I wrote a compressor for Miraculum a few months ago, and thought it might be useful for other people...somehow!

The compressor itself is much slower than it really should be, but the data chunks that need to be compressed in Miraculum are fairly
small, so it's not too much of an issue there.

Miraculum uses LZSS with a 256-byte window(8-bit window offsets), 4-bit lengths, and a 1-byte flags byte to mark literals or offsets/lengths.

The format really seems to be suitable for an 8-bit system with limited RAM, especially the PC Engine with its bit-branching instructions.

http://mednafen.sourceforge.net/junk/compress.cpp