PURPOSE: To omit the useless shifting operation of a shift instruction and to obtain required shift data only by one step operation by previously specifying masking/padding information or the like on both the right and left sides of a data string.

CONSTITUTION: In the case of obtaining a required shift data string by a data register 1, an FF 20 on the right side indicates patting at the time of setting up it and a specified pattering length value is set up in a register 2 indicating the padding length. An FF 21 on the left side indicates masking at the time of resetting it and a specified mask length value is set up in a register 3 indicating the mask length. In addition, a specified shifting direction and the specified number of shifts are set up in a register 4 indicating the shifting direction and the number of shifts. A masking/padding information forming circuit 5 generates a masking signal and a padding signal based upon the values of the resistors 2, 3 and an objective shift data can be obtained through selection circuits 6 to 13 or the like. Thus the required shift data string can be obtained only by one step operation.