Global rotation of data in synchronous vector processor

Abstract

An apparatus and method for performing rotation of data in a register file memory. The apparatus utilizes a rotation address generator including rotation value, modulus, and offset registers, a comparator, a data selector, logic circuitry, and a subtractor. A predetermined area (P.times.Q) of the register file memory and a rotation value corresponding to the number of bits to be rotated in the rotation area is designated by an instruction program memory. An instruction decoder signals the register file, modulus register, rotation value register, and offset register of an impending rotation of data, thereby enabling loading of the modulus and rotation value registers and resetting of the offset register. A counter provides a relative address to the comparator and data selector. The comparator compares the relative address with the output of the modulus register, determining whether selected ones of the addressed register file locations fall inside or outside of the rotation area, and send an appropriate signal to the logic circuitry, an OR gate. This OR gate also receives a rotate or not-rotate signal. Consequently, either an absolute address equal to (the value of the relative address-2 * the offset value) mod (8 * the value in the modulus register) or equal to the relative address, based on predetermined conditions, is utilized to access rotationally data from the register file.