Area-efficient special function unit for mobile vertex processors

An area-efficient special function unit (SFU) for the evaluation of transcendental functions in mobile vertex processors is presented. In spite of infrequent usage, previous implementation of an SFU occupied significant portion of a shader datapath unit. The proposed SFU reduces the area by 54% by performing quadratic interpolation included in the function evaluation with a shared 4D dot product unit and implementing setup circuitry and a lookup table by dedicated hardware for the SFU. By benchmarking shader programs, the performance/area of a shader datapath unit turns out to be improved by 69%.