howto-wasm-minimal

How to create minimal wasm module - PoC

Goals

• use no Emscripten or any libs
• simple toolchain, compile to wasm in a single step
• wasm may use memory prepared by JavaScript
• do something relative compute-intensive
• do something visible

Mystic issue

Symptom: on some systems, the linker may hang, or produce output file with correct size but full of zeros (that's why build script contains a hexdump as last step).

Solution: update your linker.

More info: https://stackoverflow.com/questions/71573019/cant-compile-to-wasm-on-linux

Install

You need CLANG and CLANG's linker (LLD). Tested on versions 13 and 14.

Debian nightly pacakges: https://apt.llvm.org/

On MacOS, you should install CLANG from homebrew. More info on Mac troubleshooting: https://til.simonwillison.net/webassembly/compile-to-wasm-llvm-macos

On Windows, you may use Chocolatey package manager to install CLANG: https://chocolatey.org/

Summary

Why WASM?

Writing web app in any language which is not JavaScript is just pure joy.

Try it

The color change and the blur effect is a WASM module, written in C:

http://linkbroker.hu/stuff/howto-wasm-minimal/