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/* -*- c++ -*- */
/*
* Copyright 2009,2012 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 "hrpt_deframer_impl.h"
#include <gnuradio/io_signature.h>
#include <gnuradio/noaa/hrpt.h>
#include <cstring>
#include <cstdio>
namespace gr {
namespace noaa {
#define ST_IDLE 0
#define ST_SYNCED 1
hrpt_deframer::sptr
hrpt_deframer::make()
{
return gnuradio::get_initial_sptr
(new hrpt_deframer_impl());
}
hrpt_deframer_impl::hrpt_deframer_impl()
: block("noaa_hrpt_deframer",
io_signature::make(1, 1, sizeof(char)),
io_signature::make(1, 1, sizeof(short)))
{
set_output_multiple(6); // room for writing full sync when received
d_mid_bit = true;
d_last_bit = 0;
enter_idle();
}
hrpt_deframer_impl::~hrpt_deframer_impl()
{
}
void
hrpt_deframer_impl::enter_idle()
{
d_state = ST_IDLE;
}
void
hrpt_deframer_impl::enter_synced()
{
d_state = ST_SYNCED;
d_bit_count = HRPT_BITS_PER_WORD;
d_word_count = HRPT_MINOR_FRAME_WORDS-HRPT_SYNC_WORDS;
d_word = 0;
}
int
hrpt_deframer_impl::general_work(int noutput_items,
gr_vector_int &ninput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
int ninputs = ninput_items[0];
const char *in = (const char *)input_items[0];
unsigned short *out = (unsigned short *)output_items[0];
int i = 0, j = 0;
while(i < ninputs && j < noutput_items) {
char bit = in[i++];
char diff = bit^d_last_bit;
d_last_bit = bit;
// Wait for transition if not synced, otherwise, alternate bits
if(d_mid_bit && (diff | (d_state == ST_SYNCED))) {
switch(d_state) {
case ST_IDLE:
d_shifter = (d_shifter << 1) | bit; // MSB transmitted first
if((d_shifter & 0x0FFFFFFFFFFFFFFFLL) == HRPT_MINOR_FRAME_SYNC) {
out[j++] = HRPT_SYNC1;
out[j++] = HRPT_SYNC2;
out[j++] = HRPT_SYNC3;
out[j++] = HRPT_SYNC4;
out[j++] = HRPT_SYNC5;
out[j++] = HRPT_SYNC6;
enter_synced();
}
break;
case ST_SYNCED:
d_word = (d_word << 1) | bit; // MSB transmitted first
if(--d_bit_count == 0) {
out[j++] = d_word;
d_word = 0;
d_bit_count = HRPT_BITS_PER_WORD;
if(--d_word_count == 0) {
enter_idle();
}
}
break;
default:
throw std::runtime_error("hrpt_deframer_impl: bad state\n");
}
d_mid_bit = false;
}
else {
d_mid_bit = true;
}
}
consume_each(i);
return j;
}
} /* namespace noaa */
} /* namespace gr */
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