fft.c

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 */


#include "extern.h"

#include <gsl/gsl_errno.h>
#include <gsl/gsl_fft_real.h>
#include <gsl/gsl_fft_halfcomplex.h>

/* Changes:

     Added last_plot to fft plot; twf; Jan 05, 2016 

     Added the xb and xe axis to fft plot; twf; Jan 05, 2016 

 */

unsigned int powerOfTwo;

gsl_fft_real_wavetable        *fft_real = NULL;
gsl_fft_real_workspace        *fft_work = NULL;
gsl_fft_halfcomplex_wavetable *fft_hc   = NULL;
double                         fft_data[MAX_CHANS];

struct FFT_INFO last_fft;

int lp_fftcomp()
{
  int i, n, ret;
  double fr, f, bw;
  struct LP_IMAGE_INFO *image = h0;

  n = (int)image->head.noint;

  if(n == 0)
  {
    st_fail("No data loaded");

    return(0);
  }

  bzero((char *)&fft_data[0], sizeof(fft_data));

  st_report("FFT: N = %d", n);

  /* Copy floats to double array */
  for(i=0;i<n;i++)
  {
    fft_data[i] = image->yplot1[i];
  }
 
  /* Free up work and real structs if already allocated */
  if(fft_work)
  {
    gsl_fft_real_workspace_free (fft_work);
 
    fft_work = NULL;
  }

  if(fft_real)
  {
    gsl_fft_real_wavetable_free (fft_real);
 
    fft_real = NULL;
  }

  fft_work = gsl_fft_real_workspace_alloc (n);
  fft_real = gsl_fft_real_wavetable_alloc (n);

  ret = gsl_fft_real_transform (fft_data, 1, n, fft_real, fft_work);

  st_report("FFT: Function returned %d", ret);

  if(!ret)
  {
    fr = fabs(image->head.freqres);

        /* Double the n because that's the original BW */
        /* in this version of fft the results are 4 times??? */
    bw = (fr * (double)n * 2.0);
    f = 1.0 / bw;

    st_report("Freqres = %f MHz / Chan, BW = %f MHz", fr, fr * (double)n);

    strcpy(last_fft.magic, "FFT_INFO");

    bcopy((char *)&image->head, (char *)&last_fft.head, sizeof(last_fft.head));

    /* Skip the 0th lag */
    for(i=0;i<n/2;i++)
    {
      last_fft.xdata[i] = (double)i * f;
      last_fft.ydata[i] = fft_data[i] / bw * 2.0;
    }

    last_fft.num = n/2;

    if(env->fft_xb || env->fft_xe)
    {
      st_report("FFT Display Truncated");
      last_fft.xset = 1;
      last_fft.xb   = env->fft_xb;
      last_fft.xe   = env->fft_xe;
    }
    else
    {
      last_fft.xset = 0;
      last_fft.xb   = 0.0;
      last_fft.xe   = 0.0;
    }

    if(xgraphic)
    {
      sock_write(xgraphic, (char *)&last_fft, sizeof(last_fft));

      last_plot = LAST_PLOT_SPEC_FFT;

      st_report("Sent FFT to xgraphic");
    }
  }
  else
  {
    st_fail("FFT Failed");
  }

  return(0);
}


int findExactFFTFreq(mx)
double mx;
{
  int i, n, mindx=0;
  double min = 999999999.9;

  n = last_fft.num;

  st_report("FFT Num of Values           %d", n);
  for(i=0;i<n;i++)
  {
    if(fabs(last_fft.xdata[i] - mx) < min)
    {
      min = fabs(last_fft.xdata[i] - mx);
      mindx = i;

