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
WebRtcIlbcfix_MyCorr(int32_t * corr,const int16_t * seq1,size_t dim1,const int16_t * seq2,size_t dim2)25 void 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