Function NewWindowFunc

libraries/lib-fft/FFT.cpp:368–510

}

void NewWindowFunc(int whichFunction, size_t NumSamplesIn, bool extraSample, float *in)
{
   int NumSamples = (int)NumSamplesIn;
   if (extraSample) {
      wxASSERT(NumSamples > 0);
      --NumSamples;
   }
   wxASSERT(NumSamples > 0);

   switch (whichFunction) {
   default:
      wxFprintf(stderr, "FFT::WindowFunc - Invalid window function: %d\n", whichFunction);
      break;
   case eWinFuncRectangular:
      // Multiply all by 1.0f -- do nothing
      break;

   case eWinFuncBartlett:
   {
      // Bartlett (triangular) window
      const int nPairs = (NumSamples - 1) / 2; // whether even or odd NumSamples, this is correct
      const float denom = NumSamples / 2.0f;
      in[0] = 0.0f;
      for (int ii = 1;
           ii <= nPairs; // Yes, <=
           ++ii) {
         const float value = ii / denom;
         in[ii] *= value;
         in[NumSamples - ii] *= value;
      }
      // When NumSamples is even, in[half] should be multiplied by 1.0, so unchanged
      // When odd, the value of 1.0 is not reached
   }
      break;
   case eWinFuncHamming:
   {
      // Hamming
      const double multiplier = 2 * M_PI / NumSamples;
      static const double coeff0 = 0.54, coeff1 = -0.46;
      for (int ii = 0; ii < NumSamples; ++ii)
         in[ii] *= coeff0 + coeff1 * cos(ii * multiplier);
   }
      break;
   case eWinFuncHann:
   {
      // Hann
      const double multiplier = 2 * M_PI / NumSamples;
      static const double coeff0 = 0.5, coeff1 = -0.5;
      for (int ii = 0; ii < NumSamples; ++ii)
         in[ii] *= coeff0 + coeff1 * cos(ii * multiplier);
   }
      break;
   case eWinFuncBlackman:
   {
      // Blackman
      const double multiplier = 2 * M_PI / NumSamples;
      const double multiplier2 = 2 * multiplier;
      static const double coeff0 = 0.42, coeff1 = -0.5, coeff2 = 0.08;