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Backoff.hpp

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/******************************************************************************
 * WiFiMac                                                                    *
 * This file is part of openWNS (open Wireless Network Simulator)
 * _____________________________________________________________________________
 *
 * Copyright (C) 2004-2007
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 * fax: ++49-241-80-22242
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 * _____________________________________________________________________________
 *
 * openWNS is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License version 2 as published by the
 * Free Software Foundation;
 *
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 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
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#ifndef WIFIMAC_LOWERMAC_TIMING_BACKOFF_HPP
#define WIFIMAC_LOWERMAC_TIMING_BACKOFF_HPP

#include <WIFIMAC/convergence/IChannelState.hpp>
#include <WIFIMAC/convergence/IRxStartEnd.hpp>

#include <WNS/Observer.hpp>

#include <WNS/events/MemberFunction.hpp>
#include <WNS/logger/Logger.hpp>
#include <WNS/distribution/Uniform.hpp>
#include <WNS/simulator/Time.hpp>
#include <WNS/events/CanTimeout.hpp>

namespace wifimac { namespace lowerMAC { namespace timing {

    class BackoffObserver
    {
    public:
        virtual
        ~BackoffObserver()
        {}

        virtual void backoffExpired() = 0;
    };

    class Backoff :
        public wns::events::CanTimeout,
        public wns::Observer<wifimac::convergence::IChannelState>,
        public wns::Observer<wifimac::convergence::IRxStartEnd>
    {
    public:

        Backoff(BackoffObserver* backoffObserver,
                const wns::pyconfig::View& config);

        ~Backoff();

        bool
        transmissionRequest(int transmissionCounter);

        // observer RxStartEnd
        void
        onRxStart(wns::simulator::Time expRxTime);
        void
        onRxEnd();
        void
        onRxError();

        void
        onChannelBusy();

        void
        onChannelIdle();

        int getCurrentCW() const
            {
                return(cw);
            }

        wns::simulator::Time
        finishedAt() const;

        void
        registerEOBObserver(BackoffObserver * observer);
    private:

        void startNewBackoffCountdown(wns::simulator::Time ifsDuration);

        void onTimeout();

        void waitForTimer(const wns::simulator::Time& waitDuration);

        void channelBusyDelay();

        BackoffObserver* backoffObserver;
        std::vector<BackoffObserver*> eobObserver;

        const wns::simulator::Time slotDuration;
        const wns::simulator::Time aifsDuration;
        const wns::simulator::Time eifsDuration;

        bool backoffFinished;
        bool transmissionWaiting;
        bool duringAIFS;
        bool rxError;

        const int cwMin;
        const int cwMax;
        int cw;
        wns::distribution::Uniform uniform;
        wns::logger::Logger logger;
        wns::simulator::Time aifsStart;
        bool channelIsBusy;

    protected:
        // For testing purpose this methods and variable is protected and may be
        // set by a special version of the backoff
        int counter;
    };
} // timing
} // lowerMAC
} // wifimac

#endif //  WIFIMAC_SCHEDULER_BACKOFF_HPP

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