A data processing device and a method for performing second or next stage of an N point Fast Fourier Transform is suggested. The processing device comprises an input operand memory unit and an input buffer comprising a plurality of addressable memory cells arranged in lines and columns. Furthermore, the device comprises a number of radix-P operation units for producing output operands that are buffered in an output buffer. Input operands are read from the input operand memory unit and buffering into the input buffer. The input operands are stored and fetched from the input buffer according to a reordering scheme that allows efficient parallel processing of the operands by the butterflies and the buffering of subsequent input operands.