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/* -*- c++ -*- */
/*
* Copyright 2020 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#ifndef INCLUDED_DIGITAL_ADAPTIVE_ALGORITHM_NLMS_H
#define INCLUDED_DIGITAL_ADAPTIVE_ALGORITHM_NLMS_H
#include <gnuradio/digital/adaptive_algorithm.h>
#include <volk/volk.h>
namespace gr {
namespace digital {
class DIGITAL_API adaptive_algorithm_nlms : public adaptive_algorithm
{
public:
typedef std::shared_ptr<adaptive_algorithm_nlms> sptr;
private:
const float d_step_size;
protected:
adaptive_algorithm_nlms(constellation_sptr cons, float step_size)
: adaptive_algorithm(adaptive_algorithm_t::NLMS, cons), d_step_size(step_size)
{
}
public:
static sptr make(constellation_sptr cons, float step_size)
{
return adaptive_algorithm_nlms::sptr(
new adaptive_algorithm_nlms(cons, step_size));
}
gr_complex update_tap(const gr_complex tap,
const gr_complex& in,
const gr_complex error,
const gr_complex decision) override
{
throw std::runtime_error(
"NLMS can only update all taps at once, single tap update is not valid");
}
void update_taps(gr_complex* taps,
const gr_complex* in,
const gr_complex error,
const gr_complex decision,
unsigned int num_taps) override
{
gr_complex dp;
volk_32fc_x2_conjugate_dot_prod_32fc(&dp, in, in, num_taps);
float magsq = real(dp);
float norm_step_size = d_step_size / magsq;
for (unsigned i = 0; i < num_taps; i++) {
taps[i] = conj(conj(taps[i]) + norm_step_size * in[i] * conj(error));
}
}
~adaptive_algorithm_nlms() override {}
void initialize_taps(std::vector<gr_complex>& taps) override
{
std::fill(taps.begin(), taps.end(), gr_complex(0.0, 0.0));
}
};
} // namespace digital
} // namespace gr
#endif
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