The Legend of Zelda: Ocarina of Time

- WARNING! -

This repository is a work in progress, and while it can be used to make certain changes, it's still
constantly evolving. If you use it for modding purposes in its current state, please be aware that
the codebase can drastically change at any time. Also note that some parts of the ROM may not be
'shiftable' yet, so modifying them could be difficult at this point.

This is a WIP decompilation of The Legend of Zelda: Ocarina of Time. The purpose of the project is to recreate a source code base for the game from scratch, using information found inside the game along with static and/or dynamic analysis. It is not producing a PC port. For more information you can get in touch with the team on our Discord server.

The only build currently supported is Master Quest (Debug), but other versions are planned to be supported.

It builds the following ROM:

• oot-gc-eu-mq-dbg.z64 md5: 75e344f41c26ec2ec5ad92caa9e25629

Note: This repository does not include any of the assets necessary to build the ROM. A prior copy of the game is required to extract the needed assets.

Website: https://zelda64.dev

Discord: https://discord.zelda64.dev

Installation

We recommend using WSL on Windows, or native Linux, which the rest of this readme describes. We currently have instructions for

• Windows, with and without WSL
• macOS
• Linux, natively or using WSL / VM
• Docker

(These will also depend on the Linux instructions.) Some of these may also be out of date or unmaintained; usually our contributors use WSL, Linux, and macOS, so these instructions should be up to date.

Windows

For Windows 10 or 11, install WSL and a distribution by following this WSL Installation Guide. We recommend using Ubuntu 20.04 as the Linux distribution.

For older versions of Windows, install a Linux VM or refer to either Cygwin or Docker instructions.

Linux (Native or under WSL / VM)

1. Install build dependencies

The build process has the following package requirements:

• git
• build-essential
• binutils-mips-linux-gnu
• python3
• python3-pip
• python3-venv
• libpng-dev

Under Debian / Ubuntu (which we recommend using), you can install them with the following commands:

sudo apt-get update
sudo apt-get install git build-essential binutils-mips-linux-gnu python3 python3-pip python3-venv libpng-dev

If you are using GCC as the compiler for Ocarina of Time, you will also need:

• gcc-mips-linux-gnu

2. Clone the repository

N.B. If using WSL, we strongly encourage you to clone into WSL's Linux filesystem using Linux's git. Cloning into the Windows filesystem will result in much slower read/write speeds, and often causes issues when Windows copies the files with the wrong line endings, which the compiler IDO cannot handle correctly.

Clone https://github.com/zeldaret/oot.git where you wish to have the project, with a command such as:

git clone https://github.com/zeldaret/oot.git

This will copy the GitHub repository contents into a new folder in the current directory called oot. Change into this directory before doing anything else:

cd oot

3. Prepare a base ROM

Place a copy of the Master Quest (Debug) ROM inside the baseroms/gc-eu-mq-dbg/ folder. If you are under WSL, you can run the command explorer.exe . to open the current directory in the Windows file explorer.

Rename the file to baserom.z64, baserom.n64 or baserom.v64, depending on the original extension.

4. Setup the ROM and build process

Setup and extract everything from your ROM with the following command:

make setup

This downloads some dependencies (from pip), and compiles tools for the build process. Then it generates a new ROM baseroms/gc-eu-mq-dbg/baserom-decompressed.z64 that will have the overdump removed and the header patched. It will also extract the individual assets from the ROM.

5. Build the ROM

Run make to build the ROM. Make sure your path to the project is not too long, otherwise this process may error.

make

If all goes well, a new ROM should be built at build/gc-eu-mq-dbg/oot-gc-eu-mq-dbg.z64, and the following text printed:

build/gc-eu-mq-dbg/oot-gc-eu-mq-dbg.z64: OK

If you instead see the following:

build/gc-eu-mq-dbg/oot-gc-eu-mq-dbg.z64: FAILED
md5sum: WARNING: 1 computed checksum did NOT match

This means that the built ROM isn't the same as the base one, so something went wrong or some part of the code doesn't match.

NOTE: to speed up the build, you can either:

• pass -jN to make setup and make, where N is the number of threads to use in the build. The generally-accepted wisdom is to use the number of virtual cores your computer has.
• pass -j to make setup and make, to use as many threads as possible, but beware that this can use too much memory on lower-end systems.

Both of these have the disadvantage that the ordering of the terminal output is scrambled, so for debugging it is best to stick to one thread (i.e. not pass -j or -jN).

Contributing

All contributions are welcome. This is a group effort, and even small contributions can make a difference. Some tasks also don't require much knowledge to get started.

Most discussions happen on our Discord Server, where you are welcome to ask if you need help getting started, or if you have any questions regarding this project and other decompilation projects.