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/* -*- C++ -*- */
/*
* Copyright 2008-2011 Steve Glass
*
* This file is part of OP25.
*
* OP25 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.
*
* OP25 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 OP25; see the file COPYING. If not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Boston, MA
* 02110-1301, USA.
*/
#ifndef INCLUDED_OP25_DECODER_FF_H
#define INCLUDED_OP25_DECODER_FF_H
#include <boost/scoped_ptr.hpp>
#include <data_unit.h>
#include <data_unit_handler.h>
#include <gr_block.h>
#include <gr_msg_queue.h>
#include <imbe_decoder.h>
typedef boost::shared_ptr<class op25_decoder_ff> op25_decoder_ff_sptr;
op25_decoder_ff_sptr op25_make_decoder_ff();
/**
* op25_decoder_ff is a GNU Radio block for decoding APCO P25
* signals. This class expects its input to be a stream of dibit
* symbols from the demodulator and produces a mono audio
* stream.
*/
class op25_decoder_ff : public gr_block
{
public:
/**
* op25_decoder_ff (virtual) destructor.
*/
virtual ~op25_decoder_ff();
/**
* Estimate nof_input_items_reqd for a given nof_output_items.
*/
virtual void forecast(int nof_output_items, gr_vector_int &nof_input_items_reqd);
/**
* Process symbols into frames.
*/
virtual int general_work(int nof_output_items, gr_vector_int& nof_input_items, gr_vector_const_void_star& input_items, gr_vector_void_star& output_items);
/**
* Return a pointer to a string identifying the destination of
* the received frames.
*
* \return A pointer to a NUL-terminated character string.
*/
const char *destination() const;
/**
* Accessor for the msgq attribute. Returns a pointer to the msgq
* if it exists.
*
* \return A (possibly NULL) gr_msg_queue_sptr pointing to the message queue.
*/
gr_msg_queue_sptr get_msgq() const;
/**
* Accessor for the msgq attribute. Sets the msgq to point to the
* provided message queue object.
*
* \return A (possibly NULL) gr_msg_queue_sptr pointing to the message queue.
*/
void set_msgq(gr_msg_queue_sptr msgq);
private:
/**
* Expose class to public ctor. Create a new instance of
* op25_decoder_ff and wrap it in a shared_ptr. This is effectively
* the public constructor.
*/
friend op25_decoder_ff_sptr op25_make_decoder_ff();
/**
* op25_decoder_ff protected constructor.
*/
op25_decoder_ff();
/**
* Tests whether d_frame_header correlates with the APCO P25 frame
* sync sequence. This method must only be called when the frame
* header is larger than 48 bits in length (the minimum size for
* the FS).
*
* \return true if the frame header correlates; otherwise false.
*/
bool correlated();
/**
* Tests whether d_frame_header identifies a known data unit and if
* so sets d_data_unit to point to an appropriate instance and
* returns a pointer to it. This method must only be called when
* the frame header is larger than 114 bits in length (the minimum
* size for a frame containing a NID).
*
* \return A data_unit_sptr pointing to an appropriate data_unit
* instance or NULL if the frame header is unrecognized.
*/
data_unit_sptr identified();
/**
* Handle a received symbol.
*
* \param d The symbol to process.
*/
void receive_symbol(dibit d);
private:
/**
* When d_state == READING the current data unit, otherwise null.
*/
data_unit_sptr d_data_unit;
/**
* The head of a chain of data_unit_handler instances.
*/
data_unit_handler_sptr d_data_unit_handler;
/**
* A bit_queue used to correlate the FS.
*/
bit_queue d_frame_hdr;
/**
* The IMBE decoder to use.
*/
imbe_decoder_sptr d_imbe;
/**
* Valid states for the decoder state model.
*/
enum { SYNCHRONIZING, IDENTIFYING, READING } d_state;
/**
* The p25cai (TUN/TAP) data unit handler.
*/
class p25cai_du_handler *d_p25cai_du_handler;
/**
* The snapshot data unit handler.
*/
class snapshot_du_handler *d_snapshot_du_handler;
};
#endif /* INCLUDED_OP25_DECODER_FF_H */
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