Priority encoder

Abstract

A circular priority encoder includes a linear priority encoder that receives a plurality of requests of ranks 1 to n on corresponding request lines. The encoder acknowledges on an acknowledgement output the request of the lowest rank among the requests it receives; a mask register is connected to transmit to the linear encoder only the requests whose ranks are determined to be active by the ranks of active bits of a mask contained in the mask register. A mask generator provides the mask register with a mask in which bits of ranks 1 to i (i=1, 2 . . . n) are inactive and the remaining bits are active when a request of rank i is acknowledged by the linear encoder.