Yet another Gameboy emulator.

Implemented (at least I think so) features:

• Emulation of all CPU instructions
• Memory bus with RAM and redirection of MMIO requests to the peripherals
• MBC1, MBC2, MBC5, external cartridge RAM with save/load (battery emulation)
• Interrupts
• Timer
• Input
• Quite inaccurate, but full PPU implementation: background, window, sprites, OAM DMA
• Architecture - emulation core with abstract interface and frontends: SFML and libretro

The emulator passes Blargg's cpu_instr, instr_timing, mem_timing tests.

Tested software:

• Super Mario Land - looks playable
• Super Mario Land 2 - looks playable
• The Legend of Zelda: Link's Awakening - looks playable
• Kirby's Dream Land - looks playable
• Tetris - looks playable
• Dr. Mario - looks playable
• Bomb Jack - looks playable
• Ant Soldiers - looks playable
• V-Rally - looks playable
• Oh! Demo - looks as intended
• Road Rash - screen flickering during gameplay, but playable
• Kirby's Dream Land 2 - hangs
• Is That A Demo In Your Pocket? - some visual glitches

Building

cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make

Supports both Clang and GCC. SFML backend requires CSFML (sudo apt install libcsfml-dev libsfml-dev in Ubuntu and derivatives).

For Android build:

./android_cmake_gen.sh -DCMAKE_BUILD_TYPE=Release
cd build
make

(You must specify the path to Android NDK in the script)

Running

Binaries are located in build folder

• SFML frontend - run as usual CLI application
• libretro frontend via Retroarch - move gb_libretro.so and gb_libretro.info to corresponding core and core info directories (retroarch/cores in case of Linux)

Retroarch moment - games run too fast if "Threaded Video" option is enabled. Note than it's enabled by default on Android. I haven't figured out the reason yet, it might be a Retroarch bug

Retroarch on Android moment - it's not possible to access the core directory as it's located in private app storage. On the other hand, Android security policies forbid dynamic loading of libraries from shared storage. Retroarch has option of manual core installing - but it ignores core info file and allows only BootROM to be run. However, core info directory can be located in shared storage. So, you must (1) install core using "Install or Restore Core" option, (2) put core info file in some folder in shared storage and (3) select this folder as core info directory.

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