A Depth-First Iterative Algorithm for the Conjugate Pair Fast Fourier Transform

The Split-Radix Fast Fourier Transform has the same low arithmetic complexity as related Conjugate Pair Transform. Both transforms have an irregular datapath structure which is straightforwardly expressed only in recursive forms. Furthermore, conjugate pair variant a complicated input indexing pattern requires existing iterative implementations to rely on precomputed tables. It however allows optimization of memory bandwidth it single twiddle factor load per radix-4 butterfly. In algorithms, this comes at cost using additional tables or performing function calls. paper we present two novel approaches that handle both butterfly scheduling and index generation proposed algorithm cache-friendly because depth-first, non-recursive does not order achieve this, relate execution FFTs binary carry sequence. Based finding, describe how common integer bitwise operations can be used perform reordering depth-first traversal transform with O(1) space complexity.