x – minimalist data compressor
Why?
Because readable and maintainable code is key. The x is an easily verifiable and portable lossless data compressor. Source codes count 320 lines in total. A core library is less than 250 lines in pure C.
Benchmarks
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 | 320 |
| 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 |
Algorithms
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.
Build
Compile the library and sample application:
$ make
Run simple test:
$ make check
Usage
Compress:
$ ./x < INPUT-FILE > OUTPUT-FILE
Decompress:
$ ./unx < INPUT-FILE > OUTPUT-FILE
License
This project is licensed under the MIT License. See the LICENSE.md file for details.