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/* -*- c++ -*- */
/*
* Copyright 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 "ccsds_encoder_impl.h"
#include <gnuradio/fec/generic_encoder.h>
#include <cstdio>
extern "C" {
#include <gnuradio/fec/viterbi.h>
}
namespace gr {
namespace fec {
namespace code {
generic_encoder::sptr
ccsds_encoder::make(int frame_size, int start_state,
cc_mode_t mode)
{
return generic_encoder::sptr
(new ccsds_encoder_impl(frame_size, start_state, mode));
}
ccsds_encoder_impl::ccsds_encoder_impl(int frame_size, int start_state,
cc_mode_t mode)
: generic_encoder("ccsds_encoder"),
d_start_state(static_cast<unsigned char>(start_state)),
d_mode(mode)
{
d_max_frame_size = frame_size;
set_frame_size(frame_size);
}
ccsds_encoder_impl::~ccsds_encoder_impl()
{
}
int
ccsds_encoder_impl::get_output_size()
{
return d_output_size;
}
int
ccsds_encoder_impl::get_input_size()
{
return d_frame_size/8; // packed byte input
}
const char*
ccsds_encoder_impl::get_input_conversion()
{
// Expects packed data input; tell wrapper to pack it.
return "pack";
}
bool
ccsds_encoder_impl::set_frame_size(unsigned int frame_size)
{
bool ret = true;
if(frame_size > d_max_frame_size) {
GR_LOG_INFO(d_logger, boost::format("tried to set frame to %1%; max possible is %2%") \
% frame_size % d_max_frame_size);
frame_size = d_max_frame_size;
ret = false;
}
d_frame_size = frame_size;
if(d_mode == CC_TERMINATED) {
d_output_size = 2*(d_frame_size + 7 - 1);
}
else {
d_output_size = 2*d_frame_size;
}
return ret;
}
double
ccsds_encoder_impl::rate()
{
return 0.5;
}
void
ccsds_encoder_impl::generic_work(void *in_buffer, void *out_buffer)
{
unsigned char *in = (unsigned char*) in_buffer;
unsigned char *out = (unsigned char*) out_buffer;
unsigned char my_state = d_start_state;
if(d_mode == CC_TAILBITING) {
// Grab K-1 (6) bits of data from the last input byte to add
// onto the from of the encoding stream for tailbiting mode.
unsigned char sym = in[d_frame_size/8 - 1];
for(unsigned int i = 0; i < 7 - 1; ++i) {
my_state = (my_state << 1) | ((sym >> (5 - i)) & 1);
}
}
my_state = encode(out, in, d_frame_size/8, my_state);
if(d_mode == CC_TERMINATED) {
// encode works on bytes, but we are only adding some number
// of bits to the end of the frame, so we abuse the encode
// function by reshifting the start state within the
// for-loop and only taking the last two bits out of the
// encoded 2-bytes.
unsigned char end_bits[16];
for(unsigned int i = 0; i < (7 - 1); ++i) {
my_state = (my_state << 1) | ((d_start_state >> (7 - 2 - i)) & 1);
encode(&end_bits[0], &my_state, 1, my_state);
out[(i + d_frame_size) * 2 + 0] = end_bits[14];
out[(i + d_frame_size) * 2 + 1] = end_bits[15];
}
}
if(d_mode == CC_TRUNCATED) {
my_state = d_start_state;
}
d_start_state = my_state;
}
} /* namespace code */
} /* namespace fec */
} /* namespace gr */
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