How do I implement a buffer that saves data on a triger, and then a subsystem that works on this data?

I am working on a project where I have a correlator running, and once the correlation amplitude is above a certain value, I want the model to save a number N of previous data points, then apply a function to them using another subsystem.

I am new to simulink, but I am very familiar with Matlab codes. I am still struggling with sample based way of operation, and I would really appreciate any help in applying this idea, or a resource that I can use to learn about those things.