markstreet/conker repository overview

⁠Conker's Bad Fur Day Decompilation

A WIP decompilation of Conker's Bad Fur Day.

Note: To use this repository, you must already have a copy of the game.

⁠Building

Place the US Conker's Bad Fur Day ROM in the root of this repository, name it baserom.us.z64.

Preamble

The assumption is that you will be using Docker⁠ for the building process. If this is not the case, see the Dockerfile⁠ for the prerequisites; the steps below work perfectly well in Ubuntu 20.04 running via WSL on Windows.

See the Quickstart⁠ for more information.

Clone repository

git clone https://github.com/mkst/conker.git --recursive
cd conker

Build Docker image (optional)

docker build . -t conker

Spin up the image interactively (optional)

docker run --rm -ti -v $(pwd):/conker conker bash

Sanity check ROM checksum

make check

Extract ROM

make extract

Decompress code (optional)

make -C conker extract

Compile code (optional)

make -C conker --jobs

Replace compiled code (optional)

make -C conker replace

Compile ROM

make --jobs

If everything matches, you will be greeted with an OK:

build/conker.us.z64: OK

⁠Progress

This project is in its infancy; there are multiple tasks being worked on:

• Converting disassembly into (byte-perfect) C code
• Extracting assets from the ROM and being able to successfully re-pack them
• Identify and document all asset types used in the ROM
• Tooling to support the above tasks

⁠Open issues

• Identifying and documenting Conker asset (model/texture/sound) format

⁠ROM layout

The layout of the ROM is still a work-in-progress. There are a number of sections within the ROM that are compressed with gzip⁠ but have the standard header/trailer stripped and, instead, replaced with a 4-byte header containing the uncompressed data length. These sections are dubbed rzip.

Overview of US ROM shown below:

[header]  0000 0000 > 0000 0040 ; suggests libultra 2.0G
[ boot ]  0000 0040 > 0000 1000 ;
[ code ]  0000 1000 > 0004 2C50 ; init + libultra .text
[ ???? ]  0002 90D0 > ???? ???? ;
[ data ]  0002 C750 > 0002 C7A0 ; init + libultra .data
[ ???? ]  0002 C7A0 > 0004 2C50 ; μcode
[ rzip ]  0004 2C50 > 0018 6B50 ; game .text (compressed)
[ rzip ]  0018 8328 > 0019 C7D8 ; game .data (compressed)
[ code ]  0019 EA88 > 001A 2190 ; debugger .text
[ data ]  001A 2190 > 001A 37E0 ; debugger .data
[ rzip ]  001A 37E0 > 00AB 1950 ; compressed section (textures?)
[ offs ]  00AB 1950 > 00AB 1A40 ; table of asset offsets
[ rzip ]  00AB 1A40 > 03F8 B800 ; assets 00 thru assets 1C
[ ffff ]  03F8 B800 > 0400 0000 ; 0xff padding

⁠Compressed section(s)

There are a number of compressed sections within the ROM. The decompression/compression method is understood and generates matching results.

⁠Building ROM

Due to the compressed code sections, all code segments within the ROM are cut from the ROM and combined together, creating a sub-project inside the conker/ directory.

See the README⁠ for more information.

⁠Tools

⁠Custom tools

• rarezip/rareunzip; python script to compress/decompress the compression format used in the ROM.

NOTE: gzip is used for compression rather than zlib; use the binary in tools/ in order to get matching compression.

⁠Existing tools

This repo makes use of the following open-source tools without which, there would be no decomp:

• asm-differ⁠; compare assembly against the original ROM
• asm-processor⁠; allow GLOBAL_ASM wrappers to include assembly within the c files
• n64splat⁠; split up the rom & much more...
• ido-static-recomp⁠; IDO compiler
• gzip⁠; gzip; specifically with the pre-1.5 memzero behaviour

⁠Contributing

The wiki⁠ will eventually contain discoveries as they are made.

In the meantime, if you wish to contribute in any way, get stuck in and raise a PR or find me on Discord mkst#4741.