00_introduction.html but it is in French
- wareotie 8y agoI feel envy. I'm writing an NES emulator with a friend and it's taking so long... The gui is stealing my sanity. At least the CPU is completely done. I'll lurk his code :D
- subbz 8y agoWell done! Everybody who's interested in multiple platform emulation with a nice UI should check OpenEmu: https://openemu.org/ https://openemu.org/
- parski 8y agoI like that the language is a part of the name.
- minimaul 8y agoNice! As someone who also wrote a GB emulator as a learning exercise, I found the sound code to be the worst part by far to write - getting sound timing right etc is very difficult (as the GB sound output changes instantly - it has no buffers etc)
- giovannibajo1 8y agoFor something more complex, I have written a mostly working Nintendo DS emulator in Go, with JIT, 3D graphics, and whatnot: https://github.com/rasky/ndsemu/ https://github.com/rasky/ndsemu/
- igotsideas 8y agoLove the name!