1. Field of the Invention
The present invention relates to a computing technology and, more particularly, to a method and apparatus for arithmetic operation on a value represented in a floating-point format.
2. Description of the Related Art
Fixed-point numbers and floating-point numbers are known as methods for dealing with numbers in a computer or a digital signal processor (DSP). A floating-point number requires an operation on fractions. Therefore, the speed of computing a floating-point number tends to be lower than that of computation a fixed-point number in which the base point is fixed at a certain position. Meanwhile, since the base point of a floating-point number can be changed, the floating-point format can represent a number with a small absolute value with high precision and is also capable of representing a number with a large absolute value.
Pixel pipelines in graphics hardware perform lighting computation and image processing. Such computation includes normalization of vectors, computation of inverse matrices and the like. In this process, reciprocals and inverse square roots are computed. Conventionally, a pixel pipeline operates on integers. Thus, computation of reciprocals and inverse square roots is based on an integer table and linear interpolation between integers. However, a growing number of pixel pipelines implemented in recent years support floating-point arithmetic. In this background, there is a demand for high-speed computation of reciprocals and inverse square roots of floating-point numbers. The demand is particularly high in arithmetic operations for realtime graphics. With the trend for increased number of parallel processing pipelines, it is desirable that hardware resources used be minimized in respect of cost.