Method and apparatus for conditionally generating a microinstruction that selects one of two values based upon control states of a microprocessor
US5537560A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 1994 |
| Grant date | Jul 16, 1996 |
| Priority date | — |
| Expiry date | Mar 1, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/3842
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The present invention provides a microinstruction for conditionally selecting one of two data values based upon control states of a processor. The microinstruction is preferably utilized in an out-of-order processor, although it may be used in conventional processors, to perform state dependent operations, including but not limited to privilege or mode sensitive instruction checking, privilege or mode sensitive algorithm execution and processor state updating. This is accomplished through the issuance from microcode to an execution unit upon decoding of a state dependent instruction a conditional move operation that takes advantage of condition resolving circuitry implemented within the execution unit. The execution unit's circuitry makes available processor state information in the form of result values that can be immediately used by the microinstruction upon its execution to resolve the conditions which it specifies. Upon immediate resolution of a specified condition, one of two values (or microcode temporary registers having values therein) is selected in order to properly complete the state dependent operation or to take other appropriate action such as posting a fault.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.