Apparatus for executing a plurality of program segments having different object code types in a single program or processor environment
December 18, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesEmulation apparatus Condition register architecture for a primitive instruction set machine Performance enhancement scheme for a RISC type VLSI processor using dual execution units for parallel instruction processing Method and operating system for executing programs in a multi-mode microprocessor Emulation method Method and operating system for executing programs in a multi-mode microprocessor Method of transferring control in a multitasking computer system Method and operating system for executing programs in a multi-mode microprocessor Patent #: 5027273 InventorsAssigneeApplicationNo. 993923 filed on 12/18/1992US Classes:713/100, RECONFIGURATION (E.G., CHANGING SYSTEM SETTING)712/202, Stack based computer712/229Mode switch or changeExaminersPrimary: Heckler, Thomas M.Attorney, Agent or FirmForeign Patent References
International ClassG06F 009/44AbstractThe invention provides a method and apparatus for switching between execution of a plurality of object code types having different conventions for invoking program procedures and performing stack manipulations. The invention may also be used to switch between different calling conventions within a single object code type. Briefly according to the invention, a computer system comprises a routine descriptor, a stack switch frame, a mode switching mechanism for switching from a first processor, code or calling convention type to a second processor, code or calling convention type and means for executing instructions in various code type codes. A routine descriptor describes a program or code segment and its code type and calling conventions. A routine descriptor contains, among other information, a "mixed mode" field which is set to a specific, predetermined value such as a value indicating an instruction which is not legal in the runtime environment of a first processor, code or calling convention type. When that instruction is encountered, control is transferred to the mode switching mechanism. A routine descriptor also contains a "procedure information" field which is set to a value indicating the convention for invoking a program segment and performing appropriate stack manipulations. When a routine calls a routine having a different stack model, the mode switching mechanism uses a stack switch frame to provide a transition between the two different stack types.Other References
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