Versatile data shifter with sticky bit generation capability

摘要

A barrel-shift data shifter structure is modified to segregate switches in a switching matrix included therein into those switches as participate in a simple shift as well as in a barrel shift and those switches used only in a barrel shift. The former set of switches is controlled by shift control signals alone, and the latter set of switches responds to shift control signals and to the presence or absence of a rotation enable signal. The number of switches required is substantially smaller than required in a barrel shifter followed in cascade by a simple data shifter. Preferably provision is made for sticky bit generation. The sticky bit is the LOGIC OR response to all bits shifted to less significance than output data.