etlegacy-libs/openal/common/alcomplex.h

#ifndef ALCOMPLEX_H
#define ALCOMPLEX_H

#include "AL/al.h"


#ifdef __cplusplus
extern "C" {
#endif

typedef struct ALcomplex {
    ALdouble Real;
    ALdouble Imag;
} ALcomplex;

/** Addition of two complex numbers. */
inline ALcomplex complex_add(ALcomplex a, ALcomplex b)
{
    ALcomplex result;

    result.Real = a.Real + b.Real;
    result.Imag = a.Imag + b.Imag;

    return result;
}

/** Subtraction of two complex numbers. */
inline ALcomplex complex_sub(ALcomplex a, ALcomplex b)
{
    ALcomplex result;

    result.Real = a.Real - b.Real;
    result.Imag = a.Imag - b.Imag;

    return result;
}

/** Multiplication of two complex numbers. */
inline ALcomplex complex_mult(ALcomplex a, ALcomplex b)
{
    ALcomplex result;

    result.Real = a.Real*b.Real - a.Imag*b.Imag;
    result.Imag = a.Imag*b.Real + a.Real*b.Imag;

    return result;
}

/**
 * Iterative implementation of 2-radix FFT (In-place algorithm). Sign = -1 is
 * FFT and 1 is iFFT (inverse). Fills FFTBuffer[0...FFTSize-1] with the
 * Discrete Fourier Transform (DFT) of the time domain data stored in
 * FFTBuffer[0...FFTSize-1]. FFTBuffer is an array of complex numbers, FFTSize
 * MUST BE power of two.
 */
void complex_fft(ALcomplex *FFTBuffer, ALsizei FFTSize, ALdouble Sign);

/**
 * Calculate the complex helical sequence (discrete-time analytical signal) of
 * the given input using the discrete Hilbert transform (In-place algorithm).
 * Fills Buffer[0...size-1] with the discrete-time analytical signal stored in
 * Buffer[0...size-1]. Buffer is an array of complex numbers, size MUST BE
 * power of two.
 */
void complex_hilbert(ALcomplex *Buffer, ALsizei size);

#ifdef __cplusplus
} // extern "C"
#endif

#endif /* ALCOMPLEX_H */