253 lines
9.1 KiB
C
253 lines
9.1 KiB
C
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/* -----------------------------------------------------------------------------------------------------------
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Software License for The Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android
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© Copyright 1995 - 2013 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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All rights reserved.
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1. INTRODUCTION
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The Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements
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the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio.
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This FDK AAC Codec software is intended to be used on a wide variety of Android devices.
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AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual
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audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by
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independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part
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of the MPEG specifications.
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Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer)
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may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners
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individually for the purpose of encoding or decoding bit streams in products that are compliant with
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the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license
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these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec
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software may already be covered under those patent licenses when it is used for those licensed purposes only.
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Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality,
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are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional
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applications information and documentation.
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2. COPYRIGHT LICENSE
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Redistribution and use in source and binary forms, with or without modification, are permitted without
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payment of copyright license fees provided that you satisfy the following conditions:
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You must retain the complete text of this software license in redistributions of the FDK AAC Codec or
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your modifications thereto in source code form.
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You must retain the complete text of this software license in the documentation and/or other materials
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provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form.
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You must make available free of charge copies of the complete source code of the FDK AAC Codec and your
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modifications thereto to recipients of copies in binary form.
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The name of Fraunhofer may not be used to endorse or promote products derived from this library without
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prior written permission.
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You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec
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software or your modifications thereto.
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Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software
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and the date of any change. For modified versions of the FDK AAC Codec, the term
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"Fraunhofer FDK AAC Codec Library for Android" must be replaced by the term
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"Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android."
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3. NO PATENT LICENSE
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NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer,
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ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with
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respect to this software.
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You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized
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by appropriate patent licenses.
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4. DISCLAIMER
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This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors
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"AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the implied warranties
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of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages,
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including but not limited to procurement of substitute goods or services; loss of use, data, or profits,
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or business interruption, however caused and on any theory of liability, whether in contract, strict
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liability, or tort (including negligence), arising in any way out of the use of this software, even if
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advised of the possibility of such damage.
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5. CONTACT INFORMATION
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Fraunhofer Institute for Integrated Circuits IIS
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Attention: Audio and Multimedia Departments - FDK AAC LL
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Am Wolfsmantel 33
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91058 Erlangen, Germany
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www.iis.fraunhofer.de/amm
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amm-info@iis.fraunhofer.de
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----------------------------------------------------------------------------------------------------------- */
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/*************************** Fraunhofer IIS FDK Tools **********************
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Author(s): Josef Hoepfl, DSP Solutions
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Description: Fix point FFT
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******************************************************************************/
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#ifndef __FFT_H__
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#define __FFT_H__
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#include "common_fix.h"
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/**
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* \brief Perform an inplace complex valued FFT of length 2^n
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*
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* \param length Length of the FFT to be calculated.
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* \param pInput Input/Output data buffer. The input data must have at least 1 bit scale headroom.
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* The values are interleaved, real/imag pairs.
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* \param scalefactor Pointer to an INT, which contains the current scale of the input data,
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* which is updated according to the FFT scale.
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*/
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void fft(int length, FIXP_DBL *pInput, INT *scalefactor);
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/**
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* \brief Perform an inplace complex valued IFFT of length 2^n
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*
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* \param length Length of the FFT to be calculated.
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* \param pInput Input/Output data buffer. The input data must have at least 1 bit scale headroom.
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* The values are interleaved, real/imag pairs.
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* \param scalefactor Pointer to an INT, which contains the current scale of the input data,
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* which is updated according to the IFFT scale.
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*/
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void ifft(int length, FIXP_DBL *pInput, INT *scalefactor);
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/*
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* Frequently used and fixed short length FFTs.
