Abstract: An operation circuit for performing a population count. The operation circuit comprises a first circuit being coupled to receive a first data element. A first packed data includes the first data element and a second data element. Each of the data elements has a predetermined number of bits. The first circuit is for generating a first result data element representing a total number of bits set in the first data element. The operation circuit further comprises a second circuit being coupled to receive the second data element. The second circuit is for generating a second result data element representing a total number of bits set in the second data element.

Abstract: An adder for a 64-bit microprocessor which has three modes of operations, specifically, a 64-bit mode, a second mode where the adder in effect is four 16-bit adders and a third mode where the adder is, in effect, eight 8-bit adders. Two levels of Kogge-Stone trees are used, the first to generate group carries and propagate signals and the second for generating the carry signals for the 64-bit case. In the case of the 8-bit and 16-bit modes, the second level Kogge-Stone tree is not used, rather ordinary logic generates the appropriate carries. Exclusive ORing for conditional sums is performed in parallel with the generation of the carry signals.