Sonic Advance 2

This is a work in progress matching decompilation of Sonic Advance 2

It so far builds the following ROMs:

• sa2.gba sha1: 7bcd6a07af7c894746fa28073fe0c0e34408022d (USA) (En,Ja,Fr,De,Es,It)
• sa2_europe.gba sha1: b0f64bdca097f2de8f05ac4c8caea2b80c5faeb1 (Europe) (En,Ja,Fr,De,Es,It)
• sa2_japan.gba sha1: dffd0188fc78154b42b401398a224ae0713edf23 (Japan) (En,Ja,Fr,De,Es,It) (:warning: Work in Progress)

Current state

• 🎉 The build is shiftable! You can make any code or asset additions/modifications you like, and most aspects of the game will continue to function.
• Assembly code extracted, disassembled, and somewhat categorised
• All libraries decompiled to C or referenced from agbcc
• Most aspects of the game, including all interactables, have been decompiled to matching C code. Most have not been fully documented, but major functions are.
• All songs have been extracted, and documented as matching MIDI files
• All sprite animation frames have been extracted to PNGs and are used to build the matching rom
• Most tilemaps (backgrounds) have been documented and had their tiles extracted

Community

Join us on discord to get started in helping out

Setting up the repository

Provide assets

You must have a copy of the Sonic Advance 2 (USA) ROM named baserom.gba in the repository root directory.

Dev container

If you use vscode then consider using the provided Dev Container which skips the requirement for any setup. This requires docker is installed on your system. Once running, skip to Build the rom

Install system requirements (without dev container)

On Linux systems

sudo apt install binutils-arm-none-eabi gcc-arm-none-eabi libpng-dev xorg-dev

On MacOS and Windows install devkitARM

Install agbcc into the repo

Clone the agbcc repo into another folder

Inside the agbcc repo and run ./build.sh and then install the compiler in this repo ./install.sh path/to/sa2

Build the rom

On Linux and MacOS, run make in the root of the repo to build.

On Windows you can build using make in the MSYS environment provided with devkitARM.

This command will also build all the required tooling in the tools directory. The tools directory contains a bunch of tooling (built by pret) which is used to build assets and create a matching rom.

If the rom built successfully you will see this output

sa2.gba: OK

NOTE: You can significantly speed up initial build times by passing the number of processes you wish to use for the build make -j<number>

Code formatting

All C code in this repo is formatted with clang-format-13. If using the Dev Container this is installed automatically.

To format code run make format

Notes

• The Kirby & The Amazing Mirror decompilation uses a very similar codebase, as it was written by the same dev team (Dimps)
• https://decomp.me is a great resource for helping to create matching functions
• ldscript.txt tells the linker the order which files should be linked
• For more info, see the FAQs section of TMC

Credits

• Shout out to @froggestspirit for the drive to set this project up
• Special thanks to @normmatt for the initial repo setup and sounds decompilation
• JaceCear for his dedication to understanding the internals of the graphics engine and writing tools to extract this data, as well as massive effort in contributing towards the decompilation process
• Pokemon Reverse Engineering Team for their help with the project, and tooling for GBA decompilations
• Kermalis for their tool which was used to dump the game midis
• 琪姬 for their exellent work documenting all the quirks of matching midis