Untangling twisted nets for bus routing

Previous works [1], [2] on PCB bus routing assume matched pin ordering for both sides. But in practice, the pin ordering might be mismatched and the nets become twisted. In this paper, we propose a preprocessing step to untangle such twisted nets. We also present an algorithm to solve this untangling problem. Our algorithm produces an optimal single-detour routing scheme that rematches the pin ordering. By integrating our preprocessing step into the bus router in [2], we show that many routing problems that cannot be solved previously can now be solved with insignificant increase in runtime.