Programmable optimized-distribution logic allocator for a high-density complex pld

Abstract

A programmable optimized-distribution logic allocator enhances the speed, silicon utilization, logic efficiency, logic utilization, and scalability of very high-density CPLDs including the logic allocator. The programmable optimized-distribution logic allocator provides an optimized number of product terms to each I/O pin of the CPLDS and the same uniform number of product terms as feedback. However, no product terms are permanently connected to either a particular macrocell or a particular I/O pin. The programmable optimized-distribution logic allocator includes a multiplicity of router elements where each router element steers a sum of a selected number of sum-of-product terms from a PAL structure, i.e, a selected number of logic product-term clusters, to a programmably selected logic macrocell. Specifically, the programmable optimized-distribution logic allocator has a plurality of input lines, a plurality of output lines and a plurality of programmable router elements. Each programmable router element has an input terminal connected an input line in the plurality of input lines and an output terminal connected to an output line in the plurality of output lines.