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/* -*- c++ -*- */
/*
* Copyright 2005,2006,2012 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.
*/
#ifndef INCLUDED_GR_FRAMER_SINK_1_H
#define INCLUDED_GR_FRAMER_SINK_1_H
#include <digital_api.h>
#include <gr_sync_block.h>
#include <gr_msg_queue.h>
class digital_framer_sink_1;
typedef boost::shared_ptr<digital_framer_sink_1> digital_framer_sink_1_sptr;
DIGITAL_API digital_framer_sink_1_sptr
digital_make_framer_sink_1(gr_msg_queue_sptr target_queue);
/*!
* \brief Given a stream of bits and access_code flags, assemble packets.
* \ingroup sink_blk
*
* input: stream of bytes from gr_correlate_access_code_bb
* output: none. Pushes assembled packet into target queue
*
* The framer expects a fixed length header of 2 16-bit shorts
* containing the payload length, followed by the payload. If the
* 2 16-bit shorts are not identical, this packet is ignored. Better
* algs are welcome.
*
* The input data consists of bytes that have two bits used.
* Bit 0, the LSB, contains the data bit.
* Bit 1 if set, indicates that the corresponding bit is the
* the first bit of the packet. That is, this bit is the first
* one after the access code.
*/
class DIGITAL_API digital_framer_sink_1 : public gr_sync_block
{
friend DIGITAL_API digital_framer_sink_1_sptr
digital_make_framer_sink_1(gr_msg_queue_sptr target_queue);
private:
enum state_t {STATE_SYNC_SEARCH, STATE_HAVE_SYNC, STATE_HAVE_HEADER};
static const int MAX_PKT_LEN = 4096;
static const int HEADERBITLEN = 32;
gr_msg_queue_sptr d_target_queue; // where to send the packet when received
state_t d_state;
unsigned int d_header; // header bits
int d_headerbitlen_cnt; // how many so far
unsigned char d_packet[MAX_PKT_LEN]; // assembled payload
unsigned char d_packet_byte; // byte being assembled
int d_packet_byte_index; // which bit of d_packet_byte we're working on
int d_packetlen; // length of packet
int d_packet_whitener_offset; // offset into whitener string to use
int d_packetlen_cnt; // how many so far
protected:
digital_framer_sink_1(gr_msg_queue_sptr target_queue);
void enter_search();
void enter_have_sync();
void enter_have_header(int payload_len, int whitener_offset);
bool header_ok()
{
// confirm that two copies of header info are identical
return ((d_header >> 16) ^ (d_header & 0xffff)) == 0;
}
void header_payload(int *len, int *offset)
{
// header consists of two 16-bit shorts in network byte order
// payload length is lower 12 bits
// whitener offset is upper 4 bits
*len = (d_header >> 16) & 0x0fff;
*offset = (d_header >> 28) & 0x000f;
}
public:
~digital_framer_sink_1();
int work(int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items);
};
#endif /* INCLUDED_GR_FRAMER_SINK_1_H */
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