1 /* 2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 12 /* 13 * This file contains the function WebRtcSpl_ComplexBitReverse(). 14 * The description header can be found in signal_processing_library.h 15 * 16 */ 17 18 #include "signal_processing_library.h" 19 WebRtcSpl_ComplexBitReverse(WebRtc_Word16 frfi[],int stages)20 void WebRtcSpl_ComplexBitReverse(WebRtc_Word16 frfi[], int stages) 21 { 22 int mr, nn, n, l, m; 23 WebRtc_Word16 tr, ti; 24 25 n = 1 << stages; 26 27 mr = 0; 28 nn = n - 1; 29 30 // decimation in time - re-order data 31 for (m = 1; m <= nn; ++m) 32 { 33 l = n; 34 do 35 { 36 l >>= 1; 37 } while (mr + l > nn); 38 mr = (mr & (l - 1)) + l; 39 40 if (mr <= m) 41 continue; 42 43 tr = frfi[2 * m]; 44 frfi[2 * m] = frfi[2 * mr]; 45 frfi[2 * mr] = tr; 46 47 ti = frfi[2 * m + 1]; 48 frfi[2 * m + 1] = frfi[2 * mr + 1]; 49 frfi[2 * mr + 1] = ti; 50 } 51 } 52