Multithreaded Reactive Programming—the Kiel Esterel Processor

The Kiel Esterel Processor (KEP) is a multithreaded reactive processor designed for the execution of programs written in the synchronous language Esterel. Design goals were timing predictability, minimal resource usage, and compliance to full Esterel V5. The KEP directly supports Esterel´s reactive control flow operators, notably concurrency and various types of preemption, through dedicated control units. Esterel allows arbitrary combinations and nesting of these operators, which poses particular implementation challenges that are addressed here. Other notable features of the KEP are a refined instruction set architecture, which allows us to trade-off generality against resource usage, and a Tick Manager that minimizes reaction time jitter and can detect timing over-runs.