Because readable and maintainable code is key. The x is an easily verifiable and portable lossless data compressor. Source codes count 700 lines in total. A core library is less than 400 lines in pure C.
Benchmark evaluates the compression of the reference enwik8 file. All compressors have been compiled with GCC 9.2 on 64-bit Linux. The reference system uses an AMD Ryzen Threadripper 2990WX. All measurements use default settings (no extra arguments). The elapsed Compression and Decompression times (wall clock) are given in seconds. The compression Ratio is given as uncompressed/compressed (more is better). SLOC means Source Lines Of Code. Bold font indicates the best result.
| Compressor | Ratio | Compression time | Decompression time | SLOC |
|---|---|---|---|---|
| lz4 1.9.2 | 1.75 | 0.29 | 0.11 | 20 619 |
| lzop 1.04 | 1.78 | 0.36 | 0.33 | 17 123 |
| x | 1.88 | 1.03 | 0.91 | 700 |
| gzip 1.9 | 2.74 | 4.69 | 0.63 | 48 552 |
| zstd 1.3.7 | 2.80 | 0.55 | 0.18 | 111 948 |
| bzip2 1.0.6 | 3.45 | 7.39 | 3.36 | 8 117 |
| xz 5.2.4 | 3.79 | 53.70 | 1.40 | 43 534 |
| brotli 1.0.7 | 3.88 | 3:05.59 | 0.34 | 35 372 |
The x uses an adaptive Golomb-Rice coding based on context modeling. The context model uses a single previous byte in the uncompressed stream to predict the next byte. The compressor can switch between fast compression mode (default) and multi-pass high compression mode.
make BUILD=release
or
make build-pgo
Compress:
./x INPUT-FILE [OUTPUT-FILE]
Decompress:
./unx INPUT-FILE [OUTPUT-FILE]
- David Barina, ibarina@fit.vutbr.cz
This project is licensed under the MIT License. See the LICENSE.md file for details.