Showing papers by "Yao-Wen Chang published in 1995"

FPGA global routing based on a new congestion metric

Abstract: Unlike traditional ASIC routing, the feasibility of routing in FPGAs is constrained not only by the available space within a routing region, but also by the routing capacity of a switch block. Recent work has established the switch-block capacity as a superior congestion-control metric for FPGA global routing. However, the work has two deficiencies: (1) its algorithm for computing the switch-block capacity is not efficient, and (2) it, as well as the other recent works only modeled one type of routing segments-single-length lines. To remedy the deficiencies, we present in this paper efficient algorithms for obtaining the switch-block capacity and a graph modeling for routing on the new generation FPGAs with a versatile set of segment lengths. Experiments show that our algorithms dramatically reduce the run times for obtaining the switch-block capacities. Experiments with a global router based on the switch-block and channel densities for congestion control show a significant improvement in the area performance, compared with one based on the traditional congestion metric.

Design and analysis of FPGA/FPIC switch modules

Abstract: Switch modules are the most important component of the routing resources in FPGAs and FPICs. The quality of switch modules greatly affects FPGA/FPIC routing solutions. The switch-module design problem was studied by K. Zhu et al. (1993). In order to analyze the routability of designed switch modules, a heuristic algorithm based on network-flow techniques was proposed. In this paper, we mathematically show that the network-flow based algorithm has provably good performance with the bounds 5 and 5/4 away from the optima for two types of switch modules, respectively. Based on the analyses, we developed a new method for designing switch modules. Experimental results show that our designed switch modules significantly improve routability, compared with those by K. Zhu et al. Extensive experiments also show that the network-flow based algorithm is highly accurate and runs very efficiently.