BRANCH SEARCHING TO PRIORITIZE RECEIVED INTERRUPT

A data processing system 2 for identifying the highest priority source signal from a plurality of signals each controlling the setting of a bit of a status word held within a status register 10 using programmable mask words. The mask words are used in a branch search strategy to successively narrow the possibilities for the highest priority bit at each search level until a single bit within the status word is identified corresponding to the highest priority interrupt signal. The programmable masks may be programmed for a particular configuration of the priorities of the respective bits within the status word. The branch search strategy provides a reduced maximum interrupt latency and improved predictability in the interrupt latency.