Twang.h

#ifndef STK_TWANG_H
#define STK_TWANG_H

#include "Stk.h"
#include "DelayA.h"
#include "DelayL.h"
#include "Fir.h"

namespace stk {

/***************************************************/
/***************************************************/

class Twang : public Stk
{
 public:
  Twang( StkFloat lowestFrequency = 50.0 );

  void clear( void );

  void setLowestFrequency( StkFloat frequency );

  void setFrequency( StkFloat frequency );

  void setPluckPosition( StkFloat position );


  void setLoopGain( StkFloat loopGain );


  void setLoopFilter( std::vector<StkFloat> coefficients );

  //const StkFrames& lastFrame( void ) const { return lastFrame_; };

  // StkFloat lastOut( void ) { return lastFrame_[0]; };
  StkFloat lastOut( void ) { return lastOutput_; };

  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:  

  DelayA   delayLine_;
  DelayL   combDelay_;
  Fir      loopFilter_;

  StkFloat lastOutput_;
  StkFloat frequency_;
  StkFloat loopGain_;
  StkFloat pluckPosition_;
};

inline StkFloat Twang :: tick( StkFloat input )
{
  lastOutput_ = delayLine_.tick( input + loopFilter_.tick( delayLine_.lastOut() ) );
  lastOutput_ -= combDelay_.tick( lastOutput_ ); // comb filtering on output
  lastOutput_ *= 0.5;

  return lastOutput_;
}

inline StkFrames& Twang :: tick( StkFrames& frames, unsigned int channel )
{
#if defined(_STK_DEBUG_)
  if ( channel >= frames.channels() ) {
    oStream_ << "Twang::tick(): channel and StkFrames arguments are incompatible!";
    handleError( StkError::FUNCTION_ARGUMENT );
  }
#endif

  StkFloat *samples = &frames[channel];
  unsigned int hop = frames.channels();
  for ( unsigned int i=0; i<frames.frames(); i++, samples += hop )
    *samples = tick( *samples );

  return frames;
}

inline StkFrames& Twang :: tick( StkFrames& iFrames, StkFrames& oFrames, unsigned int iChannel, unsigned int oChannel )
{
#if defined(_STK_DEBUG_)
  if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
    oStream_ << "Twang::tick(): channel and StkFrames arguments are incompatible!";
    handleError( StkError::FUNCTION_ARGUMENT );
  }
#endif

  StkFloat *iSamples = &iFrames[iChannel];
  StkFloat *oSamples = &oFrames[oChannel];
  unsigned int iHop = iFrames.channels(), oHop = oFrames.channels();
  for ( unsigned int i=0; i<iFrames.frames(); i++, iSamples += iHop, oSamples += oHop )
    *oSamples = tick( *iSamples );

  return iFrames;
}

} // stk namespace

#endif