Request for informations about the PX4 Auto-pilot

We are currently in engineering school and are working on a project including the PX4 auto-pilot. The purpose of the project is to understand how the PX4 program works(Calibration Accelerometer, Calibration Radiometry,Magnetometer Calibration).

The problem is that we don’t find the source code of these functions.

Moreover, does it work by command used (commande par retour d’état in French) ?

Calibration code is in the commander module