ezillinger / ezgb

Gameboy Emulator in C++20

ezgb

This is a Gameboy emulator written from scratch in C++20. It's not super accurate but it is mostly feature complete. It runs on all major desktop platforms as well as in the browser via WebAssembly

Click here to try me in your browser!

Features

• Plays most simple commercial games - ROM Only and MBC1 cartridge types
• Runs in the browser via WebAssembly
• Audio
• Debugger/Disassembler with breakpoints
• PPU Vram Debug Display

Things that can be improved

• Support for more cartridge types, save files
• Interrupt timing accuracy - games that rely heavily on this often stutter
• V-Sync with host sytem without adding an extra frame of latency
• More robust audio system - if the emulator doesn't run full speed you'll get crackling audio
• T-Cycle PPU accuracy
• APU accuracy - currently the oscillators are only updated on trigger
• Performance - the PPU is especially wasteful. A simple tile cache could save a lot of CPU cycles
• Mobile WebAssembly:
  • multi-touch support
  • proper browser detection - currently browser aspect ratio is used
  • mobile friendly menus
  • audio is crackly unless you have a very high end phone

3rd Party Dependencies

I tried to use as few 3rd party libraries as possible The only 3rd party libraries are:

• SDL2
• OpenGL
• ImGui (included)

Building

• Requires CMake, a C++20 compiler, and SDL2
• Tested on GCC, LLVM Clang, MSVC, and Emscripten
• On Linux/MacOS install SDL2 with your package manager
• You'll need to install GCC or LLVM Clang on MacOS - AppleClang doesn't have enough C++20 support
• On Windows download an SDL2 release and set the path in the top level CmakeLists.txt

Controls

• Z - A

• X - B

• A - Start

• S - Select

• Arrow Keys - D-Pad

• Space - Pause Emulation

• N, when paused - Step forward one clock cycle

• M, when paused - Step forward one instruction

Mobile Browser Version

• If your browser has a tall enough aspect ratio ezgb will switch to a mobile layout