Radix-2 Multioperand and Multiformat Streaming Online Addition

In this paper, we present multioperand radix-2 online addition using different data representations (signed-digit, two´s complement, and carry-save), in particular cases in which operands with different representations are added. We use the previously defined online full adder (olFA) as a component to build different multioperand online architectures. To merge data with different representations, an inner conversion of data is performed, eliminating any conversion stage and penalty time. We propose a technique to build multioperand trees efficiently and give six practical rules to deal with different kinds of data in the same adder. For addition of a stream of data, we determine the minimum number of separation cycles required to isolate two successive computations and propose a novel hardware technique that eliminates completely the separation cycles, resulting in the maximum throughput possible.