Apparatus and method for accessing registers in a processor
AssigneeVIA-Cyrix, Inc.
InventorCharles F. Shelor
Life of this patent
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Abstract
The present invention is generally directed to an apparatus and method for accessing registers within a processor. In accordance with one embodiment, an apparatus and method are provided for a processor in which at least two separate indicia (such as register select lines, register bank identifiers, processor mode identifiers, etc.) are utilized to uniquely identify and access a processor register. In accordance with this embodiment, bit lines of the separate indicia are encoded into a single, mapped set of signal lines, and these encoded signal lines are used to access the register.
Claims12
A processor capable of operating in any of a plurality of operating modes, the processor comprising:
- a plurality w of registers, wherein fewer than w registers are program-accessible during any single mode of operation;
- circuitry having n bits capable of carrying a mode value, wherein the mode value identifies a current operating mode of the processor;
- circuitry having m bits capable of carrying a register value, wherein the register value identifies one of the plurality of registers;
- encoder logic configured to encode the mode value with the register value to generate a mapped value carried on p bits, where p is less than m+n, wherein the mapped value collectively identifies both a register and a current processor operating mode.
In a processor capable of operating in a plurality of modes and having w registers, wherein fewer than w registers are program accessible during the execution of a single instruction, a method comprising:
- encoding a mode value carried on a plurality n of mode-identifying bits with a register value carried on a plurality m of register-select bits to produce a mapped value carried on a plurality p of bits, wherein p is less than the sum of n+m, where the mapped value carried on the p bits collectively defines both a current operating mode and register selection;
- and
- using the encoded plurality of bits to uniquely access any of the w registers.
Dependencies are inferred from the claim text.