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/* -*- c++ -*- */
/* Copyright 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_DIGITAL_PACKET_HEADER_DEFAULT_H
#define INCLUDED_DIGITAL_PACKET_HEADER_DEFAULT_H
#include <gnuradio/tags.h>
#include <gnuradio/digital/api.h>
#include <boost/enable_shared_from_this.hpp>
#include <boost/crc.hpp>
namespace gr {
namespace digital {
/*!
* \brief Default header formatter for digital packet transmission.
* \ingroup packet_operators_blk
*
* \details
* For bursty/packetized digital transmission, packets are usually prepended
* with a packet header, containing the number of bytes etc.
* This class is not a block, but a tool to create these packet header.
*
* This is a default packet header (see header_formatter()) for a description
* on the header format). To create other header, derive packet header creator
* classes from this function.
*
* gr::digital::packet_headergenerator_bb uses header generators derived from
* this class to create packet headers from data streams.
*/
class DIGITAL_API packet_header_default
: public boost::enable_shared_from_this<gr::digital::packet_header_default>
{
public:
typedef boost::shared_ptr<packet_header_default> sptr;
packet_header_default(long header_len,
const std::string &len_tag_key="packet_len",
const std::string &num_tag_key="packet_num",
int bits_per_byte=1);
virtual ~packet_header_default();
sptr base() { return shared_from_this(); };
sptr formatter() { return shared_from_this(); };
void set_header_num(unsigned header_num) { d_header_number = header_num; };
long header_len() { return d_header_len; };
pmt::pmt_t len_tag_key() { return d_len_tag_key; };
/*!
* \brief Encodes the header information in the given tags into bits and places them into \p out
*
* Uses the following header format:
* Bits 0-11: The packet length (what was stored in the tag with key \p len_tag_key)
* Bits 12-23: The header number (counts up everytime this function is called)
* Bit 24-31: 8-Bit CRC
* All other bits: Are set to zero
*
* If the header length is smaller than 32, bits are simply left out. For this
* reason, they always start with the LSB.
*
* However, it is recommended to stay above 32 Bits, in order to have a working
* CRC.
*/
virtual bool header_formatter(long packet_len,
unsigned char *out,
const std::vector<tag_t> &tags=std::vector<tag_t>());
/*!
* \brief Inverse function to header_formatter().
*
* Reads the bit stream in \p header and writes a corresponding tag into \p tags.
*/
virtual bool header_parser(
const unsigned char *header,
std::vector<tag_t> &tags);
static sptr make(long header_len,
const std::string &len_tag_key="packet_len",
const std::string &num_tag_key="packet_num",
int bits_per_byte=1);
protected:
long d_header_len;
pmt::pmt_t d_len_tag_key;
pmt::pmt_t d_num_tag_key;
int d_bits_per_byte;
unsigned d_header_number;
unsigned d_mask;
boost::crc_optimal<8, 0x07, 0xFF, 0x00, false, false> d_crc_impl;
};
} // namespace digital
} // namespace gr
#endif /* INCLUDED_DIGITAL_PACKET_HEADER_DEFAULT_H */
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