router.py 文件源码

def score_routing(self, routing, usage_matrix):
        """
        For the given layout, and the routing, produce the score of the
        routing.

        The score is composed of its constituent nets' scores, and the
        score of each net is based on the number of violations it has,
        the number of vias and pins and the ratio of its actual length
        and the lower bound on its length.

        layout is the 3D matrix produced by the placer.
        """
        alpha = 3
        beta = 0.1
        gamma = 1

        net_scores = {}
        net_num_violations = {}

        # Score each net segment in the entire net
        for net_name, d in routing.iteritems():
            net_scores[net_name] = []
            net_num_violations[net_name] = []

            for i, segment in enumerate(d["segments"]):
                routed_net = segment["net"]

                # Violations
                violation_matrix = segment["violation"]
                violations = self.compute_net_violations(violation_matrix, usage_matrix)
                net_num_violations[net_name].append(violations)

                # Number of vias and pins
                vias = 0
                num_pins = 2
                pins_vias = vias - num_pins

                # Lower length bound
                coord_a = segment["pins"][0]["route_coord"]
                coord_b = segment["pins"][1]["route_coord"]
                lower_length_bound = max(1, cityblock(coord_a, coord_b))
                length_ratio = len(routed_net) / lower_length_bound

                score = (alpha * violations) + (beta * pins_vias) + (gamma * length_ratio)

                net_scores[net_name].append(score)

        # print(routing)
        # print(net_scores)
        return net_scores, net_num_violations