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/* -*- c++ -*- */
/*
* Copyright 2006,2010,2012 Free Software Foundation, Inc.
* Copyright 2021 Daniel Estevez <daniel@destevez.net>
*
* This file is part of GNU Radio
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "diff_encoder_bb_impl.h"
#include <gnuradio/io_signature.h>
#include <stdexcept>
namespace gr {
namespace digital {
diff_encoder_bb::sptr diff_encoder_bb::make(unsigned int modulus,
enum diff_coding_type coding)
{
return gnuradio::make_block_sptr<diff_encoder_bb_impl>(modulus, coding);
}
diff_encoder_bb_impl::diff_encoder_bb_impl(unsigned int modulus,
enum diff_coding_type coding)
: sync_block("diff_encoder_bb",
io_signature::make(1, 1, sizeof(unsigned char)),
io_signature::make(1, 1, sizeof(unsigned char))),
d_last_out(0),
d_modulus(modulus),
d_coding(coding)
{
if (d_coding == DIFF_NRZI && d_modulus != 2) {
throw std::runtime_error("diff_encoder: NRZI only supported with modulus 2");
}
}
diff_encoder_bb_impl::~diff_encoder_bb_impl() {}
int diff_encoder_bb_impl::work(int noutput_items,
gr_vector_const_void_star& input_items,
gr_vector_void_star& output_items)
{
const unsigned char* in = (const unsigned char*)input_items[0];
unsigned char* out = (unsigned char*)output_items[0];
unsigned last_out = d_last_out;
if (d_coding == DIFF_NRZI) {
for (int i = 0; i < noutput_items; i++) {
out[i] = ~(in[i] ^ last_out) & 1;
last_out = out[i];
}
} else if (d_modulus == 2) {
// optimized implementation for modulus 2
for (int i = 0; i < noutput_items; i++) {
out[i] = (in[i] ^ last_out) & 1;
last_out = out[i];
}
} else {
// implementation for modulus != 2
for (int i = 0; i < noutput_items; i++) {
out[i] = (in[i] + last_out) % d_modulus;
last_out = out[i];
}
}
d_last_out = last_out;
return noutput_items;
}
} /* namespace digital */
} /* namespace gr */
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