Efficient translation of statecharts to hardware circuits

Abstract

Traditional description techniques like Finite State Machines (FSMs) are inadequate for current day complex hardware control circuits as they are flat and unstructured. Recently Harel [1987] defined statecharts by introducing concurrent and hierarchical structure to FSMs. Statecharts can be implemented in hardware using the conventional implementation scheme of combinational-logic block with a feedback register. The main problem here is the encoding of state configurations. The encoding, besides uniquely identifying configurations should be easily decomposable into the codes of constituent states so that the set of permissible transitions in these states can be performed and the resulting outputs and the next configuration can be computed. This paper proposes a new scheme for encoding statechart configurations. The distinguishing feature of this scheme is to encode not only basic states but also intermediate states. The encoding is based upon the hierarchical and concurrent structure of statecharts. It has been shown both theoretically and experimentally that the scheme performs better than existing encoding schemes.