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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.
******************************************************************************/
#pragma once
/**
* @file BaseIIRFilterReader.h
* @ingroup fx
* The BaseIIRFilterReader class.
*/
#include "fx/EffectReader.h"
AUD_NAMESPACE_BEGIN
/**
* This class is a base class for infinite impulse response filters.
*/
class AUD_API BaseIIRFilterReader : public EffectReader
{
private:
/**
* Specs.
*/
Specs m_specs;
/**
* Length of input samples needed.
*/
int m_xlen;
/**
* Length of output samples needed.
*/
int m_ylen;
/**
* The last in samples array.
*/
sample_t* m_x;
/**
* The last out samples array.
*/
sample_t* m_y;
/**
* Position of the current input sample in the input array.
*/
int m_xpos;
/**
* Position of the current output sample in the output array.
*/
int m_ypos;
/**
* Current channel.
*/
int m_channel;
// delete copy constructor and operator=
BaseIIRFilterReader(const BaseIIRFilterReader&) = delete;
BaseIIRFilterReader& operator=(const BaseIIRFilterReader&) = delete;
protected:
/**
* Creates a new base IIR filter reader.
* \param reader The reader to read from.
* \param in The count of past input samples needed.
* \param out The count of past output samples needed.
*/
BaseIIRFilterReader(std::shared_ptr<IReader> reader, int in, int out);
/**
* Sets the length for the required input and output samples of the IIR filter.
* @param in The amount of past input samples needed, including the current one.
* @param out The amount of past output samples needed.
*/
void setLengths(int in, int out);
public:
/**
* Retrieves the last input samples.
* \param pos The position, valid are 0 (current) or negative values.
* \return The sample value.
*/
inline sample_t x(int pos)
{
return m_x[(m_xpos + pos + m_xlen) % m_xlen * m_specs.channels + m_channel];
}
/**
* Retrieves the last output samples.
* \param pos The position, valid are negative values.
* \return The sample value.
*/
inline sample_t y(int pos)
{
return m_y[(m_ypos + pos + m_ylen) % m_ylen * m_specs.channels + m_channel];
}
virtual ~BaseIIRFilterReader();
virtual void read(int& length, bool& eos, sample_t* buffer);
/**
* Runs the filtering function.
* \return The current output sample value.
*/
virtual sample_t filter()=0;
/**
* Notifies the filter about a sample rate change.
* \param rate The new sample rate.
*/
virtual void sampleRateChanged(SampleRate rate);
};
AUD_NAMESPACE_END
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