fft_filter_ccf.h

Go to the documentation of this file.

/* -*- c++ -*- */
/*
 * Copyright 2014 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 3, 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., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#ifndef INCLUDED_FILTER_FFT_FILTER_CCF_H
#define INCLUDED_FILTER_FFT_FILTER_CCF_H

#include <gnuradio/filter/api.h>
#include <gnuradio/sync_decimator.h>

namespace gr {
  namespace filter {

    /*!
     * \brief Fast FFT filter with gr_complex input, gr_complex output and float taps
     * \ingroup filter_blk
     *
     * \details
     * This block implements a complex decimating filter using the
     * fast convolution method via an FFT. The decimation factor is an
     * integer that is greater than or equal to 1.
     *
     * The filter takes a set of complex (or real) taps to use in the
     * filtering operation. These taps can be defined as anything that
     * satisfies the user's filtering needs. For standard filters such
     * as lowpass, highpass, bandpass, etc., the filter.firdes and
     * filter.optfir classes provide convenient generating methods.
     *
     * This filter is implemented by using the FFTW package to perform
     * the required FFTs. An optional argument, nthreads, may be
     * passed to the constructor (or set using the set_nthreads member
     * function) to split the FFT among N number of threads. This can
     * improve performance on very large FFTs (that is, if the number
     * of taps used is very large) if you have enough threads/cores to
     * support it.
     */
    class FILTER_API fft_filter_ccf : virtual public sync_decimator
    {
    public:
      // gr::filter::fft_filter_ccf::sptr
      typedef boost::shared_ptr<fft_filter_ccf> sptr;

      /*!
       * Build an FFT filter blocks.
       *
       * \param decimation  >= 1
       * \param taps        complex filter taps
       * \param nthreads    number of threads for the FFT to use
       */
      static sptr make(int decimation,
                       const std::vector<float> &taps,
                       int nthreads=1);

      virtual void set_taps(const std::vector<float> &taps) = 0;
      virtual std::vector<float> taps() const = 0;

      /*!
       * \brief Set number of threads to use.
       */
      virtual void set_nthreads(int n) = 0;

      /*!
       * \brief Get number of threads being used.
       */
      virtual int nthreads() const = 0;
    };

  } /* namespace filter */
} /* namespace gr */

#endif /* INCLUDED_FILTER_FFT_FILTER_CCF_H */