rustyboy

rustyboy is a simple Game Boy emulator implemented in Rust. It is currently a WIP - the end goal is get Pokemon Red/Blue running. An emphasis is placed on understandable code over creating a super accurate emulator.

Project Structure

The Cargo workspace feature is used to keep the emulator itself separate from any particular rendering/window management/input handling frontend. All code relating to the emulator itself is found in the core/ directory, while particular usages of that core library are found in other directories (see the list of emulator frontends below).

Emulator Frontends

• wgpu/ - Targets desktop platforms (Linux, Mac, Windows) and the browser (WASM + WebGPU) via pixels.
• terminal/ - Execute the emulator inside a terminal with the Game Boy display expressed with a grid of Unicode characters.
• gbdoctor/ - Run the emulator without a display and the CPU state logged in the format expected by the Game Boy Doctor tool. This frontend exists for development and testing purposes.

Roadmap

• CPU
  • Registers and flags
  • Implement instructions
  • Interrupt handling
  • Pass all Blargg test ROMs
  • STOP instruction
• Memory map
• Timer
• Cartridges
  • No MBC
  • MBC-1
  • MBC-5
• Joypad input
• Graphics
  • Draw background
  • Background scolling
  • Draw window
  • Draw sprites
  • Handle flipped sprites
  • Handle 8x16 sprites
  • Correct ordering of sprite and background tiles
• Frontends
  • Desktop
  • Web
  • Terminal
• Refactoring
  • Remove unnecessary dependencies
  • Simplify cartridge/MBC API
  • Make internal emulator state (e.g., CPU registers) publicly accessible
  • Remove GB Doctor part of public API
  • Tidy up and better document GPU code
  • Simplify cycle counting

Working Games

• Tetris
• Dr. Mario
• The Legend of Zelda: Link's Awakening
• Kirby's Dream Land
• Super Mario Land
• Pokemon Red/Blue