emuboy's Introduction

Emu Boy

A Nintendo Game Boy emulator written in C++.

Why another emulator?

There are many PC-based emulators that have existed for some time including VBA and BGB. This project was intentionally started independently as a hobby/practice exercise.

Acknowledgments

Emu Boy has been built using Game Boy hardware information available online, primarily:

The repo includes a binary of GBSnake.

Dependencies

Emu Boy uses SFML for outputting video & audio, and Google Test for unit testing.

Current status

As of now Emu Boy is still in its early stages and is very much a work in progress. It currently supports the following:

Fairly cycle-accurate emulation of the LR35902 CPU (all documented instructions + interrupts)
Full graphics implementation (sprites + background + window support)
Runs (at least) the included snake and Super Mario World, though the latter has some graphical glitches
Unit testing of most CPU instructions
Windows-only (Visual Studio 2015 solution)
Simulates the slow response-time of the Game Boy LCD screen and smoothes upsized jagged pixels
Keyboard input

To-do list

Various features remain to be added including:

Sound
Menus & ROM file selector
Linux/Mac OSX support
Performance optimisation

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emuboy's Issues

Implement timer logic

Add sound support

Check CPU emulation conformance

CPU instruction test ROM is available from http://gbdev.gg8.se/files/roms/blargg-gb-tests/

Super Mario Land selects invalid ROM bank

Near the beginning of the 3rd demo Mario level, the CPU sets bit 5 of the ROM bank, which causes indexing beyond the end of the cartridge data (which has only 2 banks).

Could be:

Incorrect value written due to emulator bug
Bits used to select banks not present (i.e. anything above bit 0 in this case) may be ignored, in which case the bank # selected should be the set value mod the # of banks.

Linux support

Add sprite support

Add joypad input via keyboard

w, a, s, d: 4-way direction keys
<, >: B, A buttons
, : Select, start buttons

Pause text garbled in Super Mario Land

When the game is paused (hit when game is running), PAUSE should be displayed in the bottom right of the screen. Currently it shows an unintelligible mess.