mirror of
https://github.com/thestk/stk
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113 lines
3.4 KiB
C++
113 lines
3.4 KiB
C++
/***************************************************/
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/*! \class Filter
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\brief STK filter class.
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This class implements a generic structure which
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can be used to create a wide range of filters.
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It can function independently or be subclassed
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to provide more specific controls based on a
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particular filter type.
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In particular, this class implements the standard
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difference equation:
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a[0]*y[n] = b[0]*x[n] + ... + b[nb]*x[n-nb] -
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a[1]*y[n-1] - ... - a[na]*y[n-na]
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If a[0] is not equal to 1, the filter coeffcients
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are normalized by a[0].
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The \e gain parameter is applied at the filter
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input and does not affect the coefficient values.
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The default gain value is 1.0. This structure
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results in one extra multiply per computed sample,
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but allows easy control of the overall filter gain.
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by Perry R. Cook and Gary P. Scavone, 1995 - 2002.
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*/
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/***************************************************/
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#if !defined(__FILTER_H)
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#define __FILTER_H
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#include "Stk.h"
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class Filter : public Stk
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{
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public:
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//! Default constructor creates a zero-order pass-through "filter".
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Filter(void);
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//! Overloaded constructor which takes filter coefficients.
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/*!
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An StkError can be thrown if either \e nb or \e na is less than
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one, or if the a[0] coefficient is equal to zero.
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*/
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Filter(int nb, MY_FLOAT *bCoefficients, int na, MY_FLOAT *aCoefficients);
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//! Class destructor.
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virtual ~Filter(void);
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//! Clears all internal states of the filter.
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void clear(void);
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//! Set filter coefficients.
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/*!
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An StkError can be thrown if either \e nb or \e na is less than
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one, or if the a[0] coefficient is equal to zero. If a[0] is not
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equal to 1, the filter coeffcients are normalized by a[0].
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*/
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void setCoefficients(int nb, MY_FLOAT *bCoefficients, int na, MY_FLOAT *aCoefficients);
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//! Set numerator coefficients.
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/*!
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An StkError can be thrown if \e nb is less than one. Any
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previously set denominator coefficients are left unaffected.
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Note that the default constructor sets the single denominator
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coefficient a[0] to 1.0.
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*/
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void setNumerator(int nb, MY_FLOAT *bCoefficients);
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//! Set denominator coefficients.
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/*!
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An StkError can be thrown if \e na is less than one or if the
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a[0] coefficient is equal to zero. Previously set numerator
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coefficients are unaffected unless a[0] is not equal to 1, in
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which case all coeffcients are normalized by a[0]. Note that the
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default constructor sets the single numerator coefficient b[0]
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to 1.0.
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*/
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void setDenominator(int na, MY_FLOAT *aCoefficients);
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//! Set the filter gain.
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/*!
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The gain is applied at the filter input and does not affect the
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coefficient values. The default gain value is 1.0.
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*/
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virtual void setGain(MY_FLOAT theGain);
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//! Return the current filter gain.
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virtual MY_FLOAT getGain(void) const;
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//! Return the last computed output value.
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virtual MY_FLOAT lastOut(void) const;
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//! Input one sample to the filter and return one output.
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virtual MY_FLOAT tick(MY_FLOAT sample);
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//! Input \e vectorSize samples to the filter and return an equal number of outputs in \e vector.
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virtual MY_FLOAT *tick(MY_FLOAT *vector, unsigned int vectorSize);
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protected:
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MY_FLOAT gain;
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int nB;
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int nA;
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MY_FLOAT *b;
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MY_FLOAT *a;
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MY_FLOAT *outputs;
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MY_FLOAT *inputs;
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};
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#endif
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