PPMd in native Rust

PPMd compression / decompression. It's a port of the PPMd C-code from 7-Zip to Rust.

The following variants are provided:

• The PPMd7 (PPMdH) as used by the 7z archive format
• The PPMd8 (PPMdI rev.1) as used by the zip archive format

Acknowledgement

This port is based on the 7zip version of PPMd by Igor Pavlov, which in turn was based on the PPMd var.H (2001) / PPMd var.I (2002) code by Dmitry Shkarin. The carryless range coder of PPMd8 was originally written by Dmitry Subbotin (1999).

License

The code in this crate is in the public domain as the original code by their authors.