txop.h

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2005 INRIA
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
 */

#ifndef TXOP_H
#define TXOP_H

#include "ns3/traced-value.h"
#include "wifi-mac-header.h"

namespace ns3 {

class Packet;
class ChannelAccessManager;
class MacTxMiddle;
class WifiMode;
class WifiMacQueue;
class WifiMacQueueItem;
class UniformRandomVariable;
class CtrlBAckResponseHeader;
class WifiRemoteStationManager;
enum WifiMacDropReason : uint8_t;  // opaque enum declaration
enum AcIndex : uint8_t;

class Txop : public Object
{
public:
  friend class MacLowTransmissionListener;

  Txop ();
  virtual ~Txop ();

  static TypeId GetTypeId (void);

  typedef Callback <void, WifiMacDropReason, Ptr<const WifiMacQueueItem> > DroppedMpdu;

  enum ChannelAccessStatus
  {
    NOT_REQUESTED = 0,
    REQUESTED,
    GRANTED
  };

  virtual bool IsQosTxop () const;
  virtual AcIndex GetAccessCategory (void) const;

  void SetChannelAccessManager (const Ptr<ChannelAccessManager> manager);
  virtual void SetWifiRemoteStationManager (const Ptr<WifiRemoteStationManager> remoteManager);
  void SetTxMiddle (const Ptr<MacTxMiddle> txMiddle);

  virtual void SetDroppedMpduCallback (DroppedMpdu callback);

  Ptr<WifiMacQueue > GetWifiMacQueue () const;

  void SetMinCw (uint32_t minCw);
  void SetMaxCw (uint32_t maxCw);
  void SetAifsn (uint8_t aifsn);
  void SetTxopLimit (Time txopLimit);
  uint32_t GetMinCw (void) const;
  uint32_t GetMaxCw (void) const;
  uint8_t GetAifsn (void) const;
  Time GetTxopLimit (void) const;
  void ResetCw (void);
  void UpdateFailedCw (void);

  virtual void NotifyChannelSwitching (void);
  virtual void NotifySleep (void);
  virtual void NotifyOff (void);
  virtual void NotifyWakeUp (void);
  virtual void NotifyOn (void);

  /* Event handlers */
  virtual void Queue (Ptr<Packet> packet, const WifiMacHeader &hdr);

  virtual void NotifyChannelAccessed (Time txopDuration = Seconds (0));
  virtual void NotifyChannelReleased (void);

  int64_t AssignStreams (int64_t stream);

  virtual ChannelAccessStatus GetAccessStatus (void) const;

  void StartBackoffNow (uint32_t nSlots);

protected:
  friend class ChannelAccessManager;

  void DoDispose (void) override;
  void DoInitialize (void) override;

  /* Txop notifications forwarded here */
  virtual void NotifyAccessRequested (void);
  virtual void NotifyInternalCollision (void);

  virtual bool HasFramesToTransmit (void);
  virtual void GenerateBackoff (void);
  virtual void StartAccessIfNeeded (void);
  void RequestAccess (void);

  uint32_t GetCw (void) const;
  uint32_t GetBackoffSlots (void) const;
  Time GetBackoffStart (void) const;
  void UpdateBackoffSlotsNow (uint32_t nSlots, Time backoffUpdateBound);

  Ptr<ChannelAccessManager> m_channelAccessManager; 
  DroppedMpdu m_droppedMpduCallback;                
  Ptr<WifiMacQueue> m_queue;                        
  Ptr<MacTxMiddle> m_txMiddle;                      
  Ptr<WifiRemoteStationManager> m_stationManager;   
  Ptr<UniformRandomVariable> m_rng;                 

  uint32_t m_cwMin;              
  uint32_t m_cwMax;              
  uint32_t m_cw;                 
  uint32_t m_backoff;            
  ChannelAccessStatus m_access;  
  uint32_t m_backoffSlots;       

  Time m_backoffStart;

  uint8_t m_aifsn;        
  Time m_txopLimit;       

  TracedCallback<uint32_t> m_backoffTrace;      
  TracedValue<uint32_t> m_cwTrace;              
};

} //namespace ns3

#endif /* TXOP_H */