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/* -*- c++ -*- */
/*
* Copyright 2004,2010,2012 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 <digital_packet_sink.h>
#include <gr_io_signature.h>
#include <cstdio>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdexcept>
#include <gr_count_bits.h>
#include <string.h>
#define VERBOSE 0
static const int DEFAULT_THRESHOLD = 12; // detect access code with up to DEFAULT_THRESHOLD bits wrong
inline void
digital_packet_sink::enter_search()
{
if (VERBOSE)
fprintf(stderr, "@ enter_search\n");
d_state = STATE_SYNC_SEARCH;
d_shift_reg = 0;
}
inline void
digital_packet_sink::enter_have_sync()
{
if (VERBOSE)
fprintf(stderr, "@ enter_have_sync\n");
d_state = STATE_HAVE_SYNC;
d_header = 0;
d_headerbitlen_cnt = 0;
}
inline void
digital_packet_sink::enter_have_header(int payload_len)
{
if (VERBOSE)
fprintf(stderr, "@ enter_have_header (payload_len = %d)\n", payload_len);
d_state = STATE_HAVE_HEADER;
d_packetlen = payload_len;
d_packetlen_cnt = 0;
d_packet_byte = 0;
d_packet_byte_index = 0;
}
digital_packet_sink_sptr
digital_make_packet_sink (const std::vector<unsigned char>& sync_vector,
gr_msg_queue_sptr target_queue, int threshold)
{
return gnuradio::get_initial_sptr(new digital_packet_sink (sync_vector, target_queue, threshold));
}
digital_packet_sink::digital_packet_sink (const std::vector<unsigned char>& sync_vector,
gr_msg_queue_sptr target_queue, int threshold)
: gr_sync_block ("packet_sink",
gr_make_io_signature (1, 1, sizeof(float)),
gr_make_io_signature (0, 0, 0)),
d_target_queue(target_queue), d_threshold(threshold == -1 ? DEFAULT_THRESHOLD : threshold)
{
d_sync_vector = 0;
for(int i=0;i<8;i++){
d_sync_vector <<= 8;
d_sync_vector |= sync_vector[i];
}
enter_search();
}
digital_packet_sink::~digital_packet_sink ()
{
}
int
digital_packet_sink::work (int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
float *inbuf = (float *) input_items[0];
int count=0;
if (VERBOSE)
fprintf(stderr,">>> Entering state machine\n"),fflush(stderr);
while (count<noutput_items) {
switch(d_state) {
case STATE_SYNC_SEARCH: // Look for sync vector
if (VERBOSE)
fprintf(stderr,"SYNC Search, noutput=%d\n",noutput_items),fflush(stderr);
while (count < noutput_items) {
if(slice(inbuf[count++]))
d_shift_reg = (d_shift_reg << 1) | 1;
else
d_shift_reg = d_shift_reg << 1;
// Compute popcnt of putative sync vector
if(gr_count_bits64 (d_shift_reg ^ d_sync_vector) <= d_threshold) {
// Found it, set up for header decode
enter_have_sync();
break;
}
}
break;
case STATE_HAVE_SYNC:
if (VERBOSE)
fprintf(stderr,"Header Search bitcnt=%d, header=0x%08x\n", d_headerbitlen_cnt, d_header),
fflush(stderr);
while (count < noutput_items) { // Shift bits one at a time into header
if(slice(inbuf[count++]))
d_header = (d_header << 1) | 1;
else
d_header = d_header << 1;
if (++d_headerbitlen_cnt == HEADERBITLEN) {
if (VERBOSE)
fprintf(stderr, "got header: 0x%08x\n", d_header);
// we have a full header, check to see if it has been received properly
if (header_ok()){
int payload_len = header_payload_len();
if (payload_len <= MAX_PKT_LEN) // reasonable?
enter_have_header(payload_len); // yes.
else
enter_search(); // no.
}
else
enter_search(); // no.
break; // we're in a new state
}
}
break;
case STATE_HAVE_HEADER:
if (VERBOSE)
fprintf(stderr,"Packet Build\n"),fflush(stderr);
while (count < noutput_items) { // shift bits into bytes of packet one at a time
if(slice(inbuf[count++]))
d_packet_byte = (d_packet_byte << 1) | 1;
else
d_packet_byte = d_packet_byte << 1;
if (d_packet_byte_index++ == 7) { // byte is full so move to next byte
d_packet[d_packetlen_cnt++] = d_packet_byte;
d_packet_byte_index = 0;
if (d_packetlen_cnt == d_packetlen){ // packet is filled
// build a message
gr_message_sptr msg = gr_make_message(0, 0, 0, d_packetlen_cnt);
memcpy(msg->msg(), d_packet, d_packetlen_cnt);
d_target_queue->insert_tail(msg); // send it
msg.reset(); // free it up
enter_search();
break;
}
}
}
break;
default:
assert(0);
} // switch
} // while
return noutput_items;
}
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