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clang can compile into wasm pretty well via the --target=wasm32 option. It creates small binaries. My 16-Bit x86 emulator with BIOS and DOS emulation is under

clang can compile into wasm pretty well via the --target=wasm32 option. It creates small binaries. My 16-Bit x86 emulator with BIOS and DOS emulation is under 100kB [0]. [0] https://github.com/s-macke/FSHistory https://github.com/s-macke/FSHistory

ncruces 1y ago
And if you need parts of libc, you can use something like the below, for something more minimal than musl: https://github.com/Photosounder/MinQND-libc https://github.com/Photosounder/MinQND-libc Personally, although I do use wasi-sdk (clang) and the wasm32-unknown-wasi triple, the result can be basically free-standing, depending on what flags you use. As a sibling post said, optimization matters, and using wasm-ctor-eval and wasm-opt also helps. But it's useful to keep full C semantics.
- s-macke 1y ago
  Thanks. This is awesome. For the emulator I wrote my own 200 line libc implementation with a five line malloc routine [0]. Nice to see another implementation, which does a little bit more. [0] https://github.com/s-macke/FSHistory/tree/master/src/wasm_libc_wrapper https://github.com/s-macke/FSHistory/tree/master/src/wasm_li...
- apitman 1y ago
  > Personally, although I do use wasi-sdk (clang) and the wasm32-unknown-wasi triple, the result can be basically free-standing, depending on what flags you use. This is what I've been doing for my little non-WASI runtime. For my minimal programs I find only a few wasi exports are required, which don't appear to actually be used and I just stub them out. Would love to figure out how to get rid of the code depending on them entirely but it's lower priority.
  - ncruces 1y ago
    If it's possible that it's stuff that's being used at initialization time, wasm-ctor-eval might help. Also, you probably want to build a reactor (-mexec-model=reactor) if that's not what you're already doing. A command will use WASI to read command-line arguments and environment. But it's hard to tell without knowing the specific imports you're trying to get rid of.
apitman 1y ago
That emulator is awesome. Especially cool about the easter egg. I've seen a few of these WASM emulators and fantasy consoles, but they all seem to be focused on games. Are you aware of any that are designed to run normal GUI apps?
- s-macke 1y ago
  Maybe WebVM is something you are looking for [0]. [0] https://github.com/leaningtech/webvm https://github.com/leaningtech/webvm
90s_dev 1y ago
I tried for a few days to embed clang as a lib just to get it to compile to wasm and got so close and I might pick that project up again because I think it would be a really exciting and fun app.

ncruces 1y ago

And if you need parts of libc, you can use something like the below, for something more minimal than musl: https://github.com/Photosounder/MinQND-libc https://github.com/Photosounder/MinQND-libc Personally, although I do use wasi-sdk (clang) and the wasm32-unknown-wasi triple, the result can be basically free-standing, depending on what flags you use. As a sibling post said, optimization matters, and using wasm-ctor-eval and wasm-opt also helps. But it's useful to keep full C semantics.

s-macke 1y ago
Thanks. This is awesome. For the emulator I wrote my own 200 line libc implementation with a five line malloc routine [0]. Nice to see another implementation, which does a little bit more. [0] https://github.com/s-macke/FSHistory/tree/master/src/wasm_libc_wrapper https://github.com/s-macke/FSHistory/tree/master/src/wasm_li...
apitman 1y ago
> Personally, although I do use wasi-sdk (clang) and the wasm32-unknown-wasi triple, the result can be basically free-standing, depending on what flags you use. This is what I've been doing for my little non-WASI runtime. For my minimal programs I find only a few wasi exports are required, which don't appear to actually be used and I just stub them out. Would love to figure out how to get rid of the code depending on them entirely but it's lower priority.
- ncruces 1y ago
  If it's possible that it's stuff that's being used at initialization time, wasm-ctor-eval might help. Also, you probably want to build a reactor (-mexec-model=reactor) if that's not what you're already doing. A command will use WASI to read command-line arguments and environment. But it's hard to tell without knowing the specific imports you're trying to get rid of.

apitman 1y ago

That emulator is awesome. Especially cool about the easter egg. I've seen a few of these WASM emulators and fantasy consoles, but they all seem to be focused on games. Are you aware of any that are designed to run normal GUI apps?

s-macke 1y ago
Maybe WebVM is something you are looking for [0]. [0] https://github.com/leaningtech/webvm https://github.com/leaningtech/webvm

90s_dev 1y ago

I tried for a few days to embed clang as a lib just to get it to compile to wasm and got so close and I might pick that project up again because I think it would be a really exciting and fun app.