AUD_IIRFilterReader.cpp

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/*
 * $Id: AUD_IIRFilterReader.cpp 35141 2011-02-25 10:21:56Z jesterking $
 *
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * Copyright 2009-2011 Jörg Hermann Müller
 *
 * This file is part of AudaSpace.
 *
 * Audaspace 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.
 *
 * AudaSpace is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Audaspace; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include "AUD_IIRFilterReader.h"

AUD_IIRFilterReader::AUD_IIRFilterReader(AUD_IReader* reader,
                                                                                 std::vector<float> b,
                                                                                 std::vector<float> a) :
        AUD_BaseIIRFilterReader(reader, b.size(), a.size()), m_a(a), m_b(b)
{
        for(int i = 1; i < m_a.size(); i++)
                m_a[i] /= m_a[0];
        for(int i = 0; i < m_b.size(); i++)
                m_b[i] /= m_a[0];
        m_a[0] = 1;
}

sample_t AUD_IIRFilterReader::filter()
{
        sample_t out = 0;

        for(int i = 1; i < m_a.size(); i++)
                out -= y(-i) * m_a[i];
        for(int i = 0; i < m_b.size(); i++)
                out += x(-i) * m_b[i];

        return out;
}