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VLSI Design
Volume 2 (1994), Issue 1, Pages 17-32

Register-Transfer Synthesis of Pipelined Data Paths

Department of Electrical & Computer Engineering, University of California, Irvine 92717, CA, USA

Received 21 March 1990; Revised 11 August 1992

Copyright © 1994 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We present a new approach to the problem of register-transfer level design optimization of pipelined data paths. The output of high level synthesis procedures, such as Sehwa, consists of a schedule of operations into time steps, and a fixed set of hardware operators. In order to obtain a register-transfer level design, we must assign operations to specific operators, values to registers, and finish the interconnections. We first perform module assignment with the goal of minimizing the interconnect requirements between RT-level components as a preprocessing procedure to the RT-level design. This will result in a smaller netlist which makes the design more compact and the design process more efficient. In addition to reducing the total number of interconnects, this approach will also reduce the total number of multiplexors in the design by eliminating unnecessary multiplexing at the inputs of shared modules. The interconnect sharing task is modeled as a constrained clique partitioning problem. We developed a fast and efficient polynomial time heuristic procedure to solve this problem. This procedure is 30–50 times faster than other existing heuristics while still producing better results for our purposes. Using this procedure, we can produce near optimal interconnect sharing schemes in a few seconds for most practical size pipelined designs. This efficient approach will enable designers to explore a larger portion of the design space and trade off various design parameters effectively.