Crossbar circuitry for applying a pre-selection prior to arbitration between transmission requests and method of operation of such crossbar circuitry

摘要

Crossbar circuitry has data input and output paths, and at each intersection between a data input and output path, a crossbar cell is provided. A transmission circuit is responsive to a stored routing value to couple a data input path to a selected data output path. Pre-selection circuitry cooperates with the pre-selection circuits of other crossbar cells on the same data output path to use the bit lines of the data output path to compare quality-of-service values associated with multiple asserted transmission requests and to determine a subset thereof which have a highest value of the quality-of-service values. Arbitration circuitry implements a predetermined priority scheme to choose from that subset of requests and to cause the configuration storage circuit of only one crossbar cell associated with the same data output path to have its routing value programmed to the first value, thereby resolving conflict between multiple asserted transmission requests.