Delay-Optimal Technology Mapping for Hard-Wired Non-Homogeneous FPGAs

Hsien-Ho CHUANG  Jing-Yang JOU  C. Bernard SHUNG  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E83-A   No.12   pp.2545-2551
Publication Date: 2000/12/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
Category: Performance Optimization
technology mapping,  FPGA,  hard-wired,  non-homogeneous,  XC4000,  

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A delay-optimal technology mapping algorithm is developed on a general model of FPGA with hard-wired non-homogeneous logic block architectures which is composed of different sizes of look-up tables (LUTs) hard-wired together. This architecture has the advantages of short delay of hard-wired connections and area-efficiency of non-homogeneous structure. The Xilinx XC4000 is one commercial example, where two 4-LUTs are hard-wired to one 3-LUT. In this paper, we present a two-dimensional labeling approach and a level-2 node cut algorithm to handle the hard-wired feature. The experimental results show that our algorithm generates favorable results for Xilinx XC4000 CLBs. Over a set of MCNC benchmarks, our algorithm produces results with 17% fewer CLB depth than that of FlowMap in similar CPU time on average, and with 4% fewer CLB depth than that of PDDMAP on average while PDDMAP needs 15 times more CPU time.