FFT_Wrapper.h

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///
///  FFT_Wrapper.h -- wrapper class for FFTs that hides implementation details
///     This class can be used with FFTW, FFTReal, or other FFT implementations.
///     It assumes real-values float vectors as input to the FFT, and can deliver
///     real or complex results in several formats (complex #s or mag/phase).
///     The IFFT assumes complex input and delivers real-valued output.
///
///     The API is minimal, with a constructor method and the work-horse
///     nextBuffer(Buffer & in, Buffer & out) method doing a single FFT or IFFT
///
///     This file includes both the abstract wrapper, and the 3 standard concrete subclasses.
///     Compile this with one of the API flags defined in the compiler (-DUSE_FFTW), or define it below.
///     There are 3 standard concrete subclasses: 
///         RealFFT (RealFFT code included in CSL), and 
///         FFTW (assumes fftw3f is installed), 
///         KISS FFT, built-in FFT from Laurent de Soras (included, untested).
///
/// See the copyright notice and acknowledgment of authors in the file COPYRIGHT
///

#ifndef CSL_FFT_WRAPPER_H
#define CSL_FFT_WRAPPER_H

                // I use compiler flags for these, so different apps can share the same code base.
//#define USE_FFTW                          // use FFTW (faster but complicated to build)
//#define USE_FFTREAL                       // use FFTReal (smaller and simpler)
//#define USE_KISSFFT                       // use KISS FFT (smaller and simpler)

#include "CSL_Core.h"

#ifdef USE_FFTW
    #include <fftw3.h>
    #define FFTWrapper FFTW_Wrapper         // which FFT wrapper class to use?
    #define FFTWF_FLAGS FFTW_MEASURE        // or use FFTW_ESTIMATE; FFTW_PRESERVE_INPUT not necessary
#endif

#ifdef USE_FFTREAL
    #include <FFTReal.h>
    #define FFTWrapper FFTR_Wrapper 
#endif

#ifdef USE_KISSFFT
    #include <kiss_fft.h>
    #define FFTWrapper KISSFFT_Wrapper  
#endif

namespace csl {

/// real/complex flag (determines results from forward FFT)

typedef enum {          
    CSL_FFT_REAL = 0,
    CSL_FFT_COMPLEX,
    CSL_FFT_MAGPHASE
} CSL_FFTType;

/// forward/reverse flag (determines FFT direction)

typedef enum {          
    CSL_FFT_FORWARD = 0,
    CSL_FFT_INVERSE
} CSL_FFTDir;

///
/// Abstract FFT class can do forward/reverse real/complex I/O FFTs
///

class Abst_FFT_W {
public:                         /// Constuctor sets up twiddle factor tables
    Abst_FFT_W(unsigned size, CSL_FFTType type = CSL_FFT_REAL, CSL_FFTDir dir = CSL_FFT_FORWARD) 
                : mSize(size), mCSize((size / 2) + 1), mType(type), mDirection(dir) { };

    virtual ~Abst_FFT_W() { };          ///< destructor frees tables

                                /// run the transform between in and out
    virtual void nextBuffer(Buffer & in, Buffer & out) throw (CException) = 0;

    unsigned mSize;             ///< FFT length
    unsigned mCSize;            ///< FFT length / 2 + 1
protected:
    CSL_FFTType mType;          ///< real/complex output
    CSL_FFTDir mDirection;      ///< forward/reverse
};

//
// FFTW-wrapper concrete subclass
//

#ifdef USE_FFTW

class FFTW_Wrapper : public Abst_FFT_W {
public:
    FFTW_Wrapper(unsigned size, CSL_FFTType type = CSL_FFT_REAL, CSL_FFTDir forward = CSL_FFT_FORWARD);
    ~FFTW_Wrapper();
                                /// run the transform between in and out
    void nextBuffer(Buffer & in, Buffer & out) throw (CException);

private:        
//  SampleBuffer mInBuf;        ///< input sample* ptr
    SampleBuffer mSampBuf;      ///< temp sample buf ptr
    fftwf_complex *mSpectBuf;   ///< complex spectrum
    fftwf_plan mPlan;           ///< FFTW plan object
};

#endif

//
// FFTReal-wrapper concrete subclass
//

#ifdef USE_FFTREAL

class FFTR_Wrapper : public Abst_FFT_W {
public:
    FFTR_Wrapper(unsigned size, CSL_FFTType type = CSL_FFT_REAL, CSL_FFTDir forward = CSL_FFT_FORWARD);
    ~FFTR_Wrapper();
                                /// run the transform between in and out
    void nextBuffer(Buffer & in, Buffer & out) throw (CException);

private:        
    SampleBuffer mTempBuf;      ///< temp sample buf ptr
    FFTReal mFFT;               ///< FFTReal object
};

#endif

//
// KISS_FFT-wrapper concrete subclass (untested)
//

#ifdef USE_KISSFFT

class KISSFFT_Wrapper : public Abst_FFT_W {
public:
    KISSFFT_Wrapper(unsigned size, CSL_FFTType type = CSL_FFT_REAL, CSL_FFTDir forward = CSL_FFT_FORWARD);
    ~KISSFFT_Wrapper();
                                /// run the transform between in and out
    void nextBuffer(Buffer & in, Buffer & out) throw (CException);

private:        
    SampleBuffer mTempBuf;      ///< temp sample buf ptr
    kiss_fft_cfg mFFT;          ///< KISS FFT config object pointer
    SampleComplexVector inBuf, outBuf;
};

#endif

}

#endif