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/* -*- c++ -*- */
/*
* Copyright 2005 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., 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 <errno.h>
#include <stdio.h>
#include <math.h>
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#ifdef HAVE_NANOSLEEP
void
gr_nanosleep(struct timespec *ts)
{
struct timespec *req = ts;
struct timespec rem;
int r = nanosleep(req, &rem);
while (r < 0 && errno == EINTR){
req = &rem;
r = nanosleep(req, &rem);
}
if (r < 0)
perror ("gr_nanosleep");
}
#endif
gr_throttle_sptr
gr_make_throttle(size_t itemsize, double samples_per_sec)
{
return gr_throttle_sptr(new gr_throttle(itemsize, samples_per_sec));
}
gr_throttle::gr_throttle(size_t itemsize, double samples_per_sec)
: gr_sync_block("throttle",
gr_make_io_signature(1, 1, itemsize),
gr_make_io_signature(1, 1, itemsize)),
d_itemsize(itemsize), d_samples_per_sec(samples_per_sec),
d_total_samples(0)
{
#ifdef HAVE_GETTIMEOFDAY
gettimeofday(&d_start, 0);
#endif
}
gr_throttle::~gr_throttle()
{
}
int
gr_throttle::work (int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
const char *in = (const char *) input_items[0];
char *out = (char *) output_items[0];
#if defined(HAVE_GETTIMEOFDAY) && defined(HAVE_NANOSLEEP)
//
// If our average sample rate exceeds our target sample rate,
// delay long enough to reduce to our target rate.
//
struct timeval now;
gettimeofday(&now, 0);
long t_usec = now.tv_usec - d_start.tv_usec;
long t_sec = now.tv_sec - d_start.tv_sec;
double t = (double)t_sec + (double)t_usec * 1e-6;
if (t < 1e-6) // avoid unlikely divide by zero
t = 1e-6;
double actual_samples_per_sec = d_total_samples / t;
if (actual_samples_per_sec > d_samples_per_sec){ // need to delay
double delay = d_total_samples / d_samples_per_sec - t;
struct timespec ts;
ts.tv_sec = (time_t)floor(delay);
ts.tv_nsec = (long)((delay - floor(delay)) * 1e9);
gr_nanosleep(&ts);
}
#endif
memcpy(out, in, noutput_items * d_itemsize);
d_total_samples += noutput_items;
return noutput_items;
}
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