A robust channel router

A new robust channel router, with very simple heuristics, is being introduced. It is able to handle two-layer channels, three-layer channels with two horizontal layers and one vertical layer (HVH), and three-layer channels with two vertical layers and one horizontal layer 0. This router uses the horizontal layers only for horizontal wires, and the vertical layers only for vertical wires. It is robust in the sense that small changes in the input or in the algorithm do not have a major effect on the results, which is a key feature of its ability to support the wide variety of routing models. The presented router achieves extremely good results. For example, it has routed the Deutsch difficult example in 19 tracks (i.e., in its density) with signilicantly less metal than other published results. For the three-layer case, that example was routed in 10 tracks with no stacked vias, which is better than any other three-layer router published so far.