Here is a Nemesis compressor and decompressor that I made. Notably, this compresses data identically to Sega's original Nemesis compressor. This is useful for disassemblies, as it allows assets to be stored uncompressed for ease of viewing and editing without causing the built ROM to become inaccurate due to differences in compression. The compressor also has an option to compress data better than Sega's compressor, though the compressed data will no longer be accurate to it. Currently this improved compression makes compressed data 1% smaller. clownnemesis is written in ANSI C and its licence is 0BSD. Download: https://github.com/Clownacy/clownnemesis/releases Combined with my accurate Kosinski compressor and the rediscovered original Saxman compressor, 3 out of the 4 main Sonic compression formats now have accurate compressors!
I have fixed an inaccuracy that would affect padding bytes along with another inaccuracy that would cause S3K's Buggernaut tiles to compress inaccurately. An update that contains these fixes can be found here. I have extended the compressor's test suite to include Sonic 3 & Knuckles. Now every(?) Nemesis file in that game has been tested to recompress accurately also.
