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VLSI Design
Volume 10, Issue 2, Pages 155-167
http://dx.doi.org/10.1155/1999/12841

Routability Crossing Distribution and Floating Pin Assignment for T-type Junction Region

Computer Systems Research Center, National Chiao Tung University, Taiwan, Hsinchu, China

Received 15 July 1997; Accepted 8 July 1998

Copyright © 1999 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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.