A functional unit in a digital system is provided with a rounding
Multiplication instruction, wherein a most significant product of first
pair of elements is combined with a least significant product of a second
pair of elements, the combined product is rounded, and the final result
is stored in a destination. Rounding is performed by adding a rounding
value to form an intermediate result, and then shifting the intermediate
result right. A combined result is rounded to a fixed length shorter than
the combined product.