Programming Real-time Autofocus on a Massively Parallel Reconfigurable Architecture using Occam-pi

Recently we proposed occam-pi as a high-level language for programming massively parallel reconfigurable architectures. The design of occam-pi incorporates ideas from CSP and pi-calculus to facilitate expressing parallelism and reconfigurability. The feasability of this approach was illustratedby building three occam-pi implementations of DCT executing on an Ambric. However, because DCT is a simple and well studied algorithm it remained uncertain whether occam-pi would also be effective for programming novel, more complex algorithms. In this paper, we demonstrate the applicability of occam-pi for expressing various degrees of parallelism by implementinga significantly large case-study of focus criterion calculation inan autofocus algorithm on the Ambric architecture. Autofocus is a key component of synthetic aperture radar systems. Two implementations of focus criterion calculation were developedand evaluated on the basis of performance. The comparison of the performance results with a single threaded software implementation of the same algorithm show that the throughput of the two implementations are 11x and 23x higher than the sequential implementation despite a much lower (9x) clock frequency. The two designs are, respectively, 29x and 40x moreenergy efficient.©2011 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.SMEC