How can I reset continuous states at a discontinuity in a C-mex S-function

I am trying to create a C-mex S-function with a discontinuity handling of continuous states.

After the discontinuity is detected using the mdlZeroCrossings, I am looking for the proper way to reset the values of some of the continuous states at the event point.

What is the proper way to reset a continuous state depending on the mode at the discontinuity event ?