04491 – The Kiel Esterel Processor The Kiel Esterel Processor – A Semi-Custom, Configurable Reactive Processor — Dagstuhl Seminar —

Abstract. The synchronous language Esterel is an established language for developing reactive systems. It gives an abstract, well-defined and ex-ecutable description of the application, and can be synthesized into hard-ware and software. Typically, an Esterel program is first translated into other, lower-level languages (such as VHDL or C), and then compiled further. However, there is also the alternative of executing Esterel-like instructions directly. For example, in the REFLIX and RePIC projects, Roop et al. have augmented traditional processors with custom hard-ware to execute Esterel instructions. This patch strategy is a convenient approach, but has some shortages. We present the Kiel Esterel Processor (KEP), a semi-custom, config-urable reactive processor for the direct execution of Esterel programs. It consists of a reactive core and scalable peripheral elements. KEP sup-ports standard Esterel statements directly, except (so far) for the con-currency operator. Valued signals and counter functions in Esterel state-ments are supported by KEP. Due to its control path and its cooperation with elements, KEP obeys exact Esterel (preemption and priority) rules, including for example abort/weak abort (nests)