Generalized cofactoring for logic function evaluation

Abstract

Logic evaluation of a Boolean function or relation is traditionally done by simulating its gate-level implementation, or creating a branching program using its binary decision diagram (BDD) representation, or using a set of look-up tables. We propose a new approach called generalized cofactoring diagrams, which are a generalization of the above methods. Algorithms are given for finding the optimal cofactoring structure for free-ordered BDD's and generalized cube cofactoring under an average path level (APL) cost criterion. Experiments on multi-valued functions show superior results to previously known methods by an average of 30%. The framework has direct applications in logic simulation, software synthesis for embedded control applications, and functional decomposition in logic synthesis.