jgb

Note: This emulator has been largely obsoleted by the Game Boy core in my multi-system emulator, but this emulator does still support two features that one does not:

• MBC7 cartridges (Kirby Tilt 'n' Tumble)
• MBC5 rumble support (e.g. Pokemon Pinball)

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An attempt at writing a Game Boy emulator.

jgb is a cross-platform low-level Game Boy [Color] emulator with no game-specific logic or game-specific hacks. It is not completely cycle-accurate due to CPU emulation being instruction-based rather than cycle-based, but it should be able to run the vast majority of licensed Game Boy and Game Boy Color games.

Features:

• Game Boy and Game Boy Color emulation
• Support for cartridges using MBC1, MBC2, MBC3, MBC5, MBC7 mappers
• Save file / cartridge RAM persistence to disk
• Keyboard input and DirectInput gamepad support
• Support for the MBC3 real-time clock with persistence to disk
• Support for MBC5 rumble cartridges (requires a gamepad with rumble)
• Support for the MBC7 accelerometer (requires a gamepad with an accelerometer)
• 2x fast-forward toggle
• Save & load state
• Three different color palette options for GB mode (black & white, light green tint, intense lime green)
• Option for GBC color correction to more closely mimic how games looked on the Game Boy Color LCD
• Option for integer scaling regardless of window/display size

Not Currently Implemented:

• Serial port and GBC IR functionality
• Use of GBC palettes in games that don't support GBC enhancements
• Cycle-based interrupt handling to make Pinball Deluxe not crash after a few seconds of gameplay
• Various less commonly used mappers
  • MBC6 (only used in 1 game, Net de Get: Minigame @ 100)
  • Multi-game mappers such as MBC1M and MMM01 (only used in compilation cartridges)
  • Custom third-party mappers such as HuC-1, HuC-3, TAMA5, Wisdom Tree (used in unlicensed games and a small number of Japanese games)

Requirements

Rust

This project requires the latest stable version of the Rust toolchain to build. See link for installation instructions.

SDL2

This project requires SDL2 core headers and TTF headers to build.

Linux (Debian-based):

sudo apt install libsdl2-dev libsdl2-ttf-dev

Windows:

• https://github.com/libsdl-org/SDL/releases/
• https://github.com/libsdl-org/SDL_ttf/releases/

GTK3 (Linux GUI only)

On Linux only, the GUI requires GTK3 headers to build.

Linux (Debian-based):

sudo apt install libgtk-3-dev

Build & Run GUI

To build and run the GUI:

cargo run --release --bin jgb-gui

By default the GUI app will read and save its config using the file jgb-config.toml in the current working directory. To override this and use a custom path, use the --config command-line arg:

cargo run --release --bin jgb-gui -- --config /path/to/my/config.toml

Build & Run CLI

To build the CLI and run on a ROM file with audio enabled:

cargo run --release --bin jgb-cli -- -a -f <gb_file>

To view all command-line options:

cargo run --release --bin jgb-cli -- -h

Screenshots