juce_audio_basics/utilities/juce_IIRFilter.h

/*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.
 
   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.
 
  ==============================================================================
*/
 
namespace juce
{
 
class IIRFilter;
 
//==============================================================================
class JUCE_API  IIRCoefficients
{
public:
    //==============================================================================
    IIRCoefficients() noexcept;

    IIRCoefficients (double c1, double c2, double c3,
                     double c4, double c5, double c6) noexcept;

    IIRCoefficients (const IIRCoefficients&) noexcept;
    IIRCoefficients& operator= (const IIRCoefficients&) noexcept;
    ~IIRCoefficients() noexcept;
 
    //==============================================================================
    static IIRCoefficients makeLowPass (double sampleRate,
                                        double frequency) noexcept;

    static IIRCoefficients makeLowPass (double sampleRate,
                                        double frequency,
                                        double Q) noexcept;
 
    //==============================================================================
    static IIRCoefficients makeHighPass (double sampleRate,
                                         double frequency) noexcept;

    static IIRCoefficients makeHighPass (double sampleRate,
                                         double frequency,
                                         double Q) noexcept;
 
    //==============================================================================
    static IIRCoefficients makeBandPass (double sampleRate, double frequency) noexcept;

    static IIRCoefficients makeBandPass (double sampleRate,
                                         double frequency,
                                         double Q) noexcept;
 
    //==============================================================================
    static IIRCoefficients makeNotchFilter (double sampleRate, double frequency) noexcept;

    static IIRCoefficients makeNotchFilter (double sampleRate,
                                            double frequency,
                                            double Q) noexcept;
 
    //==============================================================================
    static IIRCoefficients makeAllPass (double sampleRate, double frequency) noexcept;

    static IIRCoefficients makeAllPass (double sampleRate,
                                        double frequency,
                                        double Q) noexcept;
 
    //==============================================================================
    static IIRCoefficients makeLowShelf (double sampleRate,
                                         double cutOffFrequency,
                                         double Q,
                                         float gainFactor) noexcept;

    static IIRCoefficients makeHighShelf (double sampleRate,
                                          double cutOffFrequency,
                                          double Q,
                                          float gainFactor) noexcept;

    static IIRCoefficients makePeakFilter (double sampleRate,
                                           double centreFrequency,
                                           double Q,
                                           float gainFactor) noexcept;
 
    //==============================================================================
    float coefficients[5];
};
 
//==============================================================================
template <typename Mutex>
class JUCE_API  IIRFilterBase
{
public:
    //==============================================================================
    IIRFilterBase() noexcept;

    IIRFilterBase (const IIRFilterBase&) noexcept;
 
    //==============================================================================
    void makeInactive() noexcept;

    void setCoefficients (const IIRCoefficients& newCoefficients) noexcept;

    IIRCoefficients getCoefficients() const noexcept    { return coefficients; }
 
    //==============================================================================
    void reset() noexcept;

    void processSamples (float* samples, int numSamples) noexcept;

    float processSingleSampleRaw (float sample) noexcept;
 
protected:
    //==============================================================================
    Mutex processLock;
    IIRCoefficients coefficients;
    float v1 = 0, v2 = 0;
    bool active = false;
 
    // The exact meaning of an assignment operator would be ambiguous since the filters are
    // stateful. If you want to copy the coefficients, then just use setCoefficients().
    IIRFilter& operator= (const IIRFilter&) = delete;
 
    JUCE_LEAK_DETECTOR (IIRFilter)
};

class IIRFilter : public IIRFilterBase<SpinLock>
{
public:
    using IIRFilterBase::IIRFilterBase;
};

class SingleThreadedIIRFilter : public IIRFilterBase<DummyCriticalSection>
{
public:
    using IIRFilterBase::IIRFilterBase;
};
 
} // namespace juce