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/* -*- c++ -*- */
/*
* Copyright 2004,2010-2012,2014 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "clock_recovery_mm_ff_impl.h"
#include <gnuradio/io_signature.h>
#include <gnuradio/math.h>
#include <stdexcept>
namespace gr {
namespace digital {
clock_recovery_mm_ff::sptr
clock_recovery_mm_ff::make(float omega, float gain_omega,
float mu, float gain_mu,
float omega_relative_limit)
{
return gnuradio::get_initial_sptr
(new clock_recovery_mm_ff_impl(omega, gain_omega,
mu, gain_mu,
omega_relative_limit));
}
clock_recovery_mm_ff_impl::clock_recovery_mm_ff_impl(float omega, float gain_omega,
float mu, float gain_mu,
float omega_relative_limit)
: block("clock_recovery_mm_ff",
io_signature::make(1, 1, sizeof(float)),
io_signature::make(1, 1, sizeof(float))),
d_mu(mu), d_gain_mu(gain_mu), d_gain_omega(gain_omega),
d_omega_relative_limit(omega_relative_limit),
d_last_sample(0), d_interp(new filter::mmse_fir_interpolator_ff())
{
if(omega < 1)
throw std::out_of_range("clock rate must be > 0");
if(gain_mu < 0 || gain_omega < 0)
throw std::out_of_range("Gains must be non-negative");
set_omega(omega); // also sets min and max omega
set_relative_rate (1.0 / omega);
enable_update_rate(true); // fixes tag propagation through variable rate block
}
clock_recovery_mm_ff_impl::~clock_recovery_mm_ff_impl()
{
delete d_interp;
}
void
clock_recovery_mm_ff_impl::forecast(int noutput_items,
gr_vector_int &ninput_items_required)
{
unsigned ninputs = ninput_items_required.size();
for(unsigned i=0; i < ninputs; i++)
ninput_items_required[i] =
(int) ceil((noutput_items * d_omega) + d_interp->ntaps());
}
static inline float
slice(float x)
{
return x < 0 ? -1.0F : 1.0F;
}
void
clock_recovery_mm_ff_impl::set_omega (float omega)
{
d_omega = omega;
d_omega_mid = omega;
d_omega_lim = d_omega_mid * d_omega_relative_limit;
}
int
clock_recovery_mm_ff_impl::general_work(int noutput_items,
gr_vector_int &ninput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
const float *in = (const float *)input_items[0];
float *out = (float *)output_items[0];
int ii = 0; // input index
int oo = 0; // output index
int ni = ninput_items[0] - d_interp->ntaps(); // don't use more input than this
float mm_val;
while(oo < noutput_items && ii < ni ) {
// produce output sample
out[oo] = d_interp->interpolate(&in[ii], d_mu);
mm_val = slice(d_last_sample) * out[oo] - slice(out[oo]) * d_last_sample;
d_last_sample = out[oo];
d_omega = d_omega + d_gain_omega * mm_val;
d_omega = d_omega_mid + gr::branchless_clip(d_omega-d_omega_mid, d_omega_lim);
d_mu = d_mu + d_omega + d_gain_mu * mm_val;
ii += (int)floor(d_mu);
d_mu = d_mu - floor(d_mu);
oo++;
}
consume_each(ii);
return oo;
}
} /* namespace digital */
} /* namespace gr */
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