/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2007 Emmanuelle Laprise

 *

 * 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: Emmanuelle Laprise <emmanuelle.laprise@bluekazoo.ca

 * Derived from the p2p net device file

 */

#ifndef CSMA_CD_NET_DEVICE_H

#define CSMA_CD_NET_DEVICE_H

#include <string.h>

#include "ns3/node.h"

#include "ns3/backoff.h"

#include "ns3/mac-address.h"

#include "ns3/net-device.h"

#include "ns3/callback.h"

#include "ns3/packet.h"

#include "ns3/callback-trace-source.h"

#include "ns3/nstime.h"

#include "ns3/data-rate.h"

#include "ns3/ptr.h"

#include "ns3/random-variable.h"

namespace ns3 {

class Queue;

class CsmaCdChannel;

/**

 * \class CsmaCdNetDevice

 * \brief A Device for a CsmaCd Network Link.

 *

 * The Csma/Cd net device class is analogous to layer 1 and 2 of the

 * TCP stack. The NetDevice takes a raw packet of bytes and creates a

 * protocol specific packet from them. The Csma/Cd net device class

 * takes this packet and adds and processes the headers/trailers that

 * are associated with EthernetV1, EthernetV2, RAW or LLC

 * protocols. The EthernetV1 packet type adds and removes Ethernet

 * destination and source addresses. The LLC packet type adds and

 * removes LLC snap headers. The raw packet type does not add or

 * remove any headers.  Each Csma/Cd net device will receive all

 * packets written to the Csma/Cd link. The ProcessHeader function can

 * be used to filter out the packets such that higher level layers

 * only receive packets that are addressed to their associated net

 * devices

 *

 */

class CsmaCdNetDevice : public NetDevice {

public:

  /**

   * Enumeration of the types of traces supported in the class.

   *

   */

  enum TraceType {

    QUEUE, /**< Trace queue events on the attached queue */

    RX,    /**< Trace packet reception events (from the channel) */

    DROP    /**< Trace packet drop events (from the channel) */

  };

  /**

   * Enumeration of the types of packets supported in the class.

   *

   */

enum CsmaCdEncapsulationMode {

  ETHERNET_V1, /**< Version one ethernet packet, length field */

  IP_ARP,      /**< Ethernet packet encapsulates IP/ARP packet */

  RAW,         /**< Packet that contains no headers */

  LLC,         /**< LLC packet encapsulation */  

};

  /**

   * Construct a CsmaCdNetDevice

   *

   * This is the constructor for the CsmaCdNetDevice.  It takes as a

   * parameter the Node to which this device is connected.  Ownership of the

   * Node pointer is not implied and the node must not be deleted.

   *

   * \param node the Node to which this device is connected.

   * \param addr The source MAC address of the net device.

   */

  CsmaCdNetDevice (Ptr<Node> node, MacAddress addr, CsmaCdEncapsulationMode pktType);

  CsmaCdNetDevice (Ptr<Node> node, MacAddress addr,

                   CsmaCdEncapsulationMode pktType,

                   bool sendEnable, bool receiveEnable);

  /**

   * Copy Construct a CsmaCdNetDevice

   *

   * This is the copy constructor for the CsmaCdNetDevice.  This is

   * primarily used in topology creation.

   *

   * \param nd the object to be copied

   */

  CsmaCdNetDevice (const CsmaCdNetDevice& nd);

  /**

   * Destroy a CsmaCdNetDevice

   *

   * This is the destructor for the CsmaCdNetDevice.

   */

  virtual ~CsmaCdNetDevice();

  /**

   * Assignment Operator for a CsmaCdNetDevice

   *

   * This is the assignment operator for the CsmaCdNetDevice.  This is

   * to allow

   *

   * \param nd the object to be copied

   */

  // CsmaCdNetDevice& operator= (CsmaCdNetDevice nd);

  /**

   * Set the Data Rate used for transmission of packets.  The data rate is

   * set in the Attach () method from the corresponding field in the channel

   * to which the device is attached.  It can be overridden using this method.

   *

   * @see Attach ()

   * \param bps the data rate at which this object operates

   */

  void SetDataRate (DataRate bps);

  /**

   * Set the inteframe gap used to separate packets.  The interframe gap

   * defines the minimum space required between packets sent by this device.

   * It is usually set in the Attach () method based on the speed of light

   * delay of the channel to which the device is attached.  It can be 

   * overridden using this method if desired.

   *

   * @see Attach ()

   * \param t the interframe gap time

   */

  void SetInterframeGap (Time t);

  /**

   * Set the backoff parameters used to determine the wait to retry

   * transmitting a packet when the channel is busy.

