1 files changed, 51 insertions, 0 deletions
diff --git a/src/common_audio/signal_processing/complex_bit_reverse.c b/src/common_audio/signal_processing/complex_bit_reverse.c
new file mode 100644
index 0000000000..85c76f8283
--- /dev/null
+++ b/src/common_audio/signal_processing/complex_bit_reverse.c
@@ -0,0 +1,51 @@
+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+
+/*
+ * This file contains the function WebRtcSpl_ComplexBitReverse().
+ * The description header can be found in signal_processing_library.h
+ *
+ */
+
+#include "signal_processing_library.h"
+
+void WebRtcSpl_ComplexBitReverse(WebRtc_Word16 frfi[], int stages)
+{
+    int mr, nn, n, l, m;
+    WebRtc_Word16 tr, ti;
+
+    n = 1 << stages;
+
+    mr = 0;
+    nn = n - 1;
+
+    // decimation in time - re-order data
+    for (m = 1; m <= nn; ++m)
+    {
+        l = n;
+        do
+        {
+            l >>= 1;
+        } while (mr + l > nn);
+        mr = (mr & (l - 1)) + l;
+
+        if (mr <= m)
+            continue;
+
+        tr = frfi[2 * m];
+        frfi[2 * m] = frfi[2 * mr];
+        frfi[2 * mr] = tr;
+
+        ti = frfi[2 * m + 1];
+        frfi[2 * m + 1] = frfi[2 * mr + 1];
+        frfi[2 * mr + 1] = ti;
+    }
+}