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root / src / portaudio_20161030_catalina_patch / qa / loopback / src / biquad_filter.h @ 164:9fa11135915a

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#ifndef _BIQUADFILTER_H
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#define _BIQUADFILTER_H
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/**


    		
  

  

    
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 *        Unit_BiquadFilter implements a second order IIR filter. 


    		
  

  

    
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 *


    		
  

  

    
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 * @author (C) 2002 Phil Burk, SoftSynth.com, All Rights Reserved


    		
  

  

    
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 */


    		
  

  

    
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#define BIQUAD_MIN_RATIO     (0.000001)


    		
  

  

    
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#define BIQUAD_MIN_Q         (0.00001)


    		
  

  

    
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typedef struct BiquadFilter_s


    		
  

  

    
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{


    		
  

  

    
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    double      xn1;    // storage for delayed signals


    		
  

  

    
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        double      xn2;


    		
  

  

    
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        double      yn1;


    		
  

  

    
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        double      yn2;


    		
  

  

    
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        double      a0;    // coefficients


    		
  

  

    
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        double      a1;


    		
  

  

    
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        double      a2;


    		
  

  

    
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        double      b1;


    		
  

  

    
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        double      b2;


    		
  

  

    
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        double      cos_omega;


    		
  

  

    
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        double      sin_omega;


    		
  

  

    
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        double      alpha;


    		
  

  

    
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} BiquadFilter;


    		
  

  

    
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void BiquadFilter_SetupHighPass( BiquadFilter *filter, double ratio, double Q );


    		
  

  

    
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void BiquadFilter_SetupNotch( BiquadFilter *filter, double ratio, double Q );


    		
  

  

    
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void BiquadFilter_Filter( BiquadFilter *filter, float *inputs, float *outputs, int numSamples );


    		
  

  

    
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#endif