General area router based on planning techniques

A general area router (GEAR) based on the planning approach is proposed and implemented. Two meta-planning techniques, graceful retreat and least impact, are used to manage the selection of net segments and the assignment of track resources. Apart from the novel application of these planning techniques, we have also consolidated many effective routing heuristics into GEAR so that it is able to solve a variety of difficult routing problems. These include channel routing, switchbox routing, staircase routing, rectilinear area routing with obstacles, and other general area routing problems. Extensive simulation results indicate that GEAR is very competitive compared with the best known special-purpose routers