Methods and apparatus for resource sharing in a programmable interrupt controller

Abstract

Efficient techniques are described for identifying active interrupt requests to improve performance and reduce power requirements in a processor system. A method to identify active sampled interrupt requests begins with scanning groups of the sampled interrupt requests one group at a time to identify an active interrupt request in any scanned group. A group of interrupt requests is an M/R priority of N sampled interrupt requests, M is the number of priority levels, and R is a resource sharing factor. A group selection circuit is updated to a new group in response to having identified an active interrupt request to improve the latency in processing high priority interrupt requests. Also, groups having active interrupt requests may be identified by early detection or look ahead circuitry. The scanning of groups of interrupt requests may be stopped until the next interrupt request sample point has been reached to reduce power utilization.