Formal system design based on the synchrony hypothesis, functional models, and skeletons

Abstract

Formal approaches to HW and system design have not been generally adopted because designers often view the modelling concepts in these approaches as unsuitable for their problems. Moreover they are frequently on a too high abstraction level to allow for efficient synthesis with today's techniques. We address this problem with a modelling method, which is strictly formal and based on formal semantics, a pure functional language, and the synchrony hypothesis. But the use of skeletons in conjunction with a proper computational model allows to associate a direct hardware interpretation. In particular we use the synchrony hypothesis and a timed signal model to provide a high abstraction for communication at the system level. This facilitates efficient modelling and design space exploration at the functional level, because the designer is not concerned with complex communication mechanisms, and functionality can easily be moved from one block to another. To bridge the gap between an elegant and abstract functional model and the details of an implementation we use skeletons to encapsulate primitive structures, such as FSMs, buffers, computation units, etc. in a purely functional way.