cannam@0: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
cannam@0: 
cannam@0: /*
cannam@0:     QM DSP Library
cannam@0: 
cannam@0:     Centre for Digital Music, Queen Mary, University of London.
cannam@0: */
cannam@0: 
cannam@0: #ifndef FFT_H
cannam@0: #define FFT_H
cannam@0: 
cannam@0: class FFT  
cannam@0: {
cannam@0: public:
Chris@114:     /**
Chris@114:      * Construct an FFT object to carry out complex-to-complex
Chris@114:      * transforms of size nsamples. nsamples must be a power of two in
Chris@114:      * this implementation.
Chris@114:      */
Chris@114:     FFT(int nsamples);
cannam@64:     ~FFT();
cannam@0: 
Chris@114:     /**
Chris@114:      * Carry out a forward or inverse transform (depending on the
Chris@114:      * value of inverse) of size nsamples, where nsamples is the value
Chris@114:      * provided to the constructor above.
Chris@114:      *
Chris@114:      * realIn and (where present) imagIn should contain nsamples each,
Chris@114:      * and realOut and imagOut should point to enough space to receive
Chris@114:      * nsamples each.
Chris@114:      *
Chris@114:      * imagIn may be NULL if the signal is real, but the other
Chris@114:      * pointers must be valid.
Chris@114:      *
Chris@114:      * The inverse transform is scaled by 1/nsamples.
Chris@114:      */
cannam@64:     void process(bool inverse,
cannam@64:                  const double *realIn, const double *imagIn,
cannam@64:                  double *realOut, double *imagOut);
cannam@64:     
cannam@64: private:
Chris@114:     int m_n;
cannam@0: };
cannam@0: 
cannam@64: class FFTReal
cannam@64: {
cannam@64: public:
Chris@114:     /**
Chris@114:      * Construct an FFT object to carry out real-to-complex transforms
Chris@114:      * of size nsamples. nsamples must be a power of two in this
Chris@114:      * implementation.
Chris@114:      */
Chris@114:     FFTReal(int nsamples);
cannam@64:     ~FFTReal();
cannam@64: 
Chris@114:     /**
Chris@114:      * Carry out a forward real-to-complex transform of size nsamples,
Chris@114:      * where nsamples is the value provided to the constructor above.
Chris@114:      *
Chris@114:      * realIn, realOut, and imagOut must point to (enough space for)
Chris@114:      * nsamples values. For consistency with the FFT class above, and
Chris@114:      * compatibility with existing code, the conjugate half of the
Chris@114:      * output is returned even though it is redundant.
Chris@114:      */
Chris@114:     void forward(const double *realIn,
cannam@64:                  double *realOut, double *imagOut);
cannam@64: 
Chris@114:     /**
Chris@114:      * Carry out an inverse real transform (i.e. complex-to-real) of
Chris@114:      * size nsamples, where nsamples is the value provided to the
Chris@114:      * constructor above.
Chris@114:      *
Chris@114:      * realIn and imagIn should point to at least nsamples/2+1 values;
Chris@114:      * if more are provided, only the first nsamples/2+1 values of
Chris@114:      * each will be used (the conjugate half will always be deduced
Chris@114:      * from the first nsamples/2+1 rather than being read from the
Chris@114:      * input data).  realOut should point to enough space to receive
Chris@114:      * nsamples values.
Chris@114:      *
Chris@114:      * The inverse transform is scaled by 1/nsamples.
Chris@114:      */
Chris@114:     void inverse(const double *realIn, const double *imagIn,
Chris@114:                  double *realOut);
Chris@114: 
cannam@64: private:
Chris@114:     int m_n;
Chris@114:     FFT *m_fft;
Chris@114:     double *m_r;
Chris@114:     double *m_i;
Chris@114:     double *m_discard;
cannam@64: };    
cannam@64: 
cannam@0: #endif