gr_fft_vfc.cc

gnuradio软件无线电源程序.现在的手机多基于软件无线电

/* -*- c++ -*- */
/*
 * Copyright 2004 Free Software Foundation, Inc.
 * 
 * This file is part of GNU Radio
 * 
 * GNU Radio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 * 
 * GNU Radio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <gr_fft_vfc.h>
#include <gr_io_signature.h>
#include <gri_fft.h>
#include <math.h>
#include <stdexcept>


// FIXME after this is working, change to use native real to complex fft.
// It should run twice as fast.


gr_fft_vfc_sptr
gr_make_fft_vfc (int fft_size, bool forward, bool window)
{
  return gr_fft_vfc_sptr (new gr_fft_vfc (fft_size, forward, window));
}

gr_fft_vfc::gr_fft_vfc (int fft_size, bool forward, bool window)
  : gr_sync_block ("fft_vfc",
		   gr_make_io_signature (1, 1, fft_size * sizeof (float)),
		   gr_make_io_signature (1, 1, fft_size * sizeof (gr_complex))),
    d_fft_size(fft_size), d_window(forward && window), d_winvals(0)
{
  if (!forward){
    fprintf (stderr, "fft_vfc: forward must == true\n");
    throw std::invalid_argument ("fft_vfc: forward must == true");
  }

  d_fft = new gri_fft_complex (d_fft_size, forward);

  if (d_window){
    d_winvals = new float[d_fft_size];
    for (int i = 0; i < d_fft_size; i++){
      d_winvals[i] = 0.54 - 0.46 * cos (2 * M_PI / d_fft_size * i); // Hamming window
      // d_winvals[i] = 0.5 - 0.5 * cos (2 * M_PI / d_fft_size * i);      // Hann window
    }
  }
}

gr_fft_vfc::~gr_fft_vfc ()
{
  delete d_fft;
  delete [] d_winvals;
}

int
gr_fft_vfc::work (int noutput_items,
		  gr_vector_const_void_star &input_items,
		  gr_vector_void_star &output_items)
{
  const float *in = (const float *) input_items[0];
  gr_complex *out = (gr_complex *) output_items[0];

  unsigned int output_data_size = output_signature()->sizeof_stream_item (0);

  int count = 0;

  while (count++ < noutput_items){

    // copy input into optimally aligned buffer

    if (d_window){
      gr_complex *dst = d_fft->get_inbuf();
      for (int i = 0; i < d_fft_size; i++)		// apply window
	dst[i] = in[i] * d_winvals[i];
    }
    else {
      gr_complex *dst = d_fft->get_inbuf();
      for (int i = 0; i < d_fft_size; i++)		// float to complex conversion
	dst[i] = in[i];				       
    }

    // compute the fft
    d_fft->execute ();

    // cpoy result to our output
    memcpy (out, d_fft->get_outbuf (), output_data_size);

    in  += d_fft_size;
    out += d_fft_size;
  }

  return noutput_items;
}