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Table of Contents

Project Description

This project is to port Jak 1 (NTSC, "black label" version) to PC. Over 99% of this game is written in GOAL, a custom Lisp language developed by Naughty Dog. Our strategy is:

  • decompile the original game code into human-readable GOAL code
  • develop our own compiler for GOAL and recompile game code for x86-64
  • create a tool to extract game assets into formats that can be easily viewed or modified
  • create tools to repack game assets into a format that our port uses.

Our objectives are:

  • make the port a "native application" on x86-64, with high performance. It shouldn't emulated, interpreted, or transpiled.
  • Our GOAL compiler's performance should be around the same as unoptimized C.
  • try to match things from the original game and development as possible. For example, the original GOAL compiler supported live modification of code while the game is running, so we do the same, even though it's not required for just porting the game.
  • support modifications. It should be possible to make edits to the code without everything else breaking.

We support both Linux and Windows on x86-64.

Getting Started - Linux (Ubuntu)

Install packages and init repository:

sudo apt install gcc make cmake build-essential g++ nasm clang-format
git submodule update --init --recursive

Compile:

cmake -B build && cmake --build build -j 8

Run tests:

./test.sh

Note: we have found that clang and lld are significantly faster to compile and link than gcc, generate faster code, and have better warning messages. To install these:

sudo apt install lld clang

and run cmake (in a fresh build directory) with:

cmake -DCMAKE_SHARED_LINKER_FLAGS="-fuse-ld=lld" -DCMAKE_EXE_LINKER_FLAGS="-fuse-ld=lld" -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ ..

this decreases the compile and link time from ~10 seconds to ~4 seconds.

Getting Started - Linux (Arch)

Install packages and init repository:

sudo pacman -S gcc make cmake base-devel g++ nasm
git submodule update --init --recursive

Compile:

cmake -B build && cmake --build build -j 8

Run tests:

./test.sh

Getting Started - Nixpkgs

If your Nix supports flakes:

nix develop # development environment
nix build # package
nix develop '.#jak-asan-dev' # development environment with Clang
nix build '.#jak-asan' # package with Clang ASan build

Otherwise, with traditional Nix:

nix-shell # development environment
nix-build # package
nix-shell -A packages.x86_64-linux.jak-asan-dev # development environment with Clang
nix-build -A packages.x86_64-linux.jak-asan # package with Clang ASan build

Getting Started - Windows

Install Visual Studio 2019 and get the C++ and CMake tools via the Visual Studio Installer

On Windows, it's recommended to get Scoop to use as a package manager, making the follow steps much easier. Follow the steps on the bottom of the homepage here https://scoop.sh/

Once Scoop is installed, run the following command:

scoop install llvm nasm

Initialize the repository's third-party dependencies:

git submodule update --init --recursive

Open the project as a CMake project, browse for the root level CMakeLists.txt:

In the toolbar, you should be able to select an individual component to compile, or combine within the root CMakeLists.txt. In the future we will pre-define configurations to make this easier.

You may also wish to view the files that pertain to each CMake target, rather than the project as it is normally:

Project Layout

There are four main components to the project.

The first is goalc, which is a GOAL compiler for x86-64. Our implementation of GOAL is called OpenGOAL. All of the compiler source code is in goalc. To run the compiler on Linux, there is a script gc.sh. The compiler is controlled through a prompt which can be used to enter commands to compile, connect to a running GOAL program for interaction, run the OpenGOAL debugger, or, if you are connected to a running GOAL program, can be used as a REPL to run code interactively. In addition to compiling code files, the compiler has features to pack and build data files.

The second component to the project is the decompiler. You must have a copy of the PS2 game and place all files from the DVD into the iso_data folder. Then run decomp.sh to run the decompiler. The decompile will extract assets to the assets folder. These assets will be used by the compiler when building the port. The decompiler will output code and other data intended to be inspected by humans in the decompiler_out folder. Stuff in this folder will not be used by the compiler.

The third is the game source code, written in OpenGOAL. This is located in goal_src. All GOAL and GOOS code should be in this folder. Right now most of this is placeholders, but you can take a look at kernel/gcommon.gc or goal-lib.gc to see some in-progress source code.

The final component is the "runtime", located in game. This is the part of the game that's written in C++. In the port, that includes:

  • The "C Kernel", which contains the GOAL linker and some low-level GOAL language features. GOAL has a completely custom dynamically linked object file format so in order to load the first GOAL code, you need a linker written in C++. Some low-level functions for memory allocation, communicating with the I/O Processor, symbol table, strings, and the type system are also implemented in C, as these are required for the linker. It also listens for incoming messages from the compiler and passes them to the running game. This also initializes the game, by initializing the PS2 hardware, allocating the GOAL heaps, loading the GOAL kernel off of the DVD, and executing the kernel dispatcher function. This is in the game/kernel folder. This should be as close as possible to the game, and all differences should be noted with a comment.

  • Implementation of Sony's standard library. GOAL code can call C library functions, and Naughty Dog used some Sony library functions to access files, memory cards, controllers, and communicate with the separate I/O Processor. The library functions are in game/sce. Implementations of library features specific to the PC port are located in game/system.

