A really simple CHIP8 emulator/interpreter written in Rust. Built using Tobias V. Langhoffs excellent guide: https://tobiasvl.github.io/blog/write-a-chip-8-emulator/
Uses Pixels and Winit for window and drawing to a texture.
Key handling is slightly inexact, uses key_held rather than keeping a local state of press/release.
- Sound playback
- Space invaders glitches after hitting a monster or two. Could be a COSMAC "quirk" that needs adressing.
- The interpreter (still) runs at a bit varying speed, especially when holding down keys.
I recently implemented a CHIP8 interpreter in Go (https://github.com/eriklupander/go-chip8) so I sort-of ported that code over to Rust as a learning excerise. Naturally, that means this is my very first Rust code ever and should be read as such!
I struggled a bit getting used to syntax, initializations, the borrow checker etc, but I think the end-result was rather nice, at least not a complete mess, which may say something about the Rust language.
While the Go implementation used Ebitengine's graphics and key-handling APIs, the winit / pixels combo used here was perhaps more straightforward once I got my head around its event-loop.
I chose to make the implementation multi-threaded with the interpreter running at approx 1000 ops/s, while the winit event-loop can tug along at whatever rate it likes. The interpreter thread uses a cloned ARC to write screen updates that the event-loop then could read using another ARC clone.
Using the Atomic reference counter and Mutex constructs turned out to be a really cool way to assert correctness. While I used sync.Mutex in the Go implementation, that was because I knew that I should do that - not because the compiler forced me to. (Though Go's race checker loudly complains!).
Also, using match (instruction, X, Y, N) including wildcards rather than nested switch statements was a really nice improvement compared to the Go version.
