CASTOR: state assignment in a finite state machine synthesis system

The authors describe some of the state assignment heuristics, which are applied in the finite state machine synthesis system CASTOR. They concentrate on algorithms for two-level logic implementations, while work on algorithms for multi-level logic implementations is in progress. Input to the system is a description of the FSM in form of a state table. CASTOR generates an appropriate controller consisting of pre- and postprocessing structures around a kernel FSM, which may be a PLA, a ROM or random logic. In the case of a PLA or random logical controller coding constraints are extracted for the kernel FSM. Then these coding constraints have to be satisfied by adequate state assignment algorithms in order to minimize the area of the physical implementation