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_GainDequant.c
16
17******************************************************************/
18
19#include "defines.h"
20#include "constants.h"
21
22/*----------------------------------------------------------------*
23 *  decoder for quantized gains in the gain-shape coding of
24 *  residual
25 *---------------------------------------------------------------*/
26
27int16_t WebRtcIlbcfix_GainDequant(
28    /* (o) quantized gain value (Q14) */
29    int16_t index, /* (i) quantization index */
30    int16_t maxIn, /* (i) maximum of unquantized gain (Q14) */
31    int16_t stage /* (i) The stage of the search */
32                                                ){
33  int16_t scale;
34  const int16_t *gain;
35
36  /* obtain correct scale factor */
37
38  scale=WEBRTC_SPL_ABS_W16(maxIn);
39  scale = WEBRTC_SPL_MAX(1638, scale);  /* if lower than 0.1, set it to 0.1 */
40
41  /* select the quantization table and return the decoded value */
42  gain = WebRtcIlbcfix_kGain[stage];
43
44  return (int16_t)((scale * gain[index] + 8192) >> 14);
45}
46