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_CompCorr.c
16
17******************************************************************/
18
19#include "defines.h"
20
21/*----------------------------------------------------------------*
22 *  Compute cross correlation and pitch gain for pitch prediction
23 *  of last subframe at given lag.
24 *---------------------------------------------------------------*/
25
26void WebRtcIlbcfix_CompCorr(
27    int32_t *corr, /* (o) cross correlation */
28    int32_t *ener, /* (o) energy */
29    int16_t *buffer, /* (i) signal buffer */
30    int16_t lag,  /* (i) pitch lag */
31    int16_t bLen, /* (i) length of buffer */
32    int16_t sRange, /* (i) correlation search length */
33    int16_t scale /* (i) number of rightshifts to use */
34                            ){
35  int16_t *w16ptr;
36
37  w16ptr=&buffer[bLen-sRange-lag];
38
39  /* Calculate correlation and energy */
40  (*corr)=WebRtcSpl_DotProductWithScale(&buffer[bLen-sRange], w16ptr, sRange, scale);
41  (*ener)=WebRtcSpl_DotProductWithScale(w16ptr, w16ptr, sRange, scale);
42
43  /* For zero energy set the energy to 0 in order to avoid potential
44     problems for coming divisions */
45  if (*ener == 0) {
46    *corr = 0;
47    *ener = 1;
48  }
49}
50