# n64
Experimental low-level N64 emulator written in C and a bit of C++.

Still under heavy development and not ready for prime time. Compatibility is not high and performance is not great (yet.)

The goals of this project are to create a low-level emulator with good compatibility, while learning a lot along the way.

![Build](https://github.com/Dillonb/n64/workflows/Build/badge.svg)
[![Documentation Status](https://readthedocs.org/projects/n64/badge/?version=latest)](https://n64.readthedocs.io/?badge=latest)

![Mario Face](https://media.githubusercontent.com/media/Dillonb/n64/master/screenshots/mario.png)

# Links
- [TODO List](https://github.com/Dillonb/n64/projects/1)
- [Compatibility List](https://github.com/Dillonb/n64/projects/2)
- [My Test Suite](https://github.com/dillonb/n64-tests)
- [My Documentation](https://n64.readthedocs.io/)

# Goals
- Reasonably accurate low-level emulation
- Decent performance. Because this is a low-level emulator, it will never be as fast as high-level emulators.
- Reasonable amount of automated testing
  
# Features
- Keyboard and gamepad support
- GDB stub for debugging

# Limitations & TODOs
- Only Linux is currently supported, as I use Linux-specific features. This is planned to be fixed.
- The dynamic recompiler currently only supports x86_64 with the System-V calling convention. Microsoft's x86_64 calling convention, as well as aarch64 support is planned.
- Only little-endian host platforms are planned to be supported.
- Only gcc and clang will be supported. I unapologetically use extensions like case ranges and binary literals.
- Only software that uses NTSC video modes is currently supported. This is planned to be fixed.

# Building
Currently, only Linux on x86_64 is supported.

1. Install dependencies: SDL2, Vulkan, and optionally Capstone
2. Run the following commands:
```bash
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make
```


# Running
Run with no parameters to use the default settings and load your ROM using the GUI, or run with options:

```
./n64 [OPTION]... [FILE]
n64, a dgb n64 emulator

  -v, --verbose             enables verbose output, repeat up to 4 times for more verbosity
  -h, --help                Display this help message
  -i, --interpreter         Force the use of the interpreter
  -r, --rdp                 Load RDP plugin (Mupen64Plus compatible) - note: disables UI and requires ROM to be passed on the command line!
  -m, --movie               Load movie (Mupen64Plus .m64 format)
  -p, --pif                 Load PIF ROM

https://github.com/Dillonb/n64
```

# Progress

## CPU
An interpreter and a basic dynamic recompiler are available, able to be switched at launch time with a command line flag.

The dynamic recompiler currently only supports the System-V calling convention.

## RSP
Reasonably complete, enough for most games to run.

Hardware-verified over the EverDrive 64's USB port using [rsp-recorder](https://github.com/dillonb/rsp-recorder).

Still greatly in need of optimization.

## RDP
Very early stage. [parallel-rdp by Themaister](https://github.com/Themaister/parallel-rdp) is integrated to provide RDP functionality in the meantime.

# Credits
- [Stephen Lane-Walsh](https://github.com/whobrokethebuild) for [cflags](https://github.com/whobrokethebuild/cflags), [gdbstub](https://github.com/WhoBrokeTheBuild/gdbstub), and moral support
- [@wheremyfoodat](https://github.com/wheremyfoodat) for his help with x86 assembly and moral support
- [Giovanni Bajo](https://github.com/rasky/) for his automated RSP tests
- [Peter Lemon](https://github.com/peterlemon/) for his tests, and permission to use his ASM code and font as a template for my own tests

# Libraries Used
- [DynASM](https://luajit.org/dynasm.html) as the emitter for the dynamic recompiler
- [SDL2](https://www.libsdl.org/) for graphics, audio, and input
- [Capstone](http://www.capstone-engine.org/) as a MIPS disassembler for debugging
- [parallel-rdp](https://github.com/Themaister/parallel-rdp) as the RDP until I write my own
- [Dear Imgui](https://github.com/ocornut/imgui) for the GUI