INTERNAL EVENT REMOVAL IN HIERARCHICAL AND CONCURRENT STATE DIAGRAMS

This paper starts presenting a brief description of a hardware-software co-design of embedded systems methodology, where statecharts are used for system's behavioral description. Statechart models are a kind of Hierarchical and Concurrent State Diagrams, and the methodology relies on the transformation of the system model into a set of parallel components, which can be seen as a well-structured concurrent state diagram. Major transformations include ill-structured arc transformation, internal event removal and the lifting of hierarchical constructs. The main goal of the paper is to present the algorithms associated with internal event removal, which is one preliminary step within the statechart transformation procedures. The statechart model is edited using a UML-2.0 compliant graphical editor and the developed tool was coded using Ruby and produces XML files, amenable to feed automatic code generation tools (also under development).