Method and apparatus for providing fast switching between floating point

Abstract

A system and method is provided that adds another floating point register set in the floating point execution unit of a microprocessor. Thus, when the floating point state, or environment is stored as an image into memory, it is also stored as a copy in the additional internal registers. When the state, or environment, is to be restored the necessary information (data and/or instructions) is normally present in the additional registers, thus saving CPU cycles by avoiding reloading the image from memory. The present invention allows for either of the two register sets (or a combination thereof) to be, at a given point in time, the working set, with the other being a shadow register set. All of the memory write cycles are monitored (snooped) to determine if the information in the on-chip image has been altered, since the last store operation. The shadowed register file will allow the state of the floating point register file to be kept 'as is' on the occurrence of a task switch.