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/* -*- c++ -*- */
/*
* Copyright 2014 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 "atsc_types.h"
#include "atsc_viterbi_decoder_impl.h"
#include "atsc_viterbi_mux.h"
#include <gnuradio/io_signature.h>
namespace gr {
namespace dtv {
atsc_viterbi_decoder::sptr atsc_viterbi_decoder::make()
{
return gnuradio::make_block_sptr<atsc_viterbi_decoder_impl>();
}
atsc_viterbi_decoder_impl::atsc_viterbi_decoder_impl()
: sync_block(
"dtv_atsc_viterbi_decoder",
io_signature::make2(
2, 2, sizeof(float) * ATSC_DATA_SEGMENT_LENGTH, sizeof(plinfo)),
io_signature::make2(
2, 2, sizeof(unsigned char) * ATSC_MPEG_RS_ENCODED_LENGTH, sizeof(plinfo)))
{
set_output_multiple(NCODERS);
/*
* These fifo's handle the alignment problem caused by the
* inherent decoding delay of the individual viterbi decoders.
* The net result is that this entire block has a pipeline latency
* of 12 complete segments.
*
* If anybody cares, it is possible to do it with less delay, but
* this approach is at least somewhat understandable...
*/
// the -4 is for the 4 sync symbols
const int fifo_size = ATSC_DATA_SEGMENT_LENGTH - 4 - viterbi[0].delay();
fifo.reserve(NCODERS);
for (int i = 0; i < NCODERS; i++)
fifo.emplace_back(fifo_size);
reset();
}
atsc_viterbi_decoder_impl::~atsc_viterbi_decoder_impl() {}
void atsc_viterbi_decoder_impl::reset()
{
for (int i = 0; i < NCODERS; i++)
fifo[i].reset();
}
std::vector<float> atsc_viterbi_decoder_impl::decoder_metrics() const
{
std::vector<float> metrics(NCODERS);
for (int i = 0; i < NCODERS; i++)
metrics[i] = viterbi[i].best_state_metric();
return metrics;
}
int atsc_viterbi_decoder_impl::work(int noutput_items,
gr_vector_const_void_star& input_items,
gr_vector_void_star& output_items)
{
auto in = static_cast<const float*>(input_items[0]);
auto out = static_cast<unsigned char*>(output_items[0]);
auto plin = static_cast<const plinfo*>(input_items[1]);
auto plout = static_cast<plinfo*>(output_items[1]);
// The way the fs_checker works ensures we start getting packets
// starting with a field sync, and out input multiple is set to
// 12, so we should always get a mod 12 numbered first packet
assert(noutput_items % NCODERS == 0);
int dbwhere;
int dbindex;
int shift;
float symbols[NCODERS][enco_which_max];
unsigned char dibits[NCODERS][enco_which_max];
unsigned char out_copy[OUTPUT_SIZE];
std::vector<tag_t> tags;
for (int i = 0; i < noutput_items; i += NCODERS) {
/* Build a continuous symbol buffer for each encoder */
for (unsigned int encoder = 0; encoder < NCODERS; encoder++)
for (unsigned int k = 0; k < enco_which_max; k++)
symbols[encoder][k] =
in[(i + (enco_which_syms[encoder][k] / ATSC_DATA_SEGMENT_LENGTH)) *
ATSC_DATA_SEGMENT_LENGTH +
enco_which_syms[encoder][k] % ATSC_DATA_SEGMENT_LENGTH];
/* Now run each of the 12 Viterbi decoders over their subset of
the input symbols */
for (unsigned int encoder = 0; encoder < NCODERS; encoder++)
for (unsigned int k = 0; k < enco_which_max; k++)
dibits[encoder][k] = viterbi[encoder].decode(symbols[encoder][k]);
/* Move dibits into their location in the output buffer */
for (unsigned int encoder = 0; encoder < NCODERS; encoder++) {
for (unsigned int k = 0; k < enco_which_max; k++) {
/* Store the dibit into the output data segment */
dbwhere = enco_which_dibits[encoder][k];
dbindex = dbwhere >> 3;
shift = dbwhere & 0x7;
out_copy[dbindex] = (out_copy[dbindex] & ~(0x03 << shift)) |
(fifo[encoder].stuff(dibits[encoder][k]) << shift);
} /* Symbols fed into one encoder */
} /* Encoders */
// copy output from contiguous temp buffer into final output
for (int j = 0; j < NCODERS; j++) {
memcpy(&out[(i + j) * ATSC_MPEG_RS_ENCODED_LENGTH],
&out_copy[j * ATSC_MPEG_RS_ENCODED_LENGTH],
ATSC_MPEG_RS_ENCODED_LENGTH * sizeof(out_copy[0]));
plout[i + j] = plinfo();
// adjust pipeline info to reflect 12 segment delay
plinfo::delay(plout[i + j], plin[i + j], NCODERS);
}
}
return noutput_items;
}
void atsc_viterbi_decoder_impl::setup_rpc()
{
#ifdef GR_CTRLPORT
add_rpc_variable(
rpcbasic_sptr(new rpcbasic_register_get<atsc_viterbi_decoder, std::vector<float>>(
alias(),
"decoder_metrics",
&atsc_viterbi_decoder::decoder_metrics,
pmt::make_f32vector(1, 0),
pmt::make_f32vector(1, 100000),
pmt::make_f32vector(1, 0),
"",
"Viterbi decoder metrics",
RPC_PRIVLVL_MIN,
DISPTIME)));
#endif /* GR_CTRLPORT */
}
} /* namespace dtv */
} /* namespace gr */
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