Causality analysis of synchronous programs with delayed actions

Abstract

Synchronous programs are well-suited for the implementation of real-time embedded systems. However, their compilation is difficult due to the paradigm that microsteps are executed in zero time. This can yield cyclic dependencies that must be resolved to generate single-threaded code. State of the art techniques are based on a fixpoint computation at compile time that 'simulates' the microstep execution. However, existing procedures do not consider delayed actions that have been recently introduced in synchronous languages. In this paper, we show that the analysis of programs with delayed actions can be performed by two fixpoint computations, one for the initialization and one for the transitions of the system. Moreover, we discuss an implementation using BDDs that is based on dual rail encoding.