A data processing system (10) has a control selector (30) which has at least one conductor used for the common functions of shifting data and controling the generation of constants in an execution unit (26). A logic circuit (34) provides control signals to enable the control selector (30) to perform an information transfer, a shift operation, or a constant generation function. A plurality of constant signals enables a plurality of transistors (82, 114, 130, 84, 132, 86, 134) to generate a plurality of constant values. During an operation to shift data, a portion of the logic circuit (30) which generates a constant value is disabled by a Shift Disable signal. The conductors used to enable the control electrodes of the transistors during a constant generation function are used to shift data a predetermined number of bits when two shift signals are asserted.