   *

   * @see Attach ()

   * \param slotTime Length of a packet slot (or average packet time)

   * \param minSlots Minimum number of slots to wait

   * \param maxSlots Maximum number of slots to wait

   * \param maxRetries Maximum number of retries before packet is discard

   * \param ceiling Cap on the exponential function when calculating max slots

   */

  void SetBackoffParams (Time slotTime, uint32_t minSlots, uint32_t maxSlots, 

                        uint32_t maxRetries, uint32_t ceiling);

  /**

   * Attach the device to a channel.

   *

   * The function Attach is used to add a CsmaCdNetDevice to a

   * CsmaCdChannel.

   *

   * @see SetDataRate ()

   * @see SetInterframeGap ()

   * \param ch a pointer to the channel to which this object is being attached.

   */

  bool Attach (Ptr<CsmaCdChannel> ch);

  /**

   * Attach a queue to the CsmaCdNetDevice.

   *

   * The CsmaCdNetDevice "owns" a queue.  This queue is created by the

   * CsmaCdTopology object and implements a queueing method such as

   * DropTail or RED.  The CsmaCdNetDevice assumes ownership of this

   * queue and must delete it when the device is destroyed.

   *

   * @see CsmaCdTopology::AddCsmaCdLink ()

   * @see Queue

   * @see DropTailQueue

   * \param queue a pointer to the queue for which object is assuming

   *        ownership.

   */

  void AddQueue (Ptr<Queue> queue);

  /**

   * Receive a packet from a connected CsmaCdChannel.

   *

   * The CsmaCdNetDevice receives packets from its connected channel

   * and forwards them up the protocol stack.  This is the public method

   * used by the channel to indicate that the last bit of a packet has 

   * arrived at the device.

   *

   * @see CsmaCdChannel

   * \param p a reference to the received packet

   */

  void Receive (Packet& p);

  bool IsSendEnabled (void);

  bool IsReceiveEnabled (void);

  void SetSendEnable (bool);

  void SetReceiveEnable (bool);

protected:

  virtual bool DoNeedsArp (void) const;

  virtual void DoDispose (void);

  /**

   * Get a copy of the attached Queue.

   *

   * This method is provided for any derived class that may need to get

   * direct access to the underlying queue.

   *

   * \return a pointer to the queue.

   */

  Ptr<Queue> GetQueue (void) const; 

  /**

   * Get a copy of the attached Channel

   *

   * This method is provided for any derived class that may need to get

   * direct access to the connected channel

   *

   * \return a pointer to the channel

   */

  virtual Ptr<Channel> DoGetChannel (void) const;

  /**

   * Adds the necessary headers and trailers to a packet of data in order to

   * respect the packet type

   *

   * \param p Packet to which header should be added

   * \param dest MAC destination address to which packet should be sent

   * \param protocolNumber In some protocols, identifies the type of

   * payload contained in this packet.

   */

  void AddHeader (Packet& p, const MacAddress& dest, 

                  uint16_t protocolNumber);

  /**

   * Removes, from a packet of data, all headers and trailers that

   * relate to the packet type

   *

   * \param p Packet whose headers need to be processed

   * \param param An integer parameter that can be set by the function

   * to return information gathered in the header

   * \return Returns true if the packet should be forwarded up the

   * protocol stack.

   */

  bool ProcessHeader (Packet& p, int& param);

private:

  /**

   * Initializes variablea when construction object.

   */

  void Init (bool sendEnable, bool receiveEnable);

  /**

   * Send a Packet on the Csma/Cd network

   *

   * This method does not use a destination address since all packets

   * are broadcast to all NetDevices attached to the channel. Packet

   * should contain all needed headers at this time.

   *

   * If the device is ready to transmit, the next packet is read off

   * of the queue and stored locally until it has been transmitted.

   *

   * \param p a reference to the packet to send

   * \param dest destination address

   * \param protocolNumber -- this parameter is not used here

   * \return true if success, false on failure

   */

  virtual bool SendTo (Packet& p, const MacAddress& dest, uint16_t protocolNumber);

  /**

   * Start Sending a Packet Down the Wire.

   *

   * The TransmitStart method is the method that is used internally in

   * the CsmaCdNetDevice to begin the process of sending a packet

   * out on the channel.  The corresponding method is called on the

   * channel to let it know that the physical device this class

   * represents has virually started sending signals, this causes the

   * channel to become busy.  An event is scheduled for the time at

   * which the bits have been completely transmitted. If the channel

   * is busy, the method reschedules itself for a later time (within

   * the backoff period)

   *

   * @see CsmaCdChannel::TransmitStart ()

   * @see TransmitCompleteEvent ()

   */

  void TransmitStart ();

  /**

   * Stop Sending a Packet Down the Wire and Begin the Interframe Gap.

