Efficient 32-bit based case table support for 64-bit architectur

Details Efficient 32-bit based case table support for 64-bit architectur Efficient 32-bit based case table support for 64-bit architectur

1996-04-30

1998-11-10

Trammell, James P.

395709, 395500, G06F 945

Patent

active

058357742

ABSTRACT:
The present invention describes a system and method to efficiently implement case table constructs for integral datatypes larger than the native underlying register size of the architecture. The method for generating case table constructs for a n-bit case variable on a computer system having a m-bit architecture, where n is greater than m, includes the step of determining whether the n-bit case variable can be represented in m bits. Since the code for a m-bit case variable is more efficient than the code for a n-bit case variable, the present invention determines which case variables require code for n-bit values and which case variables can be implemented in the more efficient code for m-bit values. If the case variable can be reduced to m-bits then the present invention uses the more efficient m-bit case variable code for implementation. Otherwise, the less efficient n-bit case variable code is used. The invention describes an efficient method for performing this test at runtime.

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