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/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/
**
** This file is part of the demonstration applications of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation and
** appearing in the file LICENSE.LGPL included in the packaging of this
** file. Please review the following information to ensure the GNU Lesser
** General Public License version 2.1 requirements will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "fastfouriertransformer.h"
#include "math.h"
#define STIN inline
#define __STATIC
#include "fftpack.c"
// called by __ogg_fdrffti
__STATIC void drfti1(int n, float *wa, int *ifac);
void __ogg_fdrffti(int n, float *wsave, int *ifac);
void __ogg_fdcosqi(int n, float *wsave, int *ifac);
// called by drftf1
STIN void dradf2(int ido,int l1,float *cc,float *ch,float *wa1);
// called by drftf1
STIN void dradf4(int ido,int l1,float *cc,float *ch,float *wa1,
float *wa2,float *wa3);
// called by drftf1
STIN void dradfg(int ido,int ip,int l1,int idl1,float *cc,float *c1,
float *c2,float *ch,float *ch2,float *wa);
// called by drftf1
STIN void drftf1(int n,float *c,float *ch,float *wa,int *ifac);
void __ogg_fdrfftf(int n,float *r,float *wsave,int *ifac);
STIN void dcsqf1(int n,float *x,float *w,float *xh,int *ifac);
void __ogg_fdcosqf(int n,float *x,float *wsave,int *ifac);
STIN void dradb2(int ido,int l1,float *cc,float *ch,float *wa1);
STIN void dradb3(int ido,int l1,float *cc,float *ch,float *wa1,
float *wa2);
STIN void dradb4(int ido,int l1,float *cc,float *ch,float *wa1,
float *wa2,float *wa3);
STIN void dradbg(int ido,int ip,int l1,int idl1,float *cc,float *c1,
float *c2,float *ch,float *ch2,float *wa);
STIN void drftb1(int n, float *c, float *ch, float *wa, int *ifac);
void __ogg_fdrfftb(int n, float *r, float *wsave, int *ifac);
STIN void dcsqb1(int n,float *x,float *w,float *xh,int *ifac);
void __ogg_fdcosqb(int n,float *x,float *wsave,int *ifac);
FastFourierTransformer::FastFourierTransformer(QObject *parent) :
QObject(parent),
m_waveFloat(0),
m_workingArray(0),
m_ifac(0),
m_last_n(-1)
{
}
FastFourierTransformer::~FastFourierTransformer()
{
if (m_waveFloat != 0) {
delete [] m_waveFloat;
}
if (m_workingArray != 0) {
delete [] m_workingArray;
}
if (m_ifac != 0) {
delete [] m_ifac;
}
}
/**
* Prepares the arrays to be of length n.
*/
void FastFourierTransformer::reserve(int n)
{
Q_ASSERT(n>0);
if (m_waveFloat != 0) {
delete [] m_waveFloat;
}
if (m_workingArray != 0) {
delete [] m_workingArray;
}
if (m_ifac != 0) {
delete [] m_ifac;
}
m_workingArray = new float[2*n+15];
m_waveFloat = new float[n];
m_ifac = new int[n];
__ogg_fdrffti(n, m_workingArray, m_ifac);
m_last_n = n;
}
/**
* Calculates the Fast Fourier Transformation (FFT).
*/
void FastFourierTransformer::calculateFFT(QList<qint16> wave)
{
const int n = wave.size();
if (m_last_n != n) {
reserve(n);
}
for (int i = 0; i < n; i++) {
m_waveFloat[i] = (float) wave.at(i);
}
__ogg_fdrfftf(n, m_waveFloat, m_workingArray, m_ifac);
}
/**
* Returns the index which corresponds to the maximum density
* of the FFT.
*/
int FastFourierTransformer::getMaximumDensityIndex()
{
const int halfN = m_last_n / 2;
float maxDensity = 0;
int maxDensityIndex = 0;
float densitySquared = 0.f;
for (int k = 1; k < halfN; k++) {
// Here, we calculate the frequency k/N.
// k=1, the wave oscillation time is N, and the frequency
// is 1/sample.
// k=2, the wave oscillation time is N/2, and the frequency
// is 2/sample.
// k=3, the wave oscillation time is N/3, and the frequency
// is 3/sample.
// Note, that the documentation is for Fortran, so indexes in the
// documentation does not match.
// The sine and cosine coefficients are obtained thus as follows:
const float cosCoefficient = qAbs(m_waveFloat[2*k-1]);
const float sinCoefficient = qAbs(m_waveFloat[2*k]);
densitySquared = sinCoefficient*sinCoefficient + cosCoefficient*cosCoefficient;
if (densitySquared > maxDensity) {
maxDensity = densitySquared;
maxDensityIndex = k;
}
}
if (m_cutOffForDensitySquared < maxDensity) {
return maxDensityIndex;
}
else {
return -1;
}
}
/**
* Sets the cutoff density.
*/
void FastFourierTransformer::setCutOffForDensity(float cutoff)
{
m_cutOffForDensitySquared = cutoff*cutoff;
}
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