SL2SF: Refactoring Simulink to Stateflow

In the Matlab Simulink environment, systems can be modelled using Simulink block diagrams and Stateflow state charts. While stateful logic is more naturally modelled using Stateflow, in practice complex block diagrams are often used instead, resulting in models that are hard to understand and maintain. In order to improve the maintainability and understandability of large industrial models, this paper presents a strategy for refactoring Simulink block diagrams implementing stateful logic into functionally equivalent Stateflow state charts that more naturally represent the intended behaviour. To bridge the gap between the syntax of block diagrams and state charts, Mealy machines represented by tabular expressions are used as an intermediate representation. The compositional language of block diagrams is used to combine tables modelling individual blocks into a table for the entire block diagram which describes the high level state machine encoded in the Simulink subsystem. A prototype tool that performs the translation from Simulink to Stateflow automatically is discussed.