1 files changed, 141 insertions, 0 deletions
diff --git a/src/common_audio/signal_processing_library/main/source/auto_correlation.c b/src/common_audio/signal_processing_library/main/source/auto_correlation.c
new file mode 100644
index 0000000000..a00fde4bc3
--- /dev/null
+++ b/src/common_audio/signal_processing_library/main/source/auto_correlation.c
@@ -0,0 +1,141 @@
+/*
+ *  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_AutoCorrelation().
+ * The description header can be found in signal_processing_library.h
+ *
+ */
+
+#include "signal_processing_library.h"
+
+int WebRtcSpl_AutoCorrelation(G_CONST WebRtc_Word16* in_vector,
+                              int in_vector_length,
+                              int order,
+                              WebRtc_Word32* result,
+                              int* scale)
+{
+    WebRtc_Word32 sum;
+    int i, j;
+    WebRtc_Word16 smax; // Sample max
+    G_CONST WebRtc_Word16* xptr1;
+    G_CONST WebRtc_Word16* xptr2;
+    WebRtc_Word32* resultptr;
+    int scaling = 0;
+
+#ifdef _ARM_OPT_
+#pragma message("NOTE: _ARM_OPT_ optimizations are used")
+    WebRtc_Word16 loops4;
+#endif
+
+    if (order < 0)
+        order = in_vector_length;
+
+    // Find the max. sample
+    smax = WebRtcSpl_MaxAbsValueW16(in_vector, in_vector_length);
+
+    // In order to avoid overflow when computing the sum we should scale the samples so that
+    // (in_vector_length * smax * smax) will not overflow.
+
+    if (smax == 0)
+    {
+        scaling = 0;
+    } else
+    {
+        int nbits = WebRtcSpl_GetSizeInBits(in_vector_length); // # of bits in the sum loop
+        int t = WebRtcSpl_NormW32(WEBRTC_SPL_MUL(smax, smax)); // # of bits to normalize smax
+
+        if (t > nbits)
+        {
+            scaling = 0;
+        } else
+        {
+            scaling = nbits - t;
+        }
+
+    }
+
+    resultptr = result;
+
+    // Perform the actual correlation calculation
+    for (i = 0; i < order + 1; i++)
+    {
+        int loops = (in_vector_length - i);
+        sum = 0;
+        xptr1 = in_vector;
+        xptr2 = &in_vector[i];
+#ifndef _ARM_OPT_
+        for (j = loops; j > 0; j--)
+        {
+            sum += WEBRTC_SPL_MUL_16_16_RSFT(*xptr1++, *xptr2++, scaling);
+        }
+#else
+        loops4 = (loops >> 2) << 2;
+
+        if (scaling == 0)
+        {
+            for (j = 0; j < loops4; j = j + 4)
+            {
+                sum += WEBRTC_SPL_MUL_16_16(*xptr1, *xptr2);
+                xptr1++;
+                xptr2++;
+                sum += WEBRTC_SPL_MUL_16_16(*xptr1, *xptr2);
+                xptr1++;
+                xptr2++;
+                sum += WEBRTC_SPL_MUL_16_16(*xptr1, *xptr2);
+                xptr1++;
+                xptr2++;
+                sum += WEBRTC_SPL_MUL_16_16(*xptr1, *xptr2);
+                xptr1++;
+                xptr2++;
+            }
+
+            for (j = loops4; j < loops; j++)
+            {
+                sum += WEBRTC_SPL_MUL_16_16(*xptr1, *xptr2);
+                xptr1++;
+                xptr2++;
+            }
+        }
+        else
+        {
+            for (j = 0; j < loops4; j = j + 4)
+            {
+                sum += WEBRTC_SPL_MUL_16_16_RSFT(*xptr1, *xptr2, scaling);
+                xptr1++;
+                xptr2++;
+                sum += WEBRTC_SPL_MUL_16_16_RSFT(*xptr1, *xptr2, scaling);
+                xptr1++;
+                xptr2++;
+                sum += WEBRTC_SPL_MUL_16_16_RSFT(*xptr1, *xptr2, scaling);
+                xptr1++;
+                xptr2++;
+                sum += WEBRTC_SPL_MUL_16_16_RSFT(*xptr1, *xptr2, scaling);
+                xptr1++;
+                xptr2++;
+            }
+
+            for (j = loops4; j < loops; j++)
+            {
+                sum += WEBRTC_SPL_MUL_16_16_RSFT(*xptr1, *xptr2, scaling);
+                xptr1++;
+                xptr2++;
+            }
+        }
+
+#endif
+        *resultptr++ = sum;
+    }
+
+    *scale = scaling;
+
+    return order + 1;
+}