hhy5277 / wasm-fun

Non-trivial programs in hand-written WebAssembly

wasm-fun

Non-trivial programs in hand-written WebAssembly

This repo is a collection of useful algorithms written from scratch in WebAssembly text format (.wat) and assembled to .wasm via wabt.

See Overview section for a list of programs included. See wat folder for the fully-commented and well-explained source code. See wasm for compiled binaries you can grab and use (with your JS projects). See tests for usage examples.

Despite that the algorithms are non-trivial, the assembled binaries are extremely small (compared to say what you get from emscripten)! Average file size is ~900 bytes.

Motivation

I find WebAssembly a wonderful technology, and have been compiling C's and C++'s to wasm via emscripten for many projects. So I thought I should learn at least learn the "real" thing -- coding in WebAssembly directly. Fortunately, the lisp-like S-expressions makes the language quite pleasant to work with.

I haven't found many handwritten examples beyond the "fizzbuzz" and the "99 beers". (This Conway's Game of Life in WebAssembly gave me a lot of inspiration though). So I started my own little collection of algorithms I enjoyed, in hand-written WebAssembly, with ample comments and explanations for the reader.

I think WebAssembly is the sort of language where the beauty is derived from its simplicity.

Overview

	thinning.wat
	Skeletonization/thinning of binary images. Implements Zhang-Suen (1984). Paper
	disttransform.wat
	Compute distance transform of binary images. Implements Meijster distance. Paper
	findcontours.wat
	Trace contours from binary images (vector output). This is the same as OpenCV's findContours. Implements Suzuki-Abe (1983). Paper
	browniantree.wat
	Generate brownian fractal trees (aka Diffusion-limited aggregation).
	mazegen.wat
	Generate mazes using Wilson's algorithm, which guarantees an unbiased sample from the uniform distribution over all mazes.
	malloc.wat
	Very baseline 32-bit implicit-free-list first-fit malloc.
	traceskeleton.wat
	Retrieve topological skeleton as a set of polylines from binary images. Original algorithm. Includes a malloc implementation and a linked list implementation. ~300% faster than the version complied with emscripten (and ~10x smaller), ~500% faster than vanilla Javascript.
	containers.wat
	Implements STL-like polymorphic container types arr<T> (continous resizable array), list<T> (doubly linked list) and map<T,T> (hash table).
	random.wat
	Uniform, Perlin, Gaussian, and exponential randomness.