    }
  }

  st_report("FFT Found Index             %d", mindx);

  return(mindx);
}


int lp_fftpick()
{
  int i, n, nc, fft_indx;
  float *f1;
  double f, freeD, wireD, fft_freq;

  do
  {
    nc = getNumericResponse("Enter Number of Freqs [ Up to 8]: ");
  }
  while(nc < 0);

  if(nc > 8)
  {
    st_fail("Count out of range: 0x%x", nc);

    return(1);
  }

  for(i=0;i<nc;i++)
  {
    _doTCur("Click the Left Mouse Button on Desired Freq");

    fft_indx = findExactFFTFreq(last_mouse_x);
    fft_freq = last_fft.xdata[fft_indx];

    f = 1.0 / fft_freq;

    f *= 1e6;  /* Convert to Hz */

    freeD = 1.0 / f * SPEED_OF_LIGHT;
    wireD = 1.0 / f * SPEED_OF_LIGHT_COAX;

    freeD /= 2.0;
    wireD /= 2.0;

    st_report("MHz-1 Selected:        %7.4f uS", fft_freq);
    st_report("Freq Selected:         %7.4f MHz", f /= 1e6);
    st_report("Free Space Distance:   %7.4f Meters", freeD);
    st_report("Coaxial Wire Distance: %7.4f Meters", wireD);

    /* Zero out the bad freq */
    fft_data[fft_indx] = 0.0;
  }

  if(nc)
  {
    n = last_fft.num * 2;

    if(fft_work->n != n)
    {
      st_fail("FFT Elements don't match: %d vs %d", n, fft_work->n);
      return(0);
    }

    /* Convert back to Freq domain */
    fft_hc = gsl_fft_halfcomplex_wavetable_alloc(n);

    gsl_fft_halfcomplex_inverse(fft_data, 1, n, fft_hc, fft_work);

    gsl_fft_halfcomplex_wavetable_free(fft_hc);

    f1 = &h0->yplot1[0];
    for(i=0;i<n;i++,f1++)
    {
      *f1 = (float)fft_data[i];
    }

    xx();
  }

  return(0);
}


int lp_fftcut()
{
  int start, end;
  int i, n;
  float *f1;

  _doTCur("Click the Left Mouse Button on Left Freq");

  start = findExactFFTFreq(last_mouse_x);

  _doTCur("Click the Left Mouse Button on Right Freq");

  end = findExactFFTFreq(last_mouse_x);

  if(end > start)
  {
    for(i=start;i<end;i++)
    {
      fft_data[i] = 0.0;
    }
  }
  else
  {
    st_fail("Ending freq < Starting");
    return(1);
  }

  n = last_fft.num * 2;

  if(fft_work->n != n)
  {
    st_fail("FFT Elements don't match: %d vs %d", n, fft_work->n);
    return(0);
  }

    /* Convert back to Freq domain */
  fft_hc = gsl_fft_halfcomplex_wavetable_alloc(n);

  gsl_fft_halfcomplex_inverse(fft_data, 1, n, fft_hc, fft_work);

  gsl_fft_halfcomplex_wavetable_free(fft_hc);

  f1 = &h0->yplot1[0];
  for(i=0;i<n;i++,f1++)
  {
    *f1 = (float)fft_data[i];
  }

  xx();

  return(0);
}


int lp_fft()
{
  if(isSet(PF_A_FLAG))
  {
    if(strlen(args->secondArg))
    {
      env->fft_xb = atof(args->secondArg);
    }
    else
    {
      st_fail("Missing arg for 'fft /a xx.x xx.x'");
      return(1);
    }

    if(strlen(args->thirdArg))
    {
      env->fft_xe = atof(args->thirdArg);
    }
    else
    {
      st_fail("Missing arg for 'fft /a xx.x xx.x'");
      return(1);
    }

    return(0);
  }

  if(isSet(PF_C_FLAG))
  {
    lp_fftcut();
    return(0);
  }

  if(isSet(PF_P_FLAG))
  {
    lp_fftpick();
    return(0);
  }

  if(isSet(PF_R_FLAG))
  {
    st_report("Reseting fft plot axis to defaults");

    env->fft_xb = 0.0;
    env->fft_xe = 0.0;

    return(0);
  }

        /* else do an actual fft */
  lp_fftcomp();

  return(0);
}