c@225: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
c@225: 
c@225: /*
c@225:     QM DSP Library
c@225: 
c@225:     Centre for Digital Music, Queen Mary, University of London.
c@225:     This file is based on Don Cross's public domain FFT implementation.
c@225: */
c@225: 
c@225: #include "FFT.h"
c@280: 
c@280: #include "maths/MathUtilities.h"
c@280: 
c@355: #include "kiss_fft.h"
c@355: #include "kiss_fftr.h"
c@355: 
c@225: #include <cmath>
c@225: 
c@280: #include <iostream>
c@280: 
c@355: #include <stdexcept>
c@355: 
c@355: class FFT::D
c@355: {
c@355: public:
c@355:     D(int n) : m_n(n) {
c@355:         m_planf = kiss_fft_alloc(m_n, 0, NULL, NULL);
c@355:         m_plani = kiss_fft_alloc(m_n, 1, NULL, NULL);
c@355:         m_kin = new kiss_fft_cpx[m_n];
c@355:         m_kout = new kiss_fft_cpx[m_n];
c@355:     }
c@355: 
c@355:     ~D() {
c@355:         kiss_fft_free(m_planf);
c@355:         kiss_fft_free(m_plani);
c@355:         delete[] m_kin;
c@355:         delete[] m_kout;
c@355:     }
c@355: 
c@355:     void process(bool inverse,
c@355:                  const double *ri,
c@355:                  const double *ii,
c@355:                  double *ro,
c@355:                  double *io) {
c@355: 
c@355:         for (int i = 0; i < m_n; ++i) {
c@355:             m_kin[i].r = ri[i];
c@355:             m_kin[i].i = (ii ? ii[i] : 0.0);
c@355:         }
c@355: 
c@355:         if (!inverse) {
c@355: 
c@355:             kiss_fft(m_planf, m_kin, m_kout);
c@355: 
c@355:             for (int i = 0; i < m_n; ++i) {
c@355:                 ro[i] = m_kout[i].r;
c@355:                 io[i] = m_kout[i].i;
c@355:             }
c@355: 
c@355:         } else {
c@355: 
c@355:             kiss_fft(m_plani, m_kin, m_kout);
c@355: 
c@355:             double scale = 1.0 / m_n;
c@355: 
c@355:             for (int i = 0; i < m_n; ++i) {
c@355:                 ro[i] = m_kout[i].r * scale;
c@355:                 io[i] = m_kout[i].i * scale;
c@355:             }
c@355:         }
c@355:     }
c@355:     
c@355: private:
c@355:     int m_n;
c@355:     kiss_fft_cfg m_planf;
c@355:     kiss_fft_cfg m_plani;
c@355:     kiss_fft_cpx *m_kin;
c@355:     kiss_fft_cpx *m_kout;
c@355: };        
c@355: 
c@339: FFT::FFT(int n) :
c@355:     m_d(new D(n))
c@225: {
c@225: }
c@225: 
c@225: FFT::~FFT()
c@225: {
c@355:     delete m_d;
c@225: }
c@225: 
c@355: void
c@355: FFT::process(bool inverse,
c@355:              const double *p_lpRealIn, const double *p_lpImagIn,
c@355:              double *p_lpRealOut, double *p_lpImagOut)
c@355: {
c@355:     m_d->process(inverse,
c@355:                  p_lpRealIn, p_lpImagIn,
c@355:                  p_lpRealOut, p_lpImagOut);
c@355: }
c@355:     
c@355: class FFTReal::D
c@355: {
c@355: public:
c@355:     D(int n) : m_n(n) {
c@355:         if (n % 2) {
c@355:             throw std::invalid_argument
c@355:                 ("nsamples must be even in FFTReal constructor");
c@355:         }
c@355:         m_planf = kiss_fftr_alloc(m_n, 0, NULL, NULL);
c@355:         m_plani = kiss_fftr_alloc(m_n, 1, NULL, NULL);
c@355:         m_c = new kiss_fft_cpx[m_n];
c@355:     }
c@355: 
c@355:     ~D() {
c@355:         kiss_fftr_free(m_planf);
c@355:         kiss_fftr_free(m_plani);
c@355:         delete[] m_c;
c@355:     }
c@355: 
c@355:     void forward(const double *ri, double *ro, double *io) {
c@355: 
c@355:         kiss_fftr(m_planf, ri, m_c);
c@355: 
c@355:         for (int i = 0; i <= m_n/2; ++i) {
c@355:             ro[i] = m_c[i].r;
c@355:             io[i] = m_c[i].i;
c@355:         }
c@355: 
c@355:         for (int i = 0; i + 1 < m_n/2; ++i) {
c@355:             ro[m_n - i - 1] =  ro[i + 1];
c@355:             io[m_n - i - 1] = -io[i + 1];
c@355:         }
c@355:     }
c@355: 
c@355:     void inverse(const double *ri, const double *ii, double *ro) {
c@355: 
c@355:         for (int i = 0; i < m_n; ++i) {
c@355:             m_c[i].r = ri[i];
c@355:             m_c[i].i = ii[i];
c@355:         }
c@355:         
c@355:         kiss_fftri(m_plani, m_c, ro);
c@355: 
c@355:         double scale = 1.0 / m_n;
c@355: 
c@355:         for (int i = 0; i < m_n; ++i) {
c@355:             ro[i] *= scale;
c@355:         }
c@355:     }
c@355: 
c@355: private:
c@355:     int m_n;
c@355:     kiss_fftr_cfg m_planf;
c@355:     kiss_fftr_cfg m_plani;
c@355:     kiss_fft_cpx *m_c;
c@355: };
c@355: 
c@339: FFTReal::FFTReal(int n) :
c@355:     m_d(new D(n)) 
c@225: {
c@289: }
c@225: 
c@289: FFTReal::~FFTReal()
c@289: {
c@355:     delete m_d;
c@289: }
c@289: 
c@289: void
c@355: FFTReal::forward(const double *ri, double *ro, double *io)
c@289: {
c@355:     m_d->forward(ri, ro, io);
c@289: }
c@289: 
c@339: void
c@355: FFTReal::inverse(const double *ri, const double *ii, double *ro)
c@339: {
c@355:     m_d->inverse(ri, ii, ro);
c@339: }
c@339: 
c@289: 
c@355: