https://github.com/clownacy/clownlzss

Collection of compressors, built upon a small and simple graph-based LZSS framework.
https://github.com/clownacy/clownlzss

ansi-c c89 c90 compression compressor cpp20 framework library lzss sega sega-genesis sega-mega-drive

Last synced: 2 months ago
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Collection of compressors, built upon a small and simple graph-based LZSS framework.

• Host: GitHub
• URL: https://github.com/clownacy/clownlzss
• Owner: Clownacy
• License: 0bsd
• Created: 2018-12-04T23:12:16.000Z (about 6 years ago)
• Default Branch: master
• Last Pushed: 2024-09-02T19:58:22.000Z (4 months ago)
• Last Synced: 2024-10-12T17:21:50.541Z (2 months ago)
• Topics: ansi-c, c89, c90, compression, compressor, cpp20, framework, library, lzss, sega, sega-genesis, sega-mega-drive
• Language: C++
• Homepage:
• Size: 1.01 MB
• Stars: 25
• Watchers: 7
• Forks: 3
• Open Issues: 1
• Metadata Files:
  • Readme: README.md

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README

        
clownlzss is a lightweight, minimalist, graph-based LZSS framework.

Also included are a collection of compressors which utilise the framework.

Formats supported by the supplied utilities include:

- Kosinski - a compression format common to first-party Sega Mega Drive games

- Saxman - a format used by Sonic the Hedgehog 2, to compress its sound engine

  and music data (is actually a lightly-modified version of Haruhiko Okumura's

  1989 LZSS format)

- Chameleon - a format that saw use in Kid Chameleon and Sonic the Hedgehog 2's

  "Nick Arcade" prototype

- Rocket - a format used by Rocket Knight Adventures

- Rage - a format used by Streets of Rage 2 (is actually RLE, not LZSS)

- Kosinski+ - a modified version of Kosinski developed by the Sonic ROM-hacking

  community, which optimises the format for the Mega Drive's CPU, improving

  decompression speed at no cost to compression ratio

- Faxman - a modified version of Saxman designed to produce smaller files when

  used to compress SMPS music data

- Comper - another community-developed format, which is designed from the

  ground up with a focus on decompression speed on the Motorola 68000. This

  comes at a significant cost to compression ratio

clownlzss utilises graph theory to perform optimal compression: naive "greedy

algorithm" compressors prefer to compress the longest runs possible, but this

does not guarantee the best compression ratio. Graph-based compressors resolve

this by creating an "LZSS graph" - a weighted directed acyclic graph where each

node is a value in the uncompressed file, and each edge is an LZSS match. By

using a shortest-path algorithm, this graph can be used to compute the ideal

combination of matches needed to produce the smallest file.

This project is under the 0BSD licence.