I had to do it to implement a 16-instruction loop for the TI RM4's High-End Timers, which are programmable timers that you can offload arbitrary pulse-train generation to, among other things.

http://www.ti.com/general/docs/litabsmultiplefilelist.tsp?li...

Every instruction was a state and I had to model each of the transitions between instructions to understand the program flow.