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_InterpolateSamples.c
16 
17 ******************************************************************/
18 
19 #include "defines.h"
20 #include "constants.h"
21 
WebRtcIlbcfix_InterpolateSamples(int16_t * interpSamples,int16_t * CBmem,size_t lMem)22 void WebRtcIlbcfix_InterpolateSamples(
23     int16_t *interpSamples, /* (o) The interpolated samples */
24     int16_t *CBmem,   /* (i) The CB memory */
25     size_t lMem    /* (i) Length of the CB memory */
26                                       ) {
27   int16_t *ppi, *ppo, i, j, temp1, temp2;
28   int16_t *tmpPtr;
29 
30   /* Calculate the 20 vectors of interpolated samples (4 samples each)
31      that are used in the codebooks for lag 20 to 39 */
32   tmpPtr = interpSamples;
33   for (j=0; j<20; j++) {
34     temp1 = 0;
35     temp2 = 3;
36     ppo = CBmem+lMem-4;
37     ppi = CBmem+lMem-j-24;
38     for (i=0; i<4; i++) {
39 
40       *tmpPtr++ = (int16_t)((WebRtcIlbcfix_kAlpha[temp2] * *ppo) >> 15) +
41           (int16_t)((WebRtcIlbcfix_kAlpha[temp1] * *ppi) >> 15);
42 
43       ppo++;
44       ppi++;
45       temp1++;
46       temp2--;
47     }
48   }
49 
50   return;
51 }
52