#include <flext.h>
 
#if !defined(FLEXT_VERSION) || (FLEXT_VERSION < 401)
#error You need at least flext version 0.4.1
#endif


// A flext dsp external ("tilde object") inherits from the class flext_dsp 
class yin: 
	public flext_dsp
{
	// Each external that is written in C++ needs to use #defines 
	// from flbase.h
	// 
	// The define
	// 
	// FLEXT_HEADER(NEW_CLASS, PARENT_CLASS)
	// 
	// should be somewhere in your dsp file.
	// A good place is here:
	
	FLEXT_HEADER(yin, flext_dsp)

	public:
	       yin()
		{
			// The constructor of your class is responsible for
			// setting up inlets and outlets and for registering
			// inlet-methods:
			// The descriptions of the inlets and outlets are output
			// via the Max/MSP assist method (when mousing over them in edit mode).
			// PD will hopefully provide such a feature as well soon

			AddInSignal("audio in");       // audio in
			AddOutSignal("fundamental freq out");     // fundamental freq out 
			
			// We're done constructing:
			post("yin~ fundamental frequency estimator");
			
		} // end of constructor
		
	
	protected:
		// here we declare the virtual DSP function
		virtual void m_signal(int n, float *const *in, float *const *out);
        
	private:
                void ACF(const float* ins, int n, float* r);
                void diff(const float* ins, float* r, int n, float* difference);
                void cumnorm(float* difference, int n, float* d_primes);
                float get_max_period(float* d_primes, int n);

}; // end of class declaration for yin

#include "yin_helpers.cpp"

// Before we can run our yin-class in PD, the object has to be registered as a
// PD object. Otherwise it would be a simple C++-class, and what good would
// that be for?  Registering is made easy with the FLEXT_NEW_* macros defined
// in flext.h. For tilde objects without arguments call:

FLEXT_NEW_DSP("yin~", yin)

// Now we define our DSP function. It gets this arguments:
// 
// int n: length of signal vector. Loop over this for your signal processing.
// float *const *in, float *const *out: 
//          These are arrays of the signals in the objects signal inlets rsp.
//          oulets. We come to that later inside the function.

  void yin::m_signal(int n, float *const *in, float *const *out)
{
        //declare local variables
	const float *ins = in[0];
	float *outs = out[0];
	float f_zero;
	float r[n];
	float difference[n];
	float d_primes[n];
	float max_period;

	//calculate autocorrelation
	ACF(ins, n/2, r);

	//calculate difference from autocorrelation
	diff(ins, r, n/2, difference);

	//calculate cumulative norm
	cumnorm(difference, n/2, d_primes);
  
	//convert max period to frequency
	max_period = get_max_period(d_primes, n/2);
	
	if (max_period == 0) f_zero = 0;
	else f_zero = Samplerate()/max_period;

	for (int i=0; i<n; i++) outs[i] = f_zero;

	

}  // end m_signal