This is an implementation of the GameCube controller commmunication protocol for the Raspberry Pi Pico using the PIO.
You should integrate the files manually in your project. The CMakeList.txt is an excerpt corresponding to what you'll need to add to yours.
Check src/joybus.cpp for more information.
This was extracted from https://github.com/JulienBernard3383279/pico-rectangle for public use and is licensed under GPL.
Contact me if you want to use it in a non-GPL project. Discord: Arte#9281, Twitter: https://twitter.com/SSBM_Arte