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 * This file contains the function WebRtcSpl_ReflCoefToLpc(). 14 * The description header can be found in signal_processing_library.h 15 * 16 */ 17 18 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h" 19 20 void WebRtcSpl_ReflCoefToLpc(const int16_t *k, int use_order, int16_t *a) 21 { 22 int16_t any[WEBRTC_SPL_MAX_LPC_ORDER + 1]; 23 int16_t *aptr, *aptr2, *anyptr; 24 const int16_t *kptr; 25 int m, i; 26 27 kptr = k; 28 *a = 4096; // i.e., (Word16_MAX >> 3)+1. 29 *any = *a; 30 a[1] = *k >> 3; 31 32 for (m = 1; m < use_order; m++) 33 { 34 kptr++; 35 aptr = a; 36 aptr++; 37 aptr2 = &a[m]; 38 anyptr = any; 39 anyptr++; 40 41 any[m + 1] = *kptr >> 3; 42 for (i = 0; i < m; i++) 43 { 44 *anyptr = *aptr + (int16_t)((*aptr2 * *kptr) >> 15); 45 anyptr++; 46 aptr++; 47 aptr2--; 48 } 49 50 aptr = a; 51 anyptr = any; 52 for (i = 0; i < (m + 2); i++) 53 { 54 *aptr = *anyptr; 55 aptr++; 56 anyptr++; 57 } 58 } 59 } 60
