An efficient two-layer irregular-channel router

An efficient two-layer irregular-channel router is presented which is suitable for both regular and irregular channels. The router uses a heuristic approach to determine all of the subnet-weights for a given channel. It constructs the maximum subnet-weight path in order to determine the best set of subnets for each track. For a given irregular channel, the obstacles are treated as subnets with a highest weight, which reduces the irregular channel-routing to a regular channel-routing. Also, user intervention is permitted by the router for generating a minimum wire length for the specified net. In addition, since this router uses restricted doglegging, the likelihood for it to process a cyclic routing channel is reduced. By using an intermediate routing format, the CF router can easily be used in conjunction with the CF mask generator to generate masks. The CFR router is shown to be very effective in generating acceptable results quickly for both regular and irregular channels