annotate constant-q-cpp/src/dsp/SincWindow.cpp @ 372:af71cbdab621 tip

Update bqvec code

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
/*
    Constant-Q library
    Copyright (c) 2013-2014 Queen Mary, University of London

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    obtaining a copy of this software and associated documentation
    files (the "Software"), to deal in the Software without
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    modify, merge, publish, distribute, sublicense, and/or sell copies
    of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

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    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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    Except as contained in this notice, the names of the Centre for
    Digital Music; Queen Mary, University of London; and Chris Cannam
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*/

#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);
	}
    }
}