An efficient cut-based algorithm on minimizing the number of L-shaped channels for safe routing ordering

In this paper, based on the assumptions of the geometrical topology in a floorplan graph and the precedence relations in a channel precedence graph, the cuts are further classified into S-cuts, redundant L-cuts, balanced L-cuts, non-minimal L-cuts, non-critical L-cuts and critical L-cuts. An efficient cut-based algorithm on minimizing the number of L-shaped channels is proposed. The time complexity of the algorithm is proved to be in O(n) time, where n is the number of line segments in a floorplan graph. Finally, several examples have been tested on Dai's and Cai's algorithms and the proposed algorithm. The experimental results show that the proposed algorithm defines fewer L-shaped channels than Dai's and Cai's algorithms in the definition of straight and L-shaped channels for the assignment of safe routing ordering.