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livetrax/libs/qm-dsp/base/SincWindow.cpp

46 lines
1.1 KiB
C++

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
/*
QM DSP library
Centre for Digital Music, Queen Mary, University of London.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version. See the file
COPYING included with this distribution for more information.
*/
#include "SincWindow.h"
#include <cmath>
void
SincWindow::init()
{
if (m_length < 1) {
return;
} else if (m_length < 2) {
m_window.push_back(1);
return;
} else {
int n0 = (m_length % 2 == 0 ? m_length/2 : (m_length - 1)/2);
int n1 = (m_length % 2 == 0 ? m_length/2 : (m_length + 1)/2);
double m = 2 * M_PI / m_p;
for (int i = 0; i < n0; ++i) {
double x = ((m_length / 2) - i) * m;
m_window.push_back(sin(x) / x);
}
m_window.push_back(1.0);
for (int i = 1; i < n1; ++i) {
double x = i * m;
m_window.push_back(sin(x) / x);
}
}
}