Logic Synthesis Through Local Transformations

A logic designer today faces a growing number of design requirements and technology restrictions, brought about by increases in circuit density and processor complexity. At the same time, the cost of engineering changes has made the correctness of chip implementations more important, and minimization of circuit count less so. These factors underscore the need for increased automation of logic design. This paper describes an experimental system for synthesizing synchronous combinational logic. It allows a designer to start with a naive implementation produced automatically from a functional specification, evaluate it with respect to these many factors, and incrementally improve this implementation by applying local transformations until it is acceptable for manufacture. The use of simple local transformations in this system ensures correct implementations, isolates technology-specific data, and will allow the total process to be applied to larger, VLSI designs. The system has been used to synthesize masterslice chip implementations from functional specifications, and to remap implemented masterslice chips from one technology to another while preserving their functional behavior.