git-svn-id: http://webrtc.googlecode.com/svn/trunk@2 4adac7df-926f-26a2-2b94-8c16560cd09d

common_audio/signal_processing_library/main/source/randomization_functions.c

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+/*
+ *  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 implementations of the randomization functions
+ * WebRtcSpl_IncreaseSeed()
+ * WebRtcSpl_RandU()
+ * WebRtcSpl_RandN()
+ * WebRtcSpl_RandUArray()
+ *
+ * The description header can be found in signal_processing_library.h
+ *
+ */
+
+#include "signal_processing_library.h"
+
+WebRtc_UWord32 WebRtcSpl_IncreaseSeed(WebRtc_UWord32 *seed)
+{
+    seed[0] = (seed[0] * ((WebRtc_Word32)69069) + 1) & (WEBRTC_SPL_MAX_SEED_USED - 1);
+    return seed[0];
+}
+
+WebRtc_Word16 WebRtcSpl_RandU(WebRtc_UWord32 *seed)
+{
+    return (WebRtc_Word16)(WebRtcSpl_IncreaseSeed(seed) >> 16);
+}
+
+WebRtc_Word16 WebRtcSpl_RandN(WebRtc_UWord32 *seed)
+{
+    return WebRtcSpl_kRandNTable[WebRtcSpl_IncreaseSeed(seed) >> 23];
+}
+
+// Creates an array of uniformly distributed variables
+WebRtc_Word16 WebRtcSpl_RandUArray(WebRtc_Word16* vector,
+                                   WebRtc_Word16 vector_length,
+                                   WebRtc_UWord32* seed)
+{
+    int i;
+    for (i = 0; i < vector_length; i++)
+    {
+        vector[i] = WebRtcSpl_RandU(seed);
+    }
+    return vector_length;
+}