TTAllpass1b.cpp

Go to the documentation of this file.

/** @file
 *
 * @ingroup dspFilterLib
 *
 * @brief #TTAllpass1b is a first-order building-block allpass filter.
 *
 * @details This allpass filter uses a fixed delay of 2 samples (M=2).
 *
 * @authors Timothy Place, Trond Lossius
 *
 * @copyright Copyright © 2010, Timothy Place @n
 * This code is licensed under the terms of the "New BSD License" @n
 * http://creativecommons.org/licenses/BSD/
 */


#include "TTAllpass1b.h"

#define thisTTClass         TTAllpass1b
#define thisTTClassName     "allpass.1b"
#define thisTTClassTags     "dspFilterLib, audio, processor, filter, allpass"

#ifdef TT_PLATFORM_WIN
#include <Algorithm>
#endif

TT_AUDIO_CONSTRUCTOR,
    mAlpha(0)
{
    TTChannelCount initialMaxNumChannels = arguments;

    addAttribute(Alpha, kTypeFloat64);
    
    addMessage(clear);
    addUpdates(MaxNumChannels);

    setAttributeValue(kTTSym_maxNumChannels,    initialMaxNumChannels);
    setProcessMethod(processAudio);
}


TTAllpass1b::~TTAllpass1b()
{
    ;
}


TTErr TTAllpass1b::updateMaxNumChannels(const TTValue& oldMaxNumChannels, TTValue&)
{
    mX1.resize(mMaxNumChannels);
    mX2.resize(mMaxNumChannels);
    mY1.resize(mMaxNumChannels);
    mY2.resize(mMaxNumChannels);
    clear();
    return kTTErrNone;
}


TTErr TTAllpass1b::clear()
{
    mX1.assign(mMaxNumChannels, 0.0);
    mX2.assign(mMaxNumChannels, 0.0);
    mY2.assign(mMaxNumChannels, 0.0);
    mY1.assign(mMaxNumChannels, 0.0);
    return kTTErrNone;
}


TTErr TTAllpass1b::calculateValue(const TTFloat64& x, TTFloat64& y, TTPtrSizedInt channel)
{
    y = mX2[channel] + mAlpha * (x - mY2[channel]);
    TTZeroDenormal(y);
    mX2[channel] = mX1[channel];
    mY2[channel] = mY1[channel];
    mX1[channel] = x;
    mY1[channel] = y;

    return kTTErrNone;
}


TTErr TTAllpass1b::processAudio(TTAudioSignalArrayPtr inputs, TTAudioSignalArrayPtr outputs)
{
    TT_WRAP_CALCULATE_METHOD(calculateValue);
}