pieviero / th06

Decompilation of 東方紅魔郷　～ the Embodiment of Scarlet Devil (1.02h)

東方紅魔郷　～ the Embodiment of Scarlet Devil

This project aims to perfectly reconstruct the source code of Touhou Koumakyou ~ the Embodiment of Scarlet Devil 1.02h by Team Shanghai Alice.

This project is still highly work in progress and in its early stages.

Installation

Executable

This project requires the original 東方紅魔郷.exe version 1.02h (9f76483c46256804792399296619c1274363c31cd8f1775fafb55106fb852245)

Copy 東方紅魔郷.exe to resources/game.exe.

Dependencies

The build system has the following package requirements:

• python3 >= 3.4
• msiextract (On linux/macos only)
• wine (on linux/macos only, prefer CrossOver on macOS to avoid possible CL.EXE heap issues)
• aria2c (optional, allows for torrent downloads, will automatically install on Windows if selected.)

The rest of the build system is constructed out of Visual Studio 2002 and DirectX 8.0 from the Web Archive.

Configure devenv

Run the following script:

# NOTE: On macOS if you use CrossOver.
# export WINE=<CrossOverPath>/wine
./scripts/create_th06_prefix

Building

Run the following script:

python3 ./scripts/build.py

This will automatically generate a ninja build script build.ninja, and run ninja on it.

Contributing

Reverse Engineering

You can find an XML export of our Ghidra RE in the companion repository th06-re, in the xml branch. This repo is updated nightly through [scripts/export_ghidra_database.py], and its history matches the checkin history from our team's Ghidra Server.

If you wish to help us in our Reverse Engineering effort, please contact @roblabla on discord so we can give you an account on the Ghidra Server.

Reimplementation

The easiest way to work on the reimplementation is through the use of objdiff. Here's how to get started:

1. First, follow the instruction above to get a devenv setup.
2. Copy the original 東方紅魔郷.exe file (version 1.02h) to the resources/game.exe folder. This will be used as the source to compare the reimplementations against.
3. Download the latest version of objdiff.
4. Run python3 scripts/export_ghidra_objs.py --import-xml. This will extract from resources/game.exe the object files that objdiff can compare against.
5. Finally, run objdiff and open the th06 project.

Choosing a function to decompile

The easiest is to look at the config/stubbed.csv files. Those are all functions that are automatically stubbed out. You should pick one of them, open the associated object file in objdiff, and click on the function of interest.

Then, open the correct cpp file, copy/paste the declaration, and start hacking! It may be useful to take the ghidra decompiler output as a base. You can find this output in the th06-re repository.

Credits

We would like to extend our thanks to the following individuals for their invaluable contributions:

• @EstexNT for porting the var_order pragma to MSVC7.