An algorithm for integrated pin assignment and buffer planning

The buffer block methodology has become increasingly popular as more and more buffers are needed in deep-submicron design, and it leads to many challenging problems in physical design. In this article, we present a polynomial-time exact algorithm for integrated pin assignment and buffer planning for all two-pin nets from one macro block (source block) to all other blocks of a given buffer block plan, while minimizing the total cost α · W + β · R for any positive α and β where W is the total wirelength, and R is the number of buffers. By applying this algorithm iteratively (each time, pick one block as the source block), it provides a polynomial-time algorithm for pin assignment and buffer planning for nets among multiple macro blocks. Experimental results demonstrate its efficiency and effectiveness.