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/*******************************************************************************
* Copyright 2009-2016 Jörg Müller
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/
#include "fx/IIRFilterReader.h"
AUD_NAMESPACE_BEGIN
IIRFilterReader::IIRFilterReader(std::shared_ptr<IReader> reader, const std::vector<float>& b, const std::vector<float>& a) :
BaseIIRFilterReader(reader, b.size(), a.size()), m_a(a), m_b(b)
{
if(m_a.empty() == false)
{
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 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;
}
void IIRFilterReader::setCoefficients(const std::vector<float>& b, const std::vector<float>& a)
{
setLengths(b.size(), a.size());
m_a = a;
m_b = b;
}
AUD_NAMESPACE_END
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