A methodology and algorithms for the design of hard real-time multitasking ASICs

Abstract

Traditional high-level synthesis concentrates on the implementation of a single task (e.g. filter, linear controller, A/D converter). However, many applications—multifunctional embedded controllers intelligent wireless end-points, and DSP and multimedia servers—are defined as sets of several computational tasks. This paper describes new techniques for the synthesis of ASIC implementations that realize multiple computational processes under hard real-time constraints. Our synthesis methodology establishes connections between two important comengineering domains: operating systems and behavioral synthesis. Our hierarchical approach starts from an incompletely-specified preliminary solution and uses, interchangeably, operating system and behavioral synthesis techniques to derive increasingly more detailed and accurate design solutions. We have experimented with both optimal and heuristic algorithms to implement this methodology. The optimal algorithm uses several heuristics to speed up the average run time of an exhaustive branch-and-bound search. Force-directed optimization is the core of the heuristic synthesis method. Analysis of the proposed algorithms and the experiments shows that matching the number of bits and type of operational in taskes assigned to the same application-specific processor was the most important factor in obtaining area-efficient designs.