al_Biquad.hpp

//  Created by Ryan McGee on 5/8/15.
//
//
 
#ifndef __AL_BIQUAD__
#define __AL_BIQUAD__
 
namespace al {
 
/* this holds the data required to update samples thru a filter */
typedef struct {
  double a0, a1, a2, a3, a4;
  double x1, x2, y1, y2;
} BiquadData;
 
/* filter types */
enum BIQUADTYPE {
  BIQUAD_LPF,   /* low pass filter */
  BIQUAD_HPF,   /* High pass filter */
  BIQUAD_BPF,   /* band pass filter */
  BIQUAD_NOTCH, /* Notch Filter */
  BIQUAD_PEQ,   /* Peaking band EQ filter */
  BIQUAD_LSH,   /* Low shelf filter */
  BIQUAD_HSH    /* High shelf filter */
};
 
class BiQuad {
 public:
  BiQuad(BIQUADTYPE _type = BIQUAD_LPF, double _sampleRate = 44100);
  ~BiQuad();
 
  void set(double freq, double bandwidth = 1.9, double dbGain = 0);
  void setSampleRate(double _rate) { mSampleRate = _rate; }
  void processBuffer(float *buffer, int count);
  double operator()(double sample);
 
  void enable(bool on) { enabled = on; }
 
 private:
  BIQUADTYPE mType;
  BiquadData mBD;
  double mSampleRate;
  bool enabled;
};
 
class BiQuadNX {
 public:
  BiQuadNX(int _numFilters = 8, BIQUADTYPE _type = BIQUAD_LPF,
           double _sampleRate = 44100);
  ~BiQuadNX();
 
  void set(double freq, double bandwidth = 0.26, double dbGain = 0);
  void setSampleRate(double _rate);
  void processBuffer(float *buffer, int count);
  double operator()(double sample);
  void enable(bool on);
 
 private:
  int numFilters;
  BiQuad *mFilters;
};
 
}  // namespace al
 
#endif /* defined(__AL_BIQUAD__) */