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_Interpolate.c
16 
17 ******************************************************************/
18 
19 #include "modules/audio_coding/codecs/ilbc/interpolate.h"
20 
21 #include "modules/audio_coding/codecs/ilbc/constants.h"
22 #include "modules/audio_coding/codecs/ilbc/defines.h"
23 
24 /*----------------------------------------------------------------*
25  *  interpolation between vectors
26  *---------------------------------------------------------------*/
27 
WebRtcIlbcfix_Interpolate(int16_t * out,int16_t * in1,int16_t * in2,int16_t coef,int16_t length)28 void WebRtcIlbcfix_Interpolate(
29     int16_t *out, /* (o) output vector */
30     int16_t *in1, /* (i) first input vector */
31     int16_t *in2, /* (i) second input vector */
32     int16_t coef, /* (i) weight coefficient in Q14 */
33     int16_t length)  /* (i) number of sample is vectors */
34 {
35   int i;
36   int16_t invcoef;
37 
38   /*
39     Performs the operation out[i] = in[i]*coef + (1-coef)*in2[i] (with rounding)
40   */
41 
42   invcoef = 16384 - coef; /* 16384 = 1.0 (Q14)*/
43   for (i = 0; i < length; i++) {
44     out[i] = (int16_t)((coef * in1[i] + invcoef * in2[i] + 8192) >> 14);
45   }
46 
47   return;
48 }
49