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/* -*- c++ -*- */
/*
* Copyright 2009 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 <noaa_hrpt_deframer.h>
#include <gr_io_signature.h>
#include <noaa_hrpt.h>
#include <cstring>
#include <cstdio>
#define ST_IDLE 0
#define ST_SYNCED 1
noaa_hrpt_deframer_sptr
noaa_make_hrpt_deframer()
{
return gnuradio::get_initial_sptr(new noaa_hrpt_deframer());
}
noaa_hrpt_deframer::noaa_hrpt_deframer()
: gr_block("noaa_hrpt_deframer",
gr_make_io_signature(1, 1, sizeof(char)),
gr_make_io_signature(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();
}
void
noaa_hrpt_deframer::enter_idle()
{
d_state = ST_IDLE;
}
void
noaa_hrpt_deframer::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
noaa_hrpt_deframer::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("noaa_hrpt_deframer: bad state\n");
}
d_mid_bit = false;
}
else {
d_mid_bit = true;
}
}
consume_each(i);
return j;
}
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