GGBE

Generic Game Boy Emulator, abbreviated as GGBE, is a cycle accurate Game Boy emulator which strives to not compromise code quality and readability for the sake of performance. This is a hobby project written as a learning opportunity to balance readability and performance.

In its current state, the emulator can run DMG games and some CGB games,i.e. it functions as a DMG emulator and a partial CGB emulator at the moment.

Working Games

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Running GGBE

Requirements:

• A compiler which can compile C++17
• SDL2 development libraries
• CMake should be installed

Move to src directory using

cd src

The GGBE executable can be generated by running the following commands in terminal

chmod u+x run.sh
./run.sh

This should generate the build directory.

The emulator can then be launched by the following command

 ./build/GGBE <absolute-path-to-rom>/<relative-path-from-root>

For example if tetris.gb were in roms directory, the command

 ./build/GGBE roms/tetris.gb

should start up tetris.

The boot rom is taken from https://github.com/Hacktix/Bootix.

Key Mapping

Game Boy	Key
Dpad	Arrow Keys
A	Z
B	X
Select	A
Start	S

Project Structure

The Emulator is planned to be divided into 4 major components as of now:

• CPU : Deals with everything related to instructions and interrupts.
• GPU/PPU : Deals with everything related to getting pixels onto the screen
• APU (work in progress) : Deals with everything related to Audio generation and Mixing
• MMU : Takes care of Memory Mapping and Bank Switching

These components are represented as classes and are consolidated as member objects of a class Console, which represents the Console itself. This modular approach makes it easy to write and test code.

Test Suite

Blargg's tests

Test	GGBE
cpu instrs	👍
dmg sound	❌
instr timing	👍
mem timing	👍
mem timing 2	👍

Mooneye's tests

Timer

Test	GGBE
div_write	👍
rapid_toggle	👍
tim00 div trigger	👍
tim00	👍
tim01 div trigger	👍
tim01	👍
tim10 div trigger	👍
tim10	👍
tim01 div trigger	👍
tim01	👍
tim11 div trigger	👍
tim11	👍
tima_reload	👍
tima_write_reloading	👍
tma_write_reloading	👍

MBC

MBC1

Test	GGBE
bits bank1	👍
bits bank2	👍
bits mode	👍
bits ramg	👍
rom 512kb	👍
rom 1Mb	👍
rom 2Mb	👍
rom 4Mb	👍
rom 8Mb	👍
rom 16Mb	👍
ram 64kb	👍
ram 256kb	👍
multicart rom 8Mb	❌

MBC2

Test	GGBE
bits ramg	👍
bits romb	👍
bits unused	👍
rom 512kb	👍
rom 1Mb	👍
rom 2Mb	👍
ram	👍

MBC5

Test	GGBE
rom 512kb	👍
rom 1Mb	👍
rom 2Mb	👍
rom 4Mb	👍
rom 8Mb	👍
rom 16Mb	👍
rom 32Mb	👍
rom 64Mb	👍