Image Number 4 for United States Patent #5157388.
Special purpose graphics instructions are provided to implement linear interpolation of pixel attributes such as a distance (Z) value or color intensity. Multiple fixed-point real number additions are performed in parallel in a 64-bit adder. The real number sums are truncated upon being loaded in a MERGE register, the contents of which are then shifted. By performing two or more of such instructions consecutively, multiple interpolated values are accumulated in the MERGE register.