A Cooperative Approach to Switchbox Routing

Switchbox routing is an intractable problem in very large scale integrated-circuit (VLSI) physical design automation. From a computational point of view, the problem is NP-complete. This paper presents a new approach to the switchbox routing problem. The core of this new approach is a novel routing technique, namely synchronized routing, inspired by human routing experts. The synchronized routing is a novel `multiple-nets-at-a-time' routing technique, which can capture constraints dynamically formed between nets during the process of routing, and can use the constraints to minimize conflicts between the nets and therefore reduce the search space. If a wire segment is blocked during the synchronized routing, rip-up routing is utilized to identify and dismantle obstacles of the blocked wire segment. These two routing techniques are complemented by pattern routing, which is used for connecting net terminals in special patterns. These three routing techniques cooperate with each other to achieve high routing speeds and improve routing completion rates. A switchbox router called CSR, based on this cooperative approach, has been implemented. Experimental results show that it is effective and efficient, especially for dense switchbox routing problems