pinging filters + shift registers + cross feedback loops

Hi everyone, I've been programming in max pretty intensively for a couple years and I'm trying to make sense of this patch:

The user is kind enough to post his work on github. I downloaded the patch to play with it and I still don't quite understand it. Maybe it's because of how the patch is laid out, but I'm still having a hard time wrapping my head around the structure and signal flow. Can anyone shine some light on this for me?