Methods and apparatus provide for accumulating bit streams from four
partial products and producing a carry-save output pair, including:
producing the save, S, portion of the carry-save output pair, in
accordance with the following Boolean expression: S=d3 XOR ((d0 XOR d1)
XOR (d2 XOR Cin)), wherein d0, d1, d2, d3 are the bit streams from the
four partial products, and Cin is a carry in bit stream receivable from
an adjacent compression circuit of an overall partial product reduction
array.