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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.
*/
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
WebRtcIlbcfix_GetLspPoly.h
******************************************************************/
#ifndef MODULES_AUDIO_CODING_CODECS_ILBC_MAIN_SOURCE_GET_LSP_POLY_H_
#define MODULES_AUDIO_CODING_CODECS_ILBC_MAIN_SOURCE_GET_LSP_POLY_H_
#include <stdint.h>
/*----------------------------------------------------------------*
* Construct the polynomials F1(z) and F2(z) from the LSP
* (Computations are done in Q24)
*
* The expansion is performed using the following recursion:
*
* f[0] = 1;
* tmp = -2.0 * lsp[0];
* f[1] = tmp;
* for (i=2; i<=5; i++) {
* b = -2.0 * lsp[2*i-2];
* f[i] = tmp*f[i-1] + 2.0*f[i-2];
* for (j=i; j>=2; j--) {
* f[j] = f[j] + tmp*f[j-1] + f[j-2];
* }
* f[i] = f[i] + tmp;
* }
*---------------------------------------------------------------*/
void WebRtcIlbcfix_GetLspPoly(int16_t* lsp, /* (i) LSP in Q15 */
int32_t* f); /* (o) polonymial in Q24 */
#endif