Show HN: IronBoy, a highly accurate GameBoy emulator written in Rust, runs WASM

[nicolas-siplis]

Hey HN! Been working on this emulator on and off for the last couple years, and thought now would be a good time to try and show it off here.

As far as unique features... I think this is the only online GameBoy emulator with support for save files? So there's your reason to exist, I guess.

The WASM port was something I had in the back of my mind but I just kept putting it off because it seemed like it would've been a pain in the ass to implement, but all in all I think it took less than a week so that was a nice surprise!

[sphars]

Tried it out with a couple of ROMs. Seemed to work fine with Pokemon Red, but Tetris failed with stutters, garbled audio, and no inputs (maybe it's my ROM? works fine on other emulators). Also, clicking on on the buttons didn't work in either case but keyboard controls work.

Super interesting to see it working in a browser though! Nice work.

[zackangelo]

"runs WASM" made me wonder: is transpiling a ROM to WASM an effective strategy for emulating something like a GameBoy? You'd still have many issues to solve, not least of which mapping the hardware onto a runtime layer, but you'd benefit from all of the innovation happening in the WASM ecosystem.

[pornel]

It could give you JIT for free, but I don't think it's a silver bullet.

It would be hard to implement. ROM is unstructured data, interpreted however the game wants. You'd need some heuristics or instrumentation to find which parts are code, and where the code jumps to.

You still need the hardware emulated, and emulation ideally should be cycle accurate, so the generated WASM would be tightly coupled to the emulator. Resulting binary likely would be larger, as I expect 8-bit Thumb code to be more compact than 32-bit WASM.

[circuit10]

Sort of related: https://andrewkelley.me/post/jamulator.html

[arco1991]

Awesome! Nice work.