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Barrel Shifter Rotator Disclosure Number: IPCOM000038609D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31

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Butler, ND Jones, JW [+details]


The use of multiplexers for shifting data is known and extended here to provide a multi-function shifter rotator. Two designs are given with differing ways the functions are implemented and slightly different functions. The first uses a standard barrel data rotator followed by a mask generator and output multiplexer to output data. The second requires no masker, but the required functions are provided by inserting generated mask data as it is being shifted in each stage of the shifter. A microprocessor designed for high performance bit manipulation requires a powerful bit shifter/rotater capable of shifting or rotating its input by multiple bits in a single operation. Here, we describe two barrel shifter designs using multiplexers, commonly available for gate arrays, to perform the shifting.