#include "block.h"

#include "fir.h"
#include "window.h"
#include "silowpass.h"

class FIRLowpassHamming :
      public Block
{
  private:
    InPort < double > * in;
    OutPort < double > * out;

    Parameter < long > * samples;
    Parameter < double > * fc;

    Fir < double > fir;

  public:
    FIRLowpassHamming(const Blockopt & blockopt) : Block(blockopt)
    {}


    void makeParameters()
    {
      samples = new Parameter < long > (this, "samples", 10);
      fc = new Parameter < double > (this, "fc", 0.5);
    }


    void makeIOPorts()
    {
      in = new InPort < double > (this, "in", 1);
      out = new OutPort < double > (this, "out", 1);
    }


    void initialize()
    {
      long fulllength = samples->value();
      long halflength = fulllength / 2;

      double firprototype[fulllength];

      if ( halflength*2 == fulllength )
      {
        // even no.of samples ( group delay is NOT an integer )
        for (long k = 0; k < halflength; k++)
        {
          firprototype[halflength + k] =
            firprototype[halflength - 1 - k] =
              siLowpass(double(k + 0.5), fc->value());
        }
      }
      else
      {
        // odd no.of samples ( group delay IS an integer )
        for (long k = 0; k <= halflength; k++)
        {
          firprototype[halflength + k] =
            firprototype[halflength - k] =
              siLowpass(double(k), fc->value());
        }
      }


      // multiply with Hamming window
      for (long k = 0;k < fulllength;k++)
      {
        firprototype[k] *= hamming(fulllength, k);
      }


      // normalize to 0dB at frequency 0
      double sum = 0.;
      for (long k = 0; k < fulllength; k++)
        sum += firprototype[k];
      for (long k = 0; k < fulllength; k++)
        firprototype[k] /= sum;


      fir.create(fulllength, firprototype);
    }


    void go()
    {
      out->write(fir.filter(in->read()));
    }
};


PUBLISH(FIRLowpassHamming);