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*/
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LNK_SECTION_CODE_L1
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static FORCEINLINE void fft_4(FIXP_DBL *x)
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{
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FIXP_DBL a00, a10, a20, a30, tmp0, tmp1;
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a00 = (x[0] + x[4])>>1; /* Re A + Re B */
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a10 = (x[2] + x[6])>>1; /* Re C + Re D */
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a20 = (x[1] + x[5])>>1; /* Im A + Im B */
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a30 = (x[3] + x[7])>>1; /* Im C + Im D */
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x[0] = a00 + a10; /* Re A' = Re A + Re B + Re C + Re D */
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x[1] = a20 + a30; /* Im A' = Im A + Im B + Im C + Im D */
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tmp0 = a00 - x[4]; /* Re A - Re B */
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tmp1 = a20 - x[5]; /* Im A - Im B */
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x[4] = a00 - a10; /* Re C' = Re A + Re B - Re C - Re D */
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x[5] = a20 - a30; /* Im C' = Im A + Im B - Im C - Im D */
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a10 = a10 - x[6]; /* Re C - Re D */
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a30 = a30 - x[7]; /* Im C - Im D */
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x[2] = tmp0 + a30; /* Re B' = Re A - Re B + Im C - Im D */
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x[6] = tmp0 - a30; /* Re D' = Re A - Re B - Im C + Im D */
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x[3] = tmp1 - a10; /* Im B' = Im A - Im B - Re C + Re D */
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x[7] = tmp1 + a10; /* Im D' = Im A - Im B + Re C - Re D */
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}
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LNK_SECTION_CODE_L1
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static FORCEINLINE void fft_8(FIXP_DBL *x)
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{
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#define W_PiFOURTH STC(0x5a82799a)
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FIXP_DBL a00, a10, a20, a30;
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FIXP_DBL y[16];
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a00 = (x[0] + x[8])>>1;
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a10 = x[4] + x[12];
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a20 = (x[1] + x[9])>>1;
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a30 = x[5] + x[13];
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y[0] = a00 + (a10>>1);
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y[4] = a00 - (a10>>1);
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y[1] = a20 + (a30>>1);
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y[5] = a20 - (a30>>1);
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a00 = a00 - x[8];
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a10 = (a10>>1) - x[12];
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a20 = a20 - x[9];
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a30 = (a30>>1) - x[13];
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y[2] = a00 + a30;
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y[6] = a00 - a30;
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y[3] = a20 - a10;
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y[7] = a20 + a10;
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a00 = (x[2] + x[10])>>1;
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a10 = x[6] + x[14];
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a20 = (x[3] + x[11])>>1;
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a30 = x[7] + x[15];
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y[8] = a00 + (a10>>1);
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y[12] = a00 - (a10>>1);
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y[9] = a20 + (a30>>1);
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y[13] = a20 - (a30>>1);
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a00 = a00 - x[10];
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a10 = (a10>>1) - x[14];
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a20 = a20 - x[11];
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a30 = (a30>>1) - x[15];
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y[10] = a00 + a30;
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y[14] = a00 - a30;
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y[11] = a20 - a10;
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y[15] = a20 + a10;
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FIXP_DBL vr, vi, ur, ui;
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ur = y[0]>>1;
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ui = y[1]>>1;
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vr = y[8];
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vi = y[9];
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x[0] = ur + (vr>>1);
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x[1] = ui + (vi>>1);
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x[8] = ur - (vr>>1);
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x[9] = ui - (vi>>1);
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ur = y[4]>>1;
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ui = y[5]>>1;
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vi = y[12];
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vr = y[13];
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x[4] = ur + (vr>>1);
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x[5] = ui - (vi>>1);
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x[12] = ur - (vr>>1);
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x[13] = ui + (vi>>1);
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ur = y[10];
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ui = y[11];
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vr = fMultDiv2(ui+ur,W_PiFOURTH);
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vi = fMultDiv2(ui-ur,W_PiFOURTH);
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ur = y[2];
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ui = y[3];
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x[2] = (ur>>1) + vr;
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x[3] = (ui>>1) + vi;
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x[10] = (ur>>1) - vr;
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x[11] = (ui>>1) - vi;
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ur = y[14];
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ui = y[15];
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vr = fMultDiv2(ui-ur,W_PiFOURTH);
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vi = fMultDiv2(ui+ur,W_PiFOURTH);
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ur = y[6];
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ui = y[7];
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x[6] = (ur>>1) + vr;
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x[7] = (ui>>1) - vi;
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x[14] = (ur>>1) - vr;
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x[15] = (ui>>1) + vi;
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}
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/**
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* \brief FFT of fixed length 16
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*/
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inline void fft_16(FIXP_DBL *x);
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/**
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* \brief FFT of fixed length 32
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*/
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inline void fft_32(FIXP_DBL *x);
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#endif
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