oot-gc

A work-in-progress decompilation of the N64 emulator used in the GameCube releases of The Legend of Zelda: Ocarina of Time.

Supported versions:

• mq-j: Master Quest - Japan
• mq-u: Master Quest - North America
• mq-e: Master Quest - Europe/Australia
• ce-j: Collector's Edition - Japan
• ce-u: Collector's Edition - North America
• ce-e: Collector's Edition - Europe/Australia

Currently the decompilation mainly targets the ce-j version, as the Collector's Edition disks also contain an ELF file where symbols and other debugging information were left unstripped.

Building

Requirements

You will need the following dependencies:

• git
• ninja
• python3
• wine (for macOS or non-x86 Linux)
• clang-format (optional)

Ubuntu/Debian

You can install the dependencies with the following commands:

sudo apt-get update
sudo apt-get install git ninja python3

macOS

You can install dependencies via Homebrew with the following command:

brew install git ninja python3
brew install --cask --no-quarantine gcenx/wine/wine-crossover

Instructions

1. Clone the repo using git clone https://github.com/zeldaret/oot-gc.

2. Extract the following TGC archive containing the N64 emulator from the disc of the version you want to build:

• mq-j: zlj_f.tgc
• mq-u: zlj_f.tgc
• mq-e: zlj_f.tgc
• ce-j: 120903_zelda.tgc
• ce-u: zelda_ENG_090903.tgc
• ce-e: zelda_PAL_093003.tgc

Then, extract the DOL file from the TGC archive and place it in the repo as orig/<version>/main.dol. You can use Dolphin to perform both of these extraction steps: right click on the file you want to extract from, select Properties, and go to the Filesystem tab.

3. Run python3 configure.py.

4. Run ninja to build the ce-j version, or run ninja <version> to build another version.

Development Tools

Scripts

• ./dol-diff <version> will run dtk dol diff to show the first differing symbol if the build does not match.
• ./dol-apply <version> will run dtk dol apply to sync symbols (e.g. if a function was renamed in the repo).
• ./format will format all source files with clang-format.

objdiff

For local decompilation testing, start the objdiff GUI and open this directory as the project directory. Currently objdiff may not work properly on files using asm-processor (i.e. files with asm_processor=True in configure.py).

asm-differ (diff.py)

First, copy a matching build to the expected/ directory to diff against:

mkdir expected
cp -r build expected/

Then run e.g. ./diff.py -mwo3 xlMain to diff a function for ce-j, or e.g. ./diff.py -mwo3 xlMain -v mq-j to diff a function for another version.

decomp.me

Run tools/decompme.py <c-file> <asm-file> (e.g. tools/decompme.py src/emulator/cpu.c asm/non_matchings/cpu/cpuExecute.s) to create a decomp.me scratch for a function. The C file and all of its included headers will be used as the context.

Permuter

To import a function for decomp-permuter, ensure powerpc-eabi-objdump binary is on your PATH (for instance by adding tools/binutils from this project) and run something like

path/to/permuter/import.py src/emulator/THPRead.c asm/non_matchings/THPRead/Reader.s
path/to/permuter/permuter.py nonmatchings/Reader -j 8

Sometimes you may need to tweak the source in order for things to import correctly, for example by explicitly marking auto-inlined functions as inline.

Debug Info

The files in the debug/ directory contain a dump of the DWARF debugging information in the original ELF. Functions marked as // Erased were present at one time but have been stripped by the linker, because they were either unused or inlined at all call sites.