Gallop

A lightweight CM compressor for prototyping built with zig, roughly based on lpaq.
It gallops!

Currently: prediction is bitwise, model is order0-ish (12-bit context) with simple 12-bit counters.

Usage

./gallop c /data/book1 book1.bin
./gallop c book1.bin book1.orig
cmp book1.orig /data/book1

Goals

• Compress book1 in <2 s, enwik8 in <3 mins
• Under 1KLoC (but readable, lpaq style)
• Under 1GB memory usage
• Optimized for compression ratio

TODO

• Add a magic number (I propose b"gllp" = 0x676c_6c70)
• Use (12-bit) states instead of counters
• Add state map
• Match model?
• Delayed counters?
• Entropy hashing?

Build

zig build-exe gallop.zig

References

Roughly based on lpaq. Check out my other compressor weath3rb0i.