Iir.h

#ifndef STK_IIR_H
#define STK_IIR_H
 
#include "Filter.h"
 
namespace stk {
 
/***************************************************/
/***************************************************/
 
class Iir : public Filter
{
public:
  Iir( void );
 
 
  Iir( std::vector<StkFloat> &bCoefficients, std::vector<StkFloat> &aCoefficients );
 
  ~Iir( void );
 
 
  void setCoefficients( std::vector<StkFloat> &bCoefficients, std::vector<StkFloat> &aCoefficients, bool clearState = false );
 
 
  void setNumerator( std::vector<StkFloat> &bCoefficients, bool clearState = false );
 
 
  void setDenominator( std::vector<StkFloat> &aCoefficients, bool clearState = false );
 
  StkFloat lastOut( void ) const { return lastFrame_[0]; };
 
  StkFloat tick( StkFloat input );
 
 
  StkFrames& tick( StkFrames& frames, unsigned int channel = 0 );
 
 
  StkFrames& tick( StkFrames& iFrames, StkFrames &oFrames, unsigned int iChannel = 0, unsigned int oChannel = 0 );
 
protected:
 
};
 
inline StkFloat Iir :: tick( StkFloat input )
{
  size_t i;
 
  outputs_[0] = 0.0;
  inputs_[0] = gain_ * input;
  for ( i=b_.size()-1; i>0; i-- ) {
    outputs_[0] += b_[i] * inputs_[i];
    inputs_[i] = inputs_[i-1];
  }
  outputs_[0] += b_[0] * inputs_[0];
 
  for ( i=a_.size()-1; i>0; i-- ) {
    outputs_[0] += -a_[i] * outputs_[i];
    outputs_[i] = outputs_[i-1];
  }
 
  lastFrame_[0] = outputs_[0];
  return lastFrame_[0];
}
 
inline StkFrames& Iir :: tick( StkFrames& frames, unsigned int channel )
{
#if defined(_STK_DEBUG_)
  if ( channel >= frames.channels() ) {
    oStream_ << "Iir::tick(): channel and StkFrames arguments are incompatible!";
    handleError( StkError::FUNCTION_ARGUMENT );
  }
#endif
 
  StkFloat *samples = &frames[channel];
  size_t i;
  unsigned int hop = frames.channels();
  for ( unsigned int j=0; j<frames.frames(); j++, samples += hop ) {
    outputs_[0] = 0.0;
    inputs_[0] = gain_ * *samples;
    for ( i=b_.size()-1; i>0; i-- ) {
      outputs_[0] += b_[i] * inputs_[i];
      inputs_[i] = inputs_[i-1];
    }
    outputs_[0] += b_[0] * inputs_[0];
 
    for ( i=a_.size()-1; i>0; i-- ) {
      outputs_[0] += -a_[i] * outputs_[i];
      outputs_[i] = outputs_[i-1];
    }
 
    *samples = outputs_[0];
  }
 
  lastFrame_[0] = *(samples-hop);
  return frames;
}
 
inline StkFrames& Iir :: tick( StkFrames& iFrames, StkFrames& oFrames, unsigned int iChannel, unsigned int oChannel )
{
#if defined(_STK_DEBUG_)
  if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
    oStream_ << "Iir::tick(): channel and StkFrames arguments are incompatible!";
    handleError( StkError::FUNCTION_ARGUMENT );
  }
#endif
 
  StkFloat *iSamples = &iFrames[iChannel];
  StkFloat *oSamples = &oFrames[oChannel];
  size_t i;
  unsigned int iHop = iFrames.channels(), oHop = oFrames.channels();
  for ( unsigned int j=0; j<iFrames.frames(); j++, iSamples += iHop, oSamples += oHop ) {
    outputs_[0] = 0.0;
    inputs_[0] = gain_ * *iSamples;
    for ( i=b_.size()-1; i>0; i-- ) {
      outputs_[0] += b_[i] * inputs_[i];
      inputs_[i] = inputs_[i-1];
    }
    outputs_[0] += b_[0] * inputs_[0];
 
    for ( i=a_.size()-1; i>0; i-- ) {
      outputs_[0] += -a_[i] * outputs_[i];
      outputs_[i] = outputs_[i-1];
    }
 
    *oSamples = outputs_[0];
  }
 
  lastFrame_[0] = *(oSamples-oHop);
  return iFrames;
}
 
} // stk namespace
 
#endif