QMDD-based one-pass design of reversible logic: Exploring the available degree of freedom (work-in-progress report)

Research on synthesis of reversible circuits has found substantial consideration in the past. Corresponding methods can be categorized into functional approaches (which often require a prior embedding step) and structural ones (which are often based on mapping). While functional approaches are less scalable and yield circuits with significantly larger costs, structural approaches typically yield circuits where the number of circuit lines is magnitudes above the minimum. Recently, also the idea of a one-pass design flow has been proposed, which aims to overcome the contradictory shortcomings of both approaches by combining the embedding and the synthesis step of the functional design flow. While this yields further opportunities for a more efficient synthesis, the actually available degree of freedom has not fully been explored yet—not to mention fully exploited. In this work-in-progress-report, we are discussing this issue and explore in detail the potential offered by the one-pass design flow. To this end, we consider the implementation of this flow using QMDD-based synthesis as a representative. The conducted investigations provide a more detailed understanding of this recently proposed flow and demonstrate its potential to be exploited in future work.