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 WebRtcIlbcfix_GainDequant(int16_t index,int16_t maxIn,int16_t stage)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