Owez / rle

A simple run-length-encoding implementation for light compression

Run-length-encoding: rle

A simple run-length-encoding implementation for light compression

Examples

Encoding:

use rle;

fn main() {
    let data = &[44, 43, 6, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 3];
    let compressed = rle::compress(data);

    println!("normal: {}, compressed: {}", data.len(), compressed.len());

    // will show "normal: 16, compressed: 10"
}

Under the hood

This rle library uses a custom run-length-encoding technique in order to get the most efficiant compression results. It achieves this by allowing all repeating characters under 6x through, e.g:

helllllo!

But allows anything 6x or above through, e.g:

hellllllllllllllllllllllllllllllllllllllllllllo!

This is due to the encoding using a u32 under the hood to store the length, which means the it can store up to ~4 billion repeating characters until overflow. A run-length-encoded block would look like the following for the previous example:

[h, e, 4, 0, 0, 0, 44, o, !]

You may assume whatever binary encoding you'd like for these letters to properly expand this block, but in essense it uses an End-of-Transmission character to represent the start of an run-length-encoded block and has a [u8; 4] (which represents the previously mentioned u32 in big-endian form).

After that, it simply has a u8 for the byte it is representing and continued further onwards; looping this compression/decompression until the end of the inputted bytes.