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 iLBC Speech Coder ANSI-C Source Code
14
15 WebRtcIlbcfix_MyCorr.c
16
17******************************************************************/
18
19#include "defines.h"
20
21/*----------------------------------------------------------------*
22 * compute cross correlation between sequences
23 *---------------------------------------------------------------*/
24
25void WebRtcIlbcfix_MyCorr(
26    int32_t* corr,  /* (o) correlation of seq1 and seq2 */
27    const int16_t* seq1,  /* (i) first sequence */
28    size_t dim1,  /* (i) dimension first seq1 */
29    const int16_t* seq2, /* (i) second sequence */
30    size_t dim2   /* (i) dimension seq2 */
31                          ){
32  int16_t max;
33  size_t loops;
34  int scale;
35
36  /* Calculate correlation between the two sequences. Scale the
37     result of the multiplcication to maximum 26 bits in order
38     to avoid overflow */
39  max=WebRtcSpl_MaxAbsValueW16(seq1, dim1);
40  scale=WebRtcSpl_GetSizeInBits(max);
41
42  scale = 2 * scale - 26;
43  if (scale<0) {
44    scale=0;
45  }
46
47  loops=dim1-dim2+1;
48
49  /* Calculate the cross correlations */
50  WebRtcSpl_CrossCorrelation(corr, seq2, seq1, dim2, loops, scale, 1);
51
52  return;
53}
54