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/* -*- c++ -*- */
/*
* Copyright 2006,2010,2012 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "feedforward_agc_cc_impl.h"
#include <gnuradio/io_signature.h>
#include <stdexcept>
namespace gr {
namespace analog {
feedforward_agc_cc::sptr feedforward_agc_cc::make(int nsamples, float reference)
{
return gnuradio::make_block_sptr<feedforward_agc_cc_impl>(nsamples, reference);
}
feedforward_agc_cc_impl::feedforward_agc_cc_impl(int nsamples, float reference)
: sync_block("feedforward_agc_cc",
io_signature::make(1, 1, sizeof(gr_complex)),
io_signature::make(1, 1, sizeof(gr_complex))),
d_nsamples(nsamples),
d_reference(reference)
{
if (nsamples < 1)
throw std::invalid_argument("feedforward_agc_cc_impl: nsamples must be >= 1");
set_history(nsamples);
}
feedforward_agc_cc_impl::~feedforward_agc_cc_impl() {}
// approximate sqrt(x^2 + y^2)
inline static float envelope(gr_complex x)
{
float r_abs = std::fabs(x.real());
float i_abs = std::fabs(x.imag());
if (r_abs > i_abs)
return r_abs + 0.4 * i_abs;
else
return i_abs + 0.4 * r_abs;
}
int feedforward_agc_cc_impl::work(int noutput_items,
gr_vector_const_void_star& input_items,
gr_vector_void_star& output_items)
{
const gr_complex* in = (const gr_complex*)input_items[0];
gr_complex* out = (gr_complex*)output_items[0];
int nsamples = d_nsamples;
float gain;
for (int i = 0; i < noutput_items; i++) {
// float max_env = 1e-12; // avoid divide by zero
float max_env = 1e-4; // avoid divide by zero, indirectly set max gain
for (int j = 0; j < nsamples; j++) {
max_env = std::max(max_env, envelope(in[i + j]));
}
gain = d_reference / max_env;
out[i] = gain * in[i];
}
return noutput_items;
}
} /* namespace analog */
} /* namespace gr */
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