Design Methods for Polymorphic Combinational Logic Circuits based on the Bi_Decomposition Approach

Polymorphic circuits are a special kind of digital logic components, which possess multiple build-in functions. In different environments, a polymorphic circuit would perform different functions. Evolutionary Algorithms, Binary Decision Diagrams (BDD) and the multiplex method have been adopted to design polymorphic circuits. However, the evolutionary methods face the scalable problem. The BDD method consumes too much gate resource. The polymorphic circuit built by the multiplex method rarely contains polymorphic gates. In this paper, based on the traditional Bi_Decomposition circuit design approach, two methods, i.e. the Poly_Bi_Decomposition method and the Transformation&Bi_Decomposition method, are proposed for designing polymorphic circuits. The Poly_Bi_Decomposition method can design relatively large and gate-efficient polymorphic circuits with a higher percentage of polymorphic gates. The Transformation&Bi_Decomposition method can use the traditional circuit design approaches and tools, e.g. Bi_Decomposition, to design polymorphic circuits directly. The experimental results show the good performance of the proposed methods.