A method and apparatus for detecting bits set in a data structure. A first level encoding stage receives bits for the data structure, groups the bits into a set of bit groups, and encodes the set of bit groups to form a set of output bits. A set of intermediate level encoding stages is connected to the first level encoding stage. Each level intermediate encoding stage receives output bits from a previous stage, groups the output bits into a plurality of bit groups, and encodes the plurality of bit groups to generate a plurality of output bits. A final level encoding stage is connected to a last intermediate level encoding stage within the set of intermediate level encoding stages, wherein the final level encoding receives final output bits from a last intermediate level encoding stage within the plurality of intermediate level encoding stages and encodes the final output bits to generate an indication of bits set in the data structure.