Leading one prediction unit for normalizing close path subtraction results within a floating point arithmetic unit

摘要

An optimized multimedia execution unit configured to perform vectored floating point and integer instructions. In one embodiment, the execution unit includes an add/subtract pipeline having far and close data paths. The far data path is configured to handle effective addition operations, as well as effective subtraction operations for operands having an absolute exponent difference greater than one. The close data path, conversely, is configured to handle effective subtraction operations for operands having an absolute exponent difference less than or equal to one. The execution unit may also include a plurality of add/subtract pipelines, allowing vectored add, subtract, and integer/floating point conversion instructions to be performed. The execution unit may also be expanded to handle additional arithmetic instructions (such as reverse subtract and accumulate functions) by appropriate input multiplexing. The execution unit may also be configured with a leading one prediction unit that is configured to predict the position of a leading one value for certain results in order to improve normalization times.