zstddec


ZSTD (Zstandard) decoder for Web and Node.js, using WebAssembly.

Installation

``shell
npm install --save zstddec
`

API

`javascript
import { ZSTDDecoder } from 'zstddec';

const decoder = new ZSTDDecoder();

await decoder.init();

const decompressedArray = decoder.decode( compressedArray, uncompressedSize );
`

> Limitations: The decoder may fail with the error wasm function signature contains illegal type when the uncompressedSize is not known in advance and given to the decode() method. This is presumably a bug in the WASM bindings, which I am not yet sure how to fix.

Contributing

To build the project locally, run:

`
npm install
npm run dist
`

To test changes:

`
npm test
`

Building from source

Compiled from https://github.com/facebook/zstd/tree/dev/build/single_file_libs, with the
following steps:

`shell
./create_single_file_decoder.sh
`

> Note
The current build is based on zstd v1.5.0. The binary sized increased
following this version.

`shell
emcc zstddeclib.c -s EXPORTED_FUNCTIONS="['_ZSTD_decompress', '_ZSTD_findDecompressedSize', '_ZSTD_isError', '_malloc', '_free']" -Wl,--no-entry -s WASM=1 -Oz -g0 -flto -s ALLOW_MEMORY_GROWTH=1 -s FILESYSTEM=0 -s STANDALONE_WASM=1 -DNDEBUG=1 -s PURE_WASI=0 -o zstddec.wasm
base64 -w 0 zstddec.wasm > zstddec.txt
`

> Note
The -w 0 argument is only for the base64 shipped on Linux systems -- on macOS this should be omitted.

The base64 string written to zstddec.txt is embedded as the wasm` variable at the bottom
of the source file. The rest of the file is written by hand, in order to avoid an additional JS
wrapper generated by Emscripten.

License

JavaScript wrapper is provided under the MIT License, and the WASM ZSTD decoder is provided by Facebook under the BSD 3-Clause License.