Set point production

Hi Dear,
I want to change the mixer of the px4 code for my own drone.
I do not know how the set point is produced.
Does anyone know what the set point production algorithm is?

The input to the mixer is the output of the controllers, which in turn take as inputs estimator etc. You can see the architecture here:

Thanks for replay ,
I do not know the algorithm that make set-point. I mean I need the method of making set-point.