Line data    Source code

       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           0 : 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           0 :     kptr = k;
      28           0 :     *a = 4096; // i.e., (Word16_MAX >> 3)+1.
      29           0 :     *any = *a;
      30           0 :     a[1] = *k >> 3;
      31             : 
      32           0 :     for (m = 1; m < use_order; m++)
      33             :     {
      34           0 :         kptr++;
      35           0 :         aptr = a;
      36           0 :         aptr++;
      37           0 :         aptr2 = &a[m];
      38           0 :         anyptr = any;
      39           0 :         anyptr++;
      40             : 
      41           0 :         any[m + 1] = *kptr >> 3;
      42           0 :         for (i = 0; i < m; i++)
      43             :         {
      44           0 :             *anyptr = *aptr + (int16_t)((*aptr2 * *kptr) >> 15);
      45           0 :             anyptr++;
      46           0 :             aptr++;
      47           0 :             aptr2--;
      48             :         }
      49             : 
      50           0 :         aptr = a;
      51           0 :         anyptr = any;
      52           0 :         for (i = 0; i < (m + 2); i++)
      53             :         {
      54           0 :             *aptr = *anyptr;
      55           0 :             aptr++;
      56           0 :             anyptr++;
      57             :         }
      58             :     }
      59           0 : }