#pragma once
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#include <cmath>
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#include <EffectProcessorBase.h>
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#define PI 3.14159265358979323846
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/**
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* IIR Filter Class
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*
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*/
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template <typename SampleType>
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class IIRFilter : public EffectProcessorBase<SampleType>
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{
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public:
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/**
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* @brief Constructor
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*/
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IIRFilter();
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/**
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* @brief Destructor
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*/
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~IIRFilter();
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/**
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* @brief Prepares object for playback
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*
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* @param sampleRate Current sampling rate
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*/
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void prepare(SampleType sampleRate) override;
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/**
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* @brief Processes a single sample
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*
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* @param input Input sample
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*/
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SampleType processSample(SampleType input) override;
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/**
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* @brief Processes a memory block that holds audio samples
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*
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* @param data Memory block start pointer
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* @param startSample Sample index to start processing from
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* @param endSample Number of samples to process
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*/
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void process(SampleType* data, int startSample, int endSample) override;
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/**
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* @brief Sets filter cutoff frequency
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*
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* @param newValue New cutoff frequency value
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*
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* When the filter mode is set to Parametric it sets the center frequency instead.
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*/
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void setCutoff(SampleType newValue);
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/**
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* @brief Sets the filter type
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*
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* @param filterType Filter type index
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*/
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void setFilterType(int filterType);
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/**
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* @brief Sets the filter quality factor
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*
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* @param newValue New filter quality factor
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*/
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void setQ(SampleType newValue);
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/**
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* @brief Sets the amount of boost/attenuation of the parametric mode
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*
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* @param newValue New boost/attention value in decibels
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*/
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void setGain(SampleType newValue);
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/**
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* @brief Returns the cutoff/center frequency of the filter
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*/
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SampleType getCutoff();
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/**
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* @brief Returns the quality factor of the filter
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*/
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SampleType getQ();
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/**
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* @brief Returns the boost/cut value of the parametric filter mode
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*/
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SampleType getGain();
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/**
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* @brief Returns the filter type index
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*/
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int getFilterType();
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enum FilterTypes
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{
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LPF = 0, // Low Pass Fitler
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HPF, // High Pass Filter
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Parametric,
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};
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private:
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SampleType a0, a1, a2, b1, b2, c0, d0, r, C;
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// Paremetric EQ Filter Variables
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SampleType K, V0, e0, D0, alpha, beta, gamma, delta, heta;
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SampleType theta_c, u, zeta;
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// Previous in/out values
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SampleType xn_1 = 0, xn_2 = 0, yn_1 = 0, yn_2 = 0;
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// User Parameters
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SampleType fc {500.0}, Q {1.0}, notchGain {0.0};
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int filterType {FilterTypes::LPF};
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void calculateCoeffs();
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};
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