Making SNES ROMs using C#(reddit.com) |
Making SNES ROMs using C#(reddit.com) |
EDIT: I overlooked the reddit post and comments and jumped straight into the repo, it looks like the creator is on an insane quest to get C# to run anywhere haha, I didn't realize the C tanspiler was by the same author.
So the code in the game example is very much a "port directly from the example C code to make sure it's possible and it works". The next step was to start looking at where things can be made more idiomatic.
For example, C# supports static methods in interfaces now. This means instead of passing function pointers around for things you can create a class that implements an interface and call `InitObjects<T>()` instead of `InitObjects(&initFunction, &updateFunction, null)`, and I think I can do that in a no overhead way.
There are some other ideas I have for making things more idiomatic, but I really wanted to make sure I had a working ROM first before I started mangling the examples and trying to figure out if it's my transpiler or my logic that's breaking things.
There is a limit to how idiomatic I can make it though. Since the SNES has limited memory, any stack variable you create risks accidentally overwriting other memory. So it seems like you want to limit how many stack variables you use, which ends up meaning storing things in pointers and globals when using them.
There are some other slight advantages, like better enums, but yeah. At the end of the day this is a usecase of my transpiler allowing C# to be used on non-standard platforms.
If 'T' is a struct, yup, although that's specific to the way it is compiled by CoreCLR's JIT or ILC.
For constructor semantics it's best to expose a static abstract interface method Create<T> and have the interface be SomeInterface<Self> where Self : ISomeInterface<Self>.
For example, that's how `INumber<T>` interface works so you can further down the line write `T.Zero`.
C# could be much nicer to write than C. "Low-level" C# is still idiomatic, even if you use memory-safe constructs i.e. Span<T> and friends.
There is nothing wrong with writing C# that has structs, ref Ts and not a single class.
At work, I have ported a certain C dependency to C# to fix long-standing bugs, get rid of C build systems and portability problems and gain 2-10x performance improvement (by fixing suboptimal data structure use and switching to text scanning with SearchValues<char> which is heavily vectorized).
The end result is still idiomatic and arguably easier to read. But yes, it looks very different to the average enterprise codebase.
When I started this journey I had a hard time figuring out how open source il2cpp actually was, and it seemed to be heavily tied to unity. All the docs seemed heavily geared towards unity usage as well.
Likewise, some of my long term goals with the project involve writing code that can run on low end embedded platforms that may not have the C++ standard library available to it. So I had two main goals:
1. Create a system where C# could be run on very low end systems (esp32, arduino, etc...) 2. Allow the C# code to be easily referenced in a non-C# project for platforms that don't allow it.
So I ended up making my own system, as il2cpp and others didn't quite fit some of these bills. I targetted C to make sure that any C compiler could be used, so if an embedded platform has a custom gcc based compiler it could still be used (I think that's the case with the compiler that PVSnesLib uses for its `tcc` compiler).
Presumably the fact that you don't have to use C.
Does the SNES not have enough RAM to be worth it or did you just not port the heap allocator? Or is there some other reason?
One thing it potentially buys you (besides things mentioned in other posts) is faster iteration cycles.
The C stubbed methods can potentially be populated with logic that sets up a fake SNES logic in it, and makes calls to a custom rendering and input handling (monogame calls for example).
This means you can test a bunch of your logic in a monogame app for easier logic debugging, then use the transpiler to test it on a real system.
I might need to play with this; I have been looking for an excuse to play with the retro console homebrew scene, this seems like as good an excuse as any.
Huh, interesting idea with the `Self` generic dependency for the `Create<T>`. That's an interesting angle I hadn't thought of, thanks.
Also the pvsneslib docs will probably be crucial for working with the SNES in general.
The Maven 2 SNES emulator was pretty useful for debugging. If you are on windows there's also a no$sns emulator that pvsnseslib has console message support for debugging.
I'm not going to promise it's a super polished effort in its current state :)