FFTReal.h

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/*****************************************************************************
*                                                                            *
*       DIGITAL SIGNAL PROCESSING TOOLS                                      *
*       Version 1.01, 1999/11/07                                             *
*       (c) 1999 - Laurent de Soras                                          *
*                                                                            *
*       FFTReal.h                                                            *
*       Fourier transformation of real number arrays.                        *
*       Portable ISO C++                                                     *
*                                                                            *
*****************************************************************************/

#if defined (FFTReal_CURRENT_HEADER)
    #error Recursive inclusion of FFTReal header file.
#endif
#define FFTReal_CURRENT_HEADER

#if ! defined (FFTReal_HEADER_INCLUDED)
#define FFTReal_HEADER_INCLUDED

#if defined (_MSC_VER)
#pragma pack (push, 8)
#endif  // _MSC_VER

class FFTReal {

/*\\\ PUBLIC \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/

public:
    /* Change this typedef to use a different floating point type in your FFTs
        (i.e. float, double or long double). */
    typedef float   flt_t;

    explicit            FFTReal (const long length);
                        ~FFTReal ();
    void                do_fft (flt_t f [], const flt_t x []) const;
    void                do_ifft (const flt_t f [], flt_t x []) const;
    void                rescale (flt_t x []) const;

/*\\\ PRIVATE \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/

private:

    /* Bit-reversed look-up table nested class */
    class BitReversedLUT {
    public:
        explicit            BitReversedLUT (const int nbr_bits);
                            ~BitReversedLUT ();
        const long * get_ptr () const {
            return (_ptr);
        }
    private:
        long *          _ptr;
    };

    /* Trigonometric look-up table nested class */
    class   TrigoLUT {
    public:
        explicit            TrigoLUT (const int nbr_bits);
                            ~TrigoLUT ();
        const flt_t * get_ptr (const int level) const {
            return (_ptr + (1L << (level - 1)) - 4);
        };
    private:
        flt_t   *           _ptr;
    };

    const BitReversedLUT    _bit_rev_lut;
    const TrigoLUT  _trigo_lut;
    const flt_t     _sqrt2_2;
    const long      _length;
    const int       _nbr_bits;
    flt_t *         _buffer_ptr;

/*\\\ FORBIDDEN MEMBER FUNCTIONS \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/

private:
                        FFTReal (const FFTReal &other);
    const FFTReal&  operator = (const FFTReal &other);
    int             operator == (const FFTReal &other);
    int             operator != (const FFTReal &other);
};

#if defined (_MSC_VER)
#pragma pack (pop)
#endif  // _MSC_VER

#endif  // FFTReal_HEADER_INCLUDED

#undef FFTReal_CURRENT_HEADER

/*****************************************************************************

    LEGAL

    Source code may be freely used for any purpose, including commercial
    applications. Programs must display in their "About" dialog-box (or
    documentation) a text telling they use these routines by Laurent de Soras.
    Modified source code can be distributed, but modifications must be clearly
    indicated.

    CONTACT

    Laurent de Soras
    92 avenue Albert 1er
    92500 Rueil-Malmaison
    France

    ldesoras@club-internet.fr

*****************************************************************************/