C:/Work/specialnumbers_svn/NumberLib/NumbersLib/XYResponseCurve.h

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#ifndef _XY_RESPONSE_CURVE_H
#define _XY_RESPONSE_CURVE_H

#include "AbstractFunction.h"

namespace luma
{
namespace numbers
{
template<class T, unsigned int n>
class XYResponseCurve: public AbstractFunction<T>
{
public:
   XYResponseCurve(T inputSamples[n], T outputSamples[n]);

   T operator()(const T input) const;
   
   void makeInverse();

   unsigned int findInputIndex(const T input) const;

private:
   T mInputSamples[n];
   T mOutputSamples[n];
   
};

template<class T, unsigned int n> 
XYResponseCurve<T, n>::XYResponseCurve(T inputSamples[n], T outputSamples[n])
{
   for(unsigned i = 0; i < n; i++)
   {
      mInputSamples[i] = inputSamples[i];
      mOutputSamples[i] = outputSamples[i];
   }
}

template<class T, unsigned int n> 
T XYResponseCurve<T, n>::operator()(const T input) const
{
   if (input <= mInputSamples[0])
   {
      return mOutputSamples[0];
   }

   if (input >= mInputSamples[n - 1])
   {
      return mOutputSamples[n - 1];
   }

   unsigned int index = findInputIndex(input);


   T x1 = mInputSamples[index + 1];
   T x0 = mInputSamples[index];

   T tau = (input - x0) / (x1 - x0);
   T y1 = mOutputSamples[index + 1];
   T y0 = mOutputSamples[index];
   return (y1 - y0) * tau + y0;
}

template<class T, unsigned int n> 
unsigned int XYResponseCurve<T, n>::findInputIndex(const T input) const
{
   unsigned int min = 0;
   unsigned int max = n;
   unsigned int mid;

   while (max > min + 1)
   {
      mid = (max + min) / 2 ;
      //printf("mmm: %d %d %d\n", min, mid, max);

      if(input < mInputSamples[mid])
      {
         max = mid;
      }
      else
      {
         min = mid;
      }  
   }

   return min;
}
template<class T, unsigned int n> 
void XYResponseCurve<T, n>::makeInverse()
{
   T tmp;

   for (unsigned i = 0; i < n; i++)
   {
      tmp = mInputSamples[i];
      mInputSamples[i] = mOutputSamples[i];
      mOutputSamples[i] = tmp;
   }
}


}
}

#endif //_XYRESPONSE_CURVE_H

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