Routability crossing distribution and floating pin assignment for T-type junction region

Based on non-crossing relations, vertical constraint relations and net-geom etry relations in one T-type junction region, two kinds of routability cros sing distributions are proposed to improve routing performance in one T-typ e junction region. For routability crossing distribution in one T-type junc tion region, a routability-ordering graph is built to decide a net ordering in O(n(2)) time. For routability quota crossing distribution in one T-type junction region, if the number of net crossings in base channel is more th an a given quota, this net ordering in routability crossing distribution wi ll be further adjusted to satisfy the quota requirement by using a net inte rchange operation in O(n) time. For floating pin;assignment in one;T-type j unction region, global nets are assigned on the boundary between top channe l and base channel by interleaving vacant pins in O(n) time according to a net ordering in routability crossing distribution.