Exploiting Coding Techniques for Logic Synthesis of Reversible Circuits

Reversible circuits are composed of a set of circuit lines that are passed through a cascade of reversible gates. Since the number of circuit lines is crucial, functional logic synthesis approaches have been proposed which realize circuits where the number of circuit lines is minimal. However, since the function to be realized is often non-reversible, additional variables have to be added to the function in order to establish reversibility-leading to a significant overhead that affects the scalability of the synthesis method and yields rather complex circuits. In this work, we propose to overcome these problems by exploiting coding techniques in the logic synthesis of reversible circuits. To this end, we propose an intermediate encoding of the output patterns that requires fewer additional inputs and outputs. Using this synthesis scheme allows to perform the majority of the synthesis on significantly fewer variables and to exploit several dont care values in the code. Experimental evaluations where we obtain better scalability and circuits with magnitudes fewer costs confirmed the benefits of the proposed synthesis approach.