The Simulation of Synchronous Reactive Systems in Ptolemy II

Paul Whitaker

Master's Report, Memorandum UCB/ERL M01/20, Electronics Research Laboratory, University of California, Berkeley, May 2001.



The Synchronous Reactive (SR) domain in Ptolemy II models systems as components with both infinite processing resources and infinite communication bandwidth. Computation within components and data transfer between components are considered to happen instantaneously. Therefore, a given system is simulated as if all of its components execute and produce outputs at the same time. This raises interesting issues, particularly in systems with feedback. To guarantee a deterministic model of computation, outputs are permitted to have undefined value, and certain constraints are imposed on component behavior. Specialized components, such as finite state machines, may execute even when some inputs are undefined, producing only those outputs that can be determined from the defined inputs. This report outlines the semantics of the SR model of computation and describes its implementation as a domain in Ptolemy II.