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gnss-sdr/src/algorithms/libs/gps_sdr_fft.h

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/*----------------------------------------------------------------------------------------------*/
/*! \file fft.h
//
// FILENAME: fft.h
//
// DESCRIPTION: Defines the FFT class.
//
// DEVELOPERS: Gregory W. Heckler (2003-2009)
//
// LICENSE TERMS: Copyright (c) Gregory W. Heckler 2009
//
// This file is part of the GPS Software Defined Radio (GPS-SDR)
//
// The GPS-SDR is free software; you can redistribute it and/or modify it under the terms of the
// GNU General Public License as published by the Free Software Foundation; either version 2 of
// the License, or (at your option) any later version. The GPS-SDR is distributed in the hope that
// it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// Note: Comments within this file follow a syntax that is compatible with
// DOXYGEN and are utilized for automated document extraction
//
// Reference:
*/
/*----------------------------------------------------------------------------------------------*/
#ifndef FFT_H_
#define FFT_H_
#include "gps_sdr_defines.h"
#include "gps_sdr_signal_processing.h"
#define MAX_RANKS (16)
/*! @ingroup CLASSES
@brief /xyzzy */
class FFT
{
private:
MIX *W; //!< Twiddle lookup array for FFT
MIX *iW; //!< Twiddle lookup array for iFFT
int32 *BRX; //!< Re-order temp array
int32 *BR; //!< Re-order index array
int32 N; //!< Length (should be 2^N!!!)
int32 M; //!< Log2(N) (number of ranks)
int32 R[16]; //!< Programmable rank scaling
void initW(); //!< Initialize twiddles
void initBR(); //!< Initialize re-order array
void doShuffle(CPX *_x); //!< Do bit-reverse shuffling
public:
FFT(); //!< Initialize FFT
FFT(int32 _N); //!< Initialize FFT for 2^N
FFT(int32 _N, int32 _R[MAX_RANKS]); //!< Initialize FFT for 2^N, with ranks
~FFT(); //!< Destructor
void doFFT(CPX *_x, bool _shuf); //!< Forward FFT, decimate in time
void doiFFT(CPX *_x, bool _shuf); //!< Inverse FFT, decimate in time
void doFFTdf(CPX *_x, bool _shuf); //!< Forward FFT, decimate in frequency
void doiFFTdf(CPX *_x, bool _shuf); //!< Inverse FFT, decimate in frequency
};
#endif /*FFT_H_*/