Hi @Darkus3,
The control allocation matrices (“mixer tables”) are generated by the python script px_generate_mixers.py given the geometries of the vehicles.
After this, the matrix is used here to create the thrust output of each motor with the following expression:
thrust = roll*roll_scale + pitch*pitch_scale + yaw*yaw_scale + collective_thrust*thrust_scale
Where the output scale is used when you have a different prop/motor (tricopter for example).
Then, in the same file are implemented some strategies (called Airmode) to avoid loss of control when some actuators reach saturation.
For more details, check this control allocation repository where the algorithm as been prototyped in Python. This Python script is also used here to verify the C++ implementation.
EDIT: updated comment for v1.9 release