heartedapp/swiftzstd

Swift wrapper around ZSTD compression lib

SwiftZSTD

Description

Swift Wrapper around Zstandard Compression Library

System Requirements

Zstandard is required to be installed in order to build this package. See https://github.com/facebook/zstd for additional information, including licensing.

On OS X the easiest way to install Zstandard is with homebrew

brew install zstd

On Ubuntu it can be installed with apt

sudo apt install libzstd-dev

Installation

This has been bundled as a swift package for Swift 5. To use it in a project include the pacakge as a dependency in your projects Package.swift:

    dependencies: [
        .package(url: "https://github.com/HeartedApp/SwiftZSTD", .branch("master"))
    ],

In order to test out the included example ZSTDSampleApp run swift run

$ swift run
Testing compression

Original size: 1465 bytes
Compressed size: 757 bytes
Decompressed string is the same as original.

Testing compression with dictionary

Building Dictionary
Original size: 1465 bytes
Compressed size: 438 bytes
Dictionary decompressed string is the same as original.

Limitations

Compression and de-compression of in-memory buffers is supported, with or without a context or a dictionary. Buffers are represented by Data instances that must use contiguous storage, and in practice most Data instances meet this requirement. To be decompressed by this code, a buffer must be a complete frame with decompressed size encoded in it and retrievable using ZSTD_getDecompressedSize().

This is actually a fairly useful implementation. Experimentation shows that even fairly large files (100s of MB),when compressed using the zstd utility provided with the C library, end up in a single frame, which is easily decompressible by this Swift code if read into memory as one piece.