Based on non-crossing relations, vertical constraint relations and net-geometry relations
in one T-type junction region, two kinds of routability crossing distributions are
proposed to improve routing performance in one T-type junction region. For routability
crossing distribution in one T-type junction region, a routability-ordering graph is built
to decide a net ordering in O(n2) time. For routability quota crossing distribution in one
T-type junction region, if the number of net crossings in base channel is more than a
given quota, this net ordering in routability crossing distribution will be further adjusted
to satisfy the quota requirement by using a net interchange operation in O(n) time. For
floating pin assignment in one T-type junction region, global nets are assigned on the
boundary between top channel and base channel by interleaving vacant pins in O(n)
time according to a net ordering in routability crossing distribution.
