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_SimpleLsfDeQ.c
16 
17 ******************************************************************/
18 
19 #include "defines.h"
20 #include "constants.h"
21 
22 /*----------------------------------------------------------------*
23  *  obtain dequantized lsf coefficients from quantization index
24  *---------------------------------------------------------------*/
25 
WebRtcIlbcfix_SimpleLsfDeQ(int16_t * lsfdeq,int16_t * index,int16_t lpc_n)26 void WebRtcIlbcfix_SimpleLsfDeQ(
27     int16_t *lsfdeq,  /* (o) dequantized lsf coefficients */
28     int16_t *index,  /* (i) quantization index */
29     int16_t lpc_n  /* (i) number of LPCs */
30                                 ){
31   int i, j, pos, cb_pos;
32 
33   /* decode first LSF */
34 
35   pos = 0;
36   cb_pos = 0;
37   for (i = 0; i < LSF_NSPLIT; i++) {
38     for (j = 0; j < WebRtcIlbcfix_kLsfDimCb[i]; j++) {
39       lsfdeq[pos + j] = WebRtcIlbcfix_kLsfCb[cb_pos + j + index[i] *
40                                              WebRtcIlbcfix_kLsfDimCb[i]];
41     }
42     pos += WebRtcIlbcfix_kLsfDimCb[i];
43     cb_pos += WebRtcIlbcfix_kLsfSizeCb[i] * WebRtcIlbcfix_kLsfDimCb[i];
44   }
45 
46   if (lpc_n>1) {
47     /* decode last LSF */
48     pos = 0;
49     cb_pos = 0;
50     for (i = 0; i < LSF_NSPLIT; i++) {
51       for (j = 0; j < WebRtcIlbcfix_kLsfDimCb[i]; j++) {
52         lsfdeq[LPC_FILTERORDER + pos + j] = WebRtcIlbcfix_kLsfCb[
53             cb_pos + index[LSF_NSPLIT + i] * WebRtcIlbcfix_kLsfDimCb[i] + j];
54       }
55       pos += WebRtcIlbcfix_kLsfDimCb[i];
56       cb_pos += WebRtcIlbcfix_kLsfSizeCb[i] * WebRtcIlbcfix_kLsfDimCb[i];
57     }
58   }
59   return;
60 }
61