This document attempts to be a learning reference to ‘attack’ compression in a game, from start to
finish, with all the (minimum required) theory followed by practical examples. All of the steps and explanations are applied to an actual project with actual screenshots of the project.
References will be given when required, you can use them to dive deeper. But rest assured, you
will only need the tools used in each step to follow along. You can just read this paper without any
extra material if your only goal is to learn about the process.
You must know that each section of this document can be read standalone. If you want to read
only one section, don’t be afraid to do so, however, you will benefit from reading all.
* Note: The actual extraction/reinsertion from/to the ROM won’t be detailed here. If you need a hint
for that, just mind the offset to extract or reinsert bytes and copy them in or out.
The end goal is to understand and be able to use and export the knowledge to do this process, not
to parrot. Remember: Curiosity leads to knowledge, be curious
- This doc (design and all images) was made (written) and redacted by Bunkai.
- First of all, thanks to the devs of the game, this doc wouldn't exist without it.
- Thanks to Abridgewater and YasaSheep for their phenomenal documents on the
Compression Data Analisis (and their help when I asked), without them this doc might not
exist or would have taken way longer.
- Thanks to Phonymike for his help on explaining and commenting most of the ASM
routine to me. This was done two years ago, but as you see, it was well worth it.
- Thanks to 343 for coding the compression and decompression tools, and for virtually
being a partner in those stages. All the python code written in this doc is his,
My own was a work in progress dropped when he beat me to do it.
Hopefully this paper helps many people out there, so thanks to you, readers for reading
and sharing my words.
