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/* -*- c++ -*- */
/* Copyright 2015-2016 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_HEADER_FORMAT_COUNTER_H
#define INCLUDED_DIGITAL_HEADER_FORMAT_COUNTER_H
#include <pmt/pmt.h>
#include <gnuradio/digital/api.h>
#include <gnuradio/digital/header_format_default.h>
namespace gr {
namespace digital {
/*!
* \brief Header formatter that adds the payload bits/symbol
* format and a packet number counter.
* \ingroup packet_operators_blk
*
* \details
*
* Child class of header_format_default. This version adds two
* fields to the header:
*
* \li bps (16 bits): bits/symbol used when modulating the payload.
* \li count (16 bits): a counter for the packet number.
*
* Like the default packet formatter, the length is encoded as a
* 16-bit value repeated twice. The full packet looks like:
* \verbatim
| access code | hdr | payload |
\endverbatim
*
* Where the access code is <= 64 bits and hdr is:
* \verbatim
| 0 -- 15 | 16 -- 31 |
| pkt len | pkt len |
| bits/sym | counter |
\endverbatim
*
* The access code and header are formatted for network byte order.
*
* \sa header_format_default
*/
class DIGITAL_API header_format_counter
: public header_format_default
{
public:
header_format_counter(const std::string &access_code,
int threshold, int bps);
virtual ~header_format_counter();
/*!
* Creates a header from the access code and packet length to
* build an output packet in the form:
*
* \verbatim
| access code | pkt len | pkt len | bps | counter |
\endverbatim
*
* \param nbytes_in The length (in bytes) of the \p input payload
* \param input An array of unsigned chars of the packet payload
* \param output A pmt::u8vector with the new header prepended
* onto the input data.
* \param info A pmt::dict containing meta data and info about
* the PDU (generally from the metadata portion of the
* input PDU). Data can be extracted from this for the
* header formatting or inserted.
*/
virtual bool format(int nbytes_in,
const unsigned char *input,
pmt::pmt_t &output,
pmt::pmt_t &info);
/*!
* Returns the length of the formatted header in bits.
*/
virtual size_t header_nbits() const;
/*!
* Factory to create an async packet header formatter; returns
* an sptr to the object.
*
* \param access_code An access code that is used to find and
* synchronize the start of a packet. Used in the parser and in
* other blocks like a corr_est block that helps trigger the
* receiver. Can be up to 64-bits long.
* \param threshold How many bits can be wrong in the access
* code and still count as correct.
* \param bps The number of bits/second used in the payload's
* modulator.
*/
static sptr make(const std::string &access_code,
int threshold, int bps);
protected:
uint16_t d_counter; //!< keeps track of the number of packets transmitted
//! Verify that the header is valid
bool header_ok();
/*! Get info from the header; return payload length and package
* rest of data in d_info dictionary.
*
* Extracts the header of the form:
*
* \verbatim
| access code | pkt len | pkt len | bps | counter | payload |
\endverbatim
*/
int header_payload();
};
} // namespace digital
} // namespace gr
#endif /* INCLUDED_DIGITAL_HEADER_FORMAT_COUNTER_H */
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