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/* -*- c++ -*- */
/*
* Copyright 2005-2011 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gr_throttle.h>
#include <gr_io_signature.h>
#include <cstring>
#include <boost/thread/thread.hpp>
class gr_throttle_impl : public gr_throttle{
public:
gr_throttle_impl(size_t itemsize):
gr_sync_block("throttle",
gr_make_io_signature(1, 1, itemsize),
gr_make_io_signature(1, 1, itemsize)),
d_itemsize(itemsize)
{
/* NOP */
}
void set_sample_rate(double rate){
//changing the sample rate performs a reset of state params
d_start = boost::get_system_time();
d_total_samples = 0;
d_samps_per_tick = rate/boost::posix_time::time_duration::ticks_per_second();
d_samps_per_us = rate/1e6;
}
int work (
int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items
){
//calculate the expected number of samples to have passed through
boost::system_time now = boost::get_system_time();
boost::int64_t ticks = (now - d_start).ticks();
uint64_t expected_samps = uint64_t(d_samps_per_tick*ticks);
//if the expected samples was less, we need to throttle back
if (d_total_samples > expected_samps){
boost::this_thread::sleep(boost::posix_time::microseconds(
long((d_total_samples - expected_samps)/d_samps_per_us)
));
}
//copy all samples output[i] <= input[i]
const char *in = (const char *) input_items[0];
char *out = (char *) output_items[0];
std::memcpy(out, in, noutput_items * d_itemsize);
d_total_samples += noutput_items;
return noutput_items;
}
private:
boost::system_time d_start;
size_t d_itemsize;
uint64_t d_total_samples;
double d_samps_per_tick, d_samps_per_us;
};
gr_throttle::sptr
gr_make_throttle(size_t itemsize, double samples_per_sec)
{
gr_throttle::sptr throttle(new gr_throttle_impl(itemsize));
throttle->set_sample_rate(samples_per_sec);
return throttle;
}
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