US Patent 7720900 Fused multiply add split for multiple precision arithmetic

An apparatus and method for performing floating-point operations, particularly a fused multiply add operation. The apparatus includes a arithmetic logic unit adapted to produce both a high-order part (H) and a low-order part (L) of an intermediate extended result according to H, L=A*B+C, where A, B are input operands and C an addend. Each H, L part is formatted the same as the format of the input operands, and alignment of the resulting fractions is not affected by alignment of the inputs. The apparatus includes an architecture for suppressing left-alignment of the intermediate extended result, such that input operands for a subsequent A*B+C operation remain right-aligned.