Integrating State Charts in Specware and Aspects of Correct Oberon Code Generation

State charts are nite state machines with hierarchical structuring and several models of communication. They are widely used in hardware, software, and communication industries to specify reactive and concurrent systems. In absence of a common semantics for state charts, we use Evolving Algebras, that showed to be powerful enough to model all types of sequential, parallel, distributed and real-time applications of dynamic systems. The generality of evolving algebras allows to mimic all state chart dialects. We use a many-sorted higher-order logic algebraic speci cation language with loose semantics to describe the states of evolving algebras. We have found that the hierarchical structuring operations of state charts coincide with the basic composition operations of the used speci cation language SLANG. We do not have to provide the complicated communication mechanisms existing in many state chart dialects, since SLANG is powerful enough to specify them upon need. SLANG supports constructions for re nement, that can be \misused" to express the transitions of the state charts. After we have embedded a state chart speci cation in SLANG, we can develop formally a correct and e cient implementation from it. This allows the use of state chart methodologies to develop software for safety-critical systems. In order to make the approach usable we will base our work on Specware, a support system for SLANG-speci cations under development at Kestrel Institute. The Specware framework will allow for correctness maintaining optimization using the capabilities of the Kids system, which the Kestrel Institute is currently integrating in Specware. To extend the code generation capabilities of Specware to transition systems we implement the transitions as destructive assignments. We use the programming language Oberon as the back-end. The Evolving Algebras semantics for both Oberon and the transitions facilitates the correctness proof of the code generation.