test_tag_variable_rate_ff.h

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/* -*- c++ -*- */
/*
 * Copyright 2015 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_GR_TEST_TAG_VARIABLE_RATE_FF_H
#define INCLUDED_GR_TEST_TAG_VARIABLE_RATE_FF_H
 
#include <gnuradio/block.h>
#include <gnuradio/blocks/api.h>
 
namespace gr {
namespace blocks {
 
/*!
 * \brief Used for testing tag propagation.
 * \ingroup measurement_tools_blk
 * \ingroup stream_tag_tools_blk
 * \ingroup debug_tools_blk
 *
 * This block resamples the stream by a factor that starts at 0.5
 * but varies around by some random walk. The relative rate of the
 * block is initialized to 0.5 and the random number generator is
 * seeded based on the time. For each input, if the random number
 * is >= 0.5, the relative rate is increased by \p update_step;
 * otherwise, it is decreased by \p update_step.
 *
 * The rate of the change of the resampling factor is set by the
 * flag \p update_once. If this is set to true, then the rate is
 * only updated once per work function. If it is set to false
 * (default), then the rate is changed with every input sample.
 *
 * The block's ctor sets the propagation policy to TPP_DONT to
 * stop tags from automatically propagating. Instead, we handle
 * the tag propagation ourselves from within the work
 * function. Because the relative_rate changes so fast, the tag
 * placement cannot be based on a single factor after the call to
 * work and must be handled when the samples are and based on the
 * current resampling rate.
 */
class BLOCKS_API test_tag_variable_rate_ff : virtual public block
{
public:
    // gr::blocks::test_tag_variable_rate_ff::sptr
    typedef boost::shared_ptr<test_tag_variable_rate_ff> sptr;
 
    /*!
     * Build a test_tag_variable_rate_ff block.
     *
     * \param update_once Update the resampling rate once per call
     *        to work (default=false).
     * \param update_step How much to adjust the resampling rate by
     *        when the update occurs (default=0.001).
     */
    static sptr make(bool update_once = false, double update_step = 0.001);
};
 
} /* namespace blocks */
} /* namespace gr */
 
#endif /* INCLUDED_GR_TEST_TAG_VARIABLE_RATE_FF_H */