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/*
* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
/*
* This file contains the function WebRtcSpl_ReflCoefToLpc().
* The description header can be found in signal_processing_library.h
*
*/
#include "common_audio/signal_processing/include/signal_processing_library.h"
void WebRtcSpl_ReflCoefToLpc(const int16_t *k, int use_order, int16_t *a)
{
int16_t any[WEBRTC_SPL_MAX_LPC_ORDER + 1];
int16_t *aptr, *aptr2, *anyptr;
const int16_t *kptr;
int m, i;
kptr = k;
*a = 4096; // i.e., (Word16_MAX >> 3)+1.
*any = *a;
a[1] = *k >> 3;
for (m = 1; m < use_order; m++)
{
kptr++;
aptr = a;
aptr++;
aptr2 = &a[m];
anyptr = any;
anyptr++;
any[m + 1] = *kptr >> 3;
for (i = 0; i < m; i++)
{
*anyptr = *aptr + (int16_t)((*aptr2 * *kptr) >> 15);
anyptr++;
aptr++;
aptr2--;
}
aptr = a;
anyptr = any;
for (i = 0; i < (m + 2); i++)
{
*aptr = *anyptr;
aptr++;
anyptr++;
}
}
}