Abstract :
This paper will discuss combinatorial uniform shift networks that can shift a binary word a variable number of bit positions. Typical arithmetic applications are for prenormalization or alignment of one of the mantissas in floating point addition, postnormalization of the mantissa in any normalized floating point operation, or for one or more bits of shifting in multiply and divide. Other applications include • packing and unpacking of fields stored in memory either within the processor itself or as part of a separate unit between the processor and the memory (such a unit, called a "field isolation unit," is described by DeSantis, et al1); • isolation of fields of a word in the instruction decoding and break-apart done during emulation of various machines; and • variable-length routing of words between all processors in an array computer by transposing the processor/data word matrix, shifting by the routing distance, and transposing the resultant data word/processor matrix back, as described by Semmelhaack.2
