A GameBoy emulator written in Cython
I wrote the frontend for it in C++ with SDL2, then wrote bindings for that in Cython, so that I can use threads for the frontend. Supports saving. The main.py file checks whether the frontend.dll is still up to date, or if it has been rebuilt, and copies it over if necessary.
I get framerates of about 3000fps on my machine. I think the biggest performance gain comes from the fact that the entire emulator runs without the GIL (global interpreter lock), and is essentially C++ code, albeit written in a very obfuscated way.
I could have optimized it more, especially the TIMA register, but I got higher framerates than I expected already, so I didn't mind too much. To edit the controls, take a look at src/CyBoy.pyx in the function spawn_frontend. Also supports controllers through SDL2.
It was very fun to figure out what Cython is like, and to know how to link C/C++ to python with it.
To run the emulator, I created a virtual python 3.9 environment, and installed Cython on it. Then run.bat would setup the cython extension, and main.py would import it and run it. To run it yourself, simply install the Cython module, and run the commands similar to those in run.bat. It will generate .cpp and .pyd files (in place) that python can import. main.py will load the ROM you tell it to, and start the emulator.