Crate lzss[][src]

Expand description

Lempel–Ziv–Storer–Szymanski de-/compression

lzss is a lossless data compression algorithm in pure Rust. This crate is built for embedded systems:

  • Small code size
  • Uses little RAM and CPU
  • no_std feature
  • All parameters can be compile-time only

Generic vs. dynamic

This crate comes in two flavors: generic (Lzss) and dynamic (LzssDyn).

The dynamic one has one compress function and all parameters are passed to it at runtime, making it very adaptive.

The generic one has compile-time parameters will produce a function for each different sets of parameters. This function will be more optimized by the compiler than the dynamic one, the downside is that multiple functions are generated when multiple parameter sets are used.

(The same applies for decompress and other functions, only used function will be in the generated program.)

Lack of a header

This algorithm has by design no header at all. Please be aware that it is not possible to check if the contents is correct, or even the length matches. It is recommended to add a header based on the requirements.

Origin

This code is based on the LZSS encoder-decoder by Haruhiko Okumura, public domain.

In order to create an encoder-decoder which is compatible to the program above the following is required: C = 0x20 in this library and P = (1+EI+EJ) / 9 in Okumuras program.

Features

  • alloc - Enables everything marked with alloc.
  • std - Enables everything marked with std and the Error instance for LzssError and LzssDynError.
  • const_panic - Requires nightly and enables compile-time checks of the parameters, see Lzss.

Usage

With std:

[dependencies]
lzss = "0.8"

With no_std:

[dependencies]
lzss = { version = "0.8", default-features = false }

Example

type MyLzss = Lzss<10, 4, 0x20, { 1 << 10 }, { 2 << 10 }>;
let input = b"Example Data";
let mut output = [0; 30];
let result = MyLzss::compress(
  SliceReader::new(input),
  SliceWriter::new(&mut output),
);
assert_eq!(result, Ok(14)); // there was no overflow and the output is 14 bytes long

Structs

std Read from a stream, this is a inefficient exemplary implementation.

std Write to a stream, this is a inefficient exemplary implementation.

A zero-sized type, the const generics specify the parameters of the compression.

Dynamic parameters for de-/compression (see Lzss for compile-time parameters).

Read from a slice.

A zero-sized type, will be returned in case of an error.

Write into a slice.

Write into a slice which has the exact size of the result.

alloc/std Write into a vector.

Enums

The error returned by LzssDyn::new.

This represents either an read or write error.

Traits

Trait for reading bytes.

Conversion from Result<T, LzssError<Void, Void>> to T.

Conversion from Result<T, LzssError<Void, E>> to Result<T, E>.

Conversion from Result<T, LzssError<E, Void>> to Result<T, E>.

Trait for writing bytes.