Language and Compiler for Optimizing Datapath Widths of Embedded Systems

Akihiko INOUE  Hiroyuki TOMIYAMA  Takanori OKUMA  Hiroyuki KANBARA  Hiroto YASUURA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E81-A    No.12    pp.2595-2604
Publication Date: 1998/12/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
Category: Co-design
embedded system design,  hardware/software codesign,  retargetable compiler,  

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The datapath width of a core processor has a strong effect on cost, power consumption, and performance of an embedded system integrated with memories into a single-chip. However, it is difficult for designers to appropriately determine the datapath width for each application because of the limited reusability of software and the lack of compilation techniques. The purpose of this paper is to clarify supports required from software for the optimal datapath width determination. As a solution, an embedded programming language, called Valen-C, and a retargetable Valen-C compiler are proposed. In this paper, the syntax and semantics of Valen-C along with the mechanism of the Valen-C retargetable compiler and how to preserve the accuracy of computation of programs in relation to various datapath widths are also described. Experiments with practical applications show that the total cost of the system including a core processor, ROM, and RAM is drastically reduced with little performance loss by reducing the datapath width.