uBlock/src/lib/lz4

Purpose

The purpose of this library is to implement LZ4 compression/decompression, as documented at the official LZ4 repository:

https://github.com/lz4/lz4/blob/dev/doc/lz4_Block_format.md

The files in this directory are developed as a separate project at:

https://github.com/gorhill/lz4-wasm

Files

lz4-block-codec-any.js

The purpose is to instanciate a WebAssembly- or pure javascript-based LZ4 block codec.

If the choosen implementation is not specified, there will be an attempt to create a WebAssembly-based instance. If for whatever reason this fails, a pure javascript-based instance will be created.

The script for either instance are dynamically loaded and only when needed, such that no resources are wasted by keeping in memory code which won't be used.

lz4-block-codec-wasm.js

This contains the code to instanciate WebAssembly-based LZ4 block codec. Note that the WebAssembly module is loaded using a same-origin fetch, hence ensuring that no code outside the package is loaded.

lz4-block-codec-js.js

This contains the code to instanciate pure javascript-based LZ4 block codec.

This is used as a fallback implementation should WebAssembly not be available for whatever reason.

lz4-block-codec.wasm

This is the WebAssembly module, loaded by lz4-block-codec-wasm.js using a same-origin fetch.

lz4-block-codec.wat

The WebAssembly source code used to generate the WebAssembly module lz4-block-codec.wasm.

wat2wasm ./lz4-block-codec.wat -o ./lz4-block-codec.wasm
wasm-opt ./lz4-block-codec.wasm -O4 -o ./lz4-block-codec.wasm

You can get wat2wasm at https://github.com/WebAssembly/wabt, and wasm-opt at https://github.com/WebAssembly/binaryen.