Implements the decompression routine (a variant on LZ77 using a 0×800 byte sliding window, distinguishing length-distance pairs from literals by prefixing every group of 8 pairs/literals with a single byte, each bit of which controls whether the next corresponding byte is a literal or a length-distance pair; length-distance pairs are encoded as 2 bytes [abcdefgh ijklmnop] where length is [lmnop] and distance is [ijkabcdefgh]) found at 0xC2FF6D in at least the original Japanese and both English releases of Final Fantasy VI on the SNES.

Also implements a complementary compression routine to generate data that the aforementioned decompression routine will be able to decompress.