   *

   * The TransmitCompleteEvent method is used internally to finish the process

   * of sending a packet out on the channel.  During execution of this method

   * the TransmitEnd method is called on the channel to let it know that the

   * physical device this class represents has virually finished sending 

   * signals.  The channel uses this event to begin its speed of light delay

   * timer after which it notifies the Net Device at the other end of the 

   * link that the bits have arrived.  During this method, the net device 

   * also schedules the TransmitReadyEvent at which time the transmitter 

   * becomes ready to send the next packet.

   *

   * @see CsmaCdChannel::TransmitEnd ()

   * @see TransmitReadyEvent ()

   */

  void TransmitCompleteEvent (void);

  /**

   * Cause the Transmitter to Become Ready to Send Another Packet.

   *

   * The TransmitReadyEvent method is used internally to re-enable the 

   * transmit machine of the net device.  It is scheduled after a suitable

   * interframe gap after the completion of the previous transmission.

   * The queue is checked at this time, and if there is a packet waiting on

   * the queue, the transmission process is begun.

   *

   * If a packet is in the queue, it is extracted for the queue as the

   * next packet to be transmitted by the net device.

   *

   * @see TransmitStart ()

   */

  void TransmitReadyEvent (void);

  /**

   * Create a Trace Resolver for events in the net device.

   * (NOT TESTED)

   * @see class TraceResolver

   */

  virtual TraceResolver *DoCreateTraceResolver (TraceContext const &context);

  /**

   * Aborts the transmission of the current packet

   *

   * If the net device has tried to transmit a packet for more times

   * than the maximum allowed number of retries (channel always busy)

   * then the packet is dropped.

   *

   */

  void TransmitAbort (void);

  /** 

   * Device ID returned by the attached functions. It is used by the

   * mp-channel to identify each net device to make sure that only

   * active net devices are writing to the channel

   */

  uint32_t m_deviceId; 

  /**

   * Enable net device to send packets. True by default

   */

  bool m_sendEnable;

  /**

   * Enable net device to receive packets. True by default

   */

  bool m_receiveEnable;

  /**

   * Enumeration of the states of the transmit machine of the net device.

   */

  enum TxMachineState

    {

      READY, /**< The transmitter is ready to begin transmission of a packet */

      BUSY,  /**< The transmitter is busy transmitting a packet */

      GAP,    /**< The transmitter is in the interframe gap time */

      BACKOFF    /**< The transmitter is waiting for the channel to be free */

    };

  /**

   * The state of the Net Device transmit state machine.

   * @see TxMachineState

   */

  TxMachineState m_txMachineState;

  /**

   * The type of packet that should be created by the AddHeader

   * function and that should be processed by the ProcessHeader

   * function.

   */

  CsmaCdEncapsulationMode m_pktType;

  /**

   * The data rate that the Net Device uses to simulate packet transmission

   * timing.

   * @see class DataRate

   */

  DataRate m_bps;

  /**

   * The interframe gap that the Net Device uses to throttle packet

   * transmission

   * @see class Time

   */

  Time m_tInterframeGap;

  /**

   * Holds the backoff parameters and is used to calculate the next

   * backoff time to use when the channel is busy and the net device

   * is ready to transmit

   */

  Backoff m_backoff;

  /**

   * Next packet that will be transmitted (if transmitter is not

   * currently transmitting) or packet that is currently being

   * transmitted.

   */

  Packet m_currentPkt;

  /**

   * The CsmaCdChannel to which this CsmaCdNetDevice has been

   * attached.

   * @see class CsmaCdChannel

   */

  Ptr<CsmaCdChannel> m_channel;

  /**

   * The Queue which this CsmaCdNetDevice uses as a packet source.

   * Management of this Queue has been delegated to the CsmaCdNetDevice

   * and it has the responsibility for deletion.

   * @see class Queue

   * @see class DropTailQueue

   */

  Ptr<Queue> m_queue;

  /**

   * NOT TESTED

   * The trace source for the packet reception events that the device can

   * fire.

   *

   * @see class CallBackTraceSource

   * @see class TraceResolver

   */

  CallbackTraceSource<Packet &> m_rxTrace;

  CallbackTraceSource<Packet &> m_dropTrace;

};

}; // namespace ns3

#endif // CSMA_CD_NET_DEVICE_H