  • The I/O Processor driver, Overlord. The PS2 had a separate CPU called the I/O Processor (IOP) that was directly connected to the DVD drive hardware and the sound hardware. Naughty Dog created a custom driver for the IOP that handled streaming data off of the DVD. It is much more complicated than I first expected. It's located in game/overlord. Like the C kernel, we try to keep this as close as possible to the actual game.

  • Sound Code. Naughty Dog used a third party library for sound. We have not started on this yet.

  • PC specific graphics stuff. We have not started on this yet.

Directory Layout

  • .github: GitHub actions CI setup
  • .vs: Visual Studio project configurations
  • assets: extracted assets (textures, translated game text) generated by the decompiler. Not included in the repository. To be used when building the PC port.
  • build: C++ CMake build folder
  • common: common C++ code shared between the compiler, decompiler, and game.
    • cross_os_debug: platform-independent library for implementing the OpenGOAL debugger. Linux-only currently
    • cross_sockets: platform-independent library for sockets. Used to connect the compiler to a running game. Linux and Windows.
    • goos: the compiler-time macro language and parser for OpenGOAL.
    • type_system: the OpenGOAL type system
    • util: Random utility functions for accessing files, timers, etc.
  • decompiler: Source code for the decompiler
    • config: JSON config files for the decompiler and type definition file.
    • data: utilities to extract assets from the game
    • Disasm: MIPS disassembler
    • Function: Tools for analyzing GOAL functions
    • gui: an early prototype of a Python GUI for reading the output of the decompiler
    • IR: the "Intermediate Representation" for GOAL functions
    • ObjectFile: Utilities for processing the GOAL object file format.
    • scripts: Useful scripts for setting up the decompilation
    • util: random utilities
  • decompiler_out: output of the decompiler that's not automatically used by the compiler. This is for humans to read and use. Not included in the repository.
  • doc: more documentation!
  • game: the source code for the game executable
    • common: shared stuff between the kernel and overlord
    • kernel: the part of the GOAL kernel written in C. The entry point for the game is in kboot.cpp.
    • overlord: the I/O processor driver used to get data off of the DVD
    • sce: the Sony library implementation
    • system: PC-port specific stuff
  • goal_src: The GOAL code for the game. It's mostly empty now.
    • build: info related to the GOAL build system.
    • engine: the game engine
    • kernel: The GOAL kernel
    • levels: Level specific code.
  • goalc: The OpenGOAL compiler
    • compiler: The implementation of the OpenGOAL language
    • data_compiler: Tools for packing data
    • debugger: The OpenGOAL debugger (part of the compiler)
    • emitter: x86-64 emitter and object file generator
    • listener: The OpenGOAL listener, which connects the compiler to a running GOAL program for the interactive REPL
    • regalloc: Register allocator
  • iso_data:
  • out: Outputs from the build process. Only the iso subfolder should contain assets used by the game.
    • iso: Final outputs that are used by the game.
    • obj: Object files generated by the compiler.
  • resources: To be removed. Contains fake versions of some files required to get things booting.
  • scripts: Utility scripts.
  • test: Unit tests (run on GitHub Actions)
  • third-party: Third party libraries
    • CMake Code Coverage. For code coverage statistics on GitHub builds
    • fmt. String formatting library
    • googletest: Test framework
    • inja: templating library used for generating test code for compiler tests
    • minilzo: decompression code for Jak 2 and later DGOs
    • mman: Windows library used to emulate mmap on Linux
    • run-clang-format: Utility to check and enforce code formatting
    • run-clang-tidy
    • zydis: x86-64 disassembler used in the OpenGOAL debugger
    • json: A JSON library
    • replxx: Used for the REPL input. Support history and useful editing shortcuts.
    • svpng: Save a PNG file

More Documentation

Check out these files for more documentation. Some of it is still in progress

  • doc/goal_dbg_doc.md: OpenGOAL debugger
  • doc/goal_doc.md: OpenGOAL language
  • doc/reader.md: OpenGOAL "reader" documentation (OpenGOAL syntax)
  • doc/type_system.md: OpenGOAL type system documentation
  • doc/porting_to_x86.md: Summary of changes we're making to port to x86-64
  • doc/goos.md: GOOS macro language

ASan Build

The project supports building with Address Sanitizer (https://github.com/google/sanitizers/wiki/AddressSanitizer) in Linux.

export CXX=clang++
cmake .. -DASAN_BUILD=TRUE

You will have to delete the build folder when changing compilers. When running cmake, you should see something like:

-- The CXX compiler identification is Clang 10.0.0
...
-- Doing ASAN build

Then you can run the tests, runtime, and compiler as normal and they will abort if ASan finds an error.

On Windows / Visual Studio

Until 16.9 Preview 4, when attaching a debugger to the ASan build, you must disable breaking on Win32 Access Violation exceptions. See the relevant section Debugging - Exceptions here https://devblogs.microsoft.com/cppblog/asan-for-windows-x64-and-debug-build-support/#known-issues