脳(のう)腐(ふ)

DMG-01 emulator written in modern C++ using Win32 API and SDL2. It is intended as a hobby project to sharpen my C++ skills. The emulator is not complete, so it might have some issues. Please don't hesitate to open an issue if you find any.

Some Screenshots

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Features

• Able to emulate many of the common games with reasonable speed and accuracy.
• Configurable with config.ini (see the below section for more information).
• Accurate CPU emulation (passes Blargg's CPU tests).
• Adequate PPU emulation (passes dmg-acid2 test). This emulator uses Pixel FIFO, as opposed to common scanline renderer.
• Supported cartridge types: Plain ROM, MBC1, MBC1+RAM, and MBC1+RAM+BATTERY. MBC1 RAM savestates are supported.
• Ability to preview the background map up to three tiles.
• Allows custom colour palettes.
• Ability to take screenshots to .bmp files.

config.ini Explained

When you run the emulator for the first time, the config.ini with default settings will be created. The example contents of the file is shown below

BootROMPath=C:\Users\Jimmy\OneDrive\Documents\git\noufu\ROMS\Boot\dmg_boot.bin
CPULogging=0
Color0=C4.F0.C2
Color1=5A.B9.A8
Color2=1E.60.6E
Color3=2D.1B.00
InterruptLogging=0
MMULogging=0
PreviewBackground=1
ScreenScaleFactor=2
UseBootROM=1

• UseBootROM - Set to 1 if you want to run the boot ROM at startup.

• BootROMPath - A path to the DMG boot ROM. This field is required if you set UseBootROM to 1.

• Color0, Color1, Color2, Color3 - Colour palette to be used by PPU. Its values follow this format: RED.GREEN.BLUE. RED, GREEN, and BLUE must be written as 2-digit hexadecimal values. See Colour Palettes section for examples.

• ScreenScaleFactor - Sets the display size. If it is set to 1 then the resolution will be 160x144. If 2 then it will be 320x288, etc.

• CPULogging - If you want the emulator to log its CPU state (currently buggy and will make the emulation slower, so I don't recommend turning it on for now...).

• InterruptLogging - Log the state of interrupt manager if turned on (1).

• MMULogging - Log the state of MMU if turned on.

• PreviewBackground - Turn on if you want to preview the background map. The below is the demonstration of this feature.

mario-bg-preview.mp4

The status bar is flickering because I miscalculated when the VBlank period should end. It's already fixed, so don't worry about that. I will create the new demo video when I have time.

Keybindings

• A - 'A' button
• S - 'B' button
• Enter - 'start' button
• Space - 'select' button
• ← - DPad left
• ↑ - DPad up
• → - DPad right
• ↓ - DPad down

Build Instructions

Requirements:

• TDM-GCC v9.2.0 (x64)
• fmt v8.0.0 (already preinstalled in include/3rdparty)
• SDL v2.0.12 (optional)

Run setup.bat first before anything else.

To build, type

mingw32-make SDL=1

Remove SDL=1 if you don't have SDL installed.

To clean, type

mingw32-make clean

Releases

Currently there are 3 different builds for this emulator.

• cli\ - Rudimentary CLI debugger.
• gui\gdi - GUI with Windows GDI32 graphics output.
• gui\sdl - GUI with SDL2 graphics output.

You can fetch yours here.

Colour Palettes

Colours can be modified in config.ini.

GameBoy Green (default)

Color0=E0.F8.D0
Color1=88.C0.70
Color2=34.68.56
Color3=08.18.20

Greyscale

Color0=FF.FF.FF
Color1=A9.A9.A9
Color2=54.54.54
Color3=00.00.00

SpazeHaze

Color0=F8.E3.C4
Color1=CC.34.95
Color2=6B.1F.B1
Color3=0B.06.30

Mist GB

Color0=C4.F0.C2
Color1=5A.B9.A8
Color2=1E.60.6E
Color3=2D.1B.00

Acknowledgements

This project wouldn't be possible if it weren't for infamous pandocs and the awesome emudev community, especially its Discord server. I get a lot of my questions answered there. Also, I owe a lot to Optix's GBEDG. It helped me to understand and implement PPU's pixel FIFO rendering algorithm.