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

/*

 * Copyright (c) 2007 Emmanuelle Laprise

 * All rights reserved.

 *

 * 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>

 */

#include <iostream>

#include <cassert>

#include "ns3/debug.h"

#include "ns3/queue.h"

#include "ns3/simulator.h"

#include "ns3/composite-trace-resolver.h"

#include "csma-cd-net-device.h"

#include "csma-cd-channel.h"

#include "ns3/ethernet-header.h"

#include "ns3/ethernet-trailer.h"

#include "ns3/llc-snap-header.h"

NS_DEBUG_COMPONENT_DEFINE ("CsmaCdNetDevice");

namespace ns3 {

CsmaCdNetDevice::CsmaCdNetDevice (Ptr<Node> node, Eui48Address addr, 

                                  CsmaCdEncapsulationMode encapMode) 

    m_bps (DataRate (0xffffffff))

{

  NS_DEBUG ("CsmaCdNetDevice::CsmaCdNetDevice (" << node << ")");

  m_encapMode = encapMode;

  Init(true, true);

}

CsmaCdNetDevice::CsmaCdNetDevice (Ptr<Node> node, Eui48Address addr, 

                                  CsmaCdEncapsulationMode encapMode,

                                  bool sendEnable, bool receiveEnable) 

    m_bps (DataRate (0xffffffff))

{

  NS_DEBUG ("CsmaCdNetDevice::CsmaCdNetDevice (" << node << ")");

  m_encapMode = encapMode;

  Init(sendEnable, receiveEnable);

}

CsmaCdNetDevice::~CsmaCdNetDevice()

{

  NS_DEBUG ("CsmaCdNetDevice::~CsmaCdNetDevice ()");

  m_queue = 0;

}

void 

CsmaCdNetDevice::DoDispose ()

{

  m_channel = 0;

  NetDevice::DoDispose ();

}

//

// Assignment operator for CsmaCdNetDevice.

//

// This uses the non-obvious trick of taking the source net device passed by

// value instead of by reference.  This causes the copy constructor to be

// invoked (where the real work is done -- see above).  All we have to do

// here is to return the newly constructed net device.

//

/*

CsmaCdNetDevice&

CsmaCdNetDevice::operator= (const CsmaCdNetDevice nd)

{

  NS_DEBUG ("CsmaCdNetDevice::operator= (" << &nd << ")");

  return *this;

}

*/

void 

CsmaCdNetDevice::Init(bool sendEnable, bool receiveEnable)

{

  m_txMachineState = READY;

  m_tInterframeGap = Seconds(0);

  m_channel = 0; 

  m_queue = 0;

  EnableMulticast();

  EnablePointToPoint();

  SetSendEnable (sendEnable);

  SetReceiveEnable (receiveEnable);

}

void

CsmaCdNetDevice::SetSendEnable (bool sendEnable)

{

  m_sendEnable = sendEnable;

}

void

CsmaCdNetDevice::SetReceiveEnable (bool receiveEnable)

{

  m_receiveEnable = receiveEnable;

}

bool

CsmaCdNetDevice::IsSendEnabled (void)

{

  return (m_sendEnable);

}

bool

CsmaCdNetDevice::IsReceiveEnabled (void)

{

  return (m_receiveEnable);

}

void 

CsmaCdNetDevice::SetDataRate (DataRate bps)

{

  m_bps = bps;

}

void 

CsmaCdNetDevice::SetInterframeGap (Time t)

{

  m_tInterframeGap = t;

}

void 

CsmaCdNetDevice::SetBackoffParams (Time slotTime, uint32_t minSlots, 

                                      uint32_t maxSlots, uint32_t ceiling, 

                                      uint32_t maxRetries)

{

  m_backoff.m_slotTime = slotTime;

  m_backoff.m_minSlots = minSlots;

  m_backoff.m_maxSlots = maxSlots;

  m_backoff.m_ceiling = ceiling;

  m_backoff.m_maxRetries = maxRetries;

}

void 

CsmaCdNetDevice::AddHeader (Packet& p, Eui48Address dest,

                            uint16_t protocolNumber)

{

  if (m_encapMode == RAW)

    {

      return;

    }

  EthernetHeader header (false);

  EthernetTrailer trailer;

  header.SetSource(source);

  header.SetDestination(dest);

  uint16_t lengthType = 0;

  switch (m_encapMode) 

    {

    case ETHERNET_V1:

      lengthType = p.GetSize() + header.GetSize() + trailer.GetSize();

      break;

    case IP_ARP:

      lengthType = protocolNumber;

      break;

    case LLC: {

      LlcSnapHeader llc;

      llc.SetType (protocolNumber);

      p.AddHeader (llc);

    } break;

    case RAW:

      NS_ASSERT (false);

      break;

    }

  header.SetLengthType (lengthType);

  p.AddHeader(header);

  trailer.CalcFcs(p);

  p.AddTrailer(trailer);

}

bool 

CsmaCdNetDevice::ProcessHeader (Packet& p, uint16_t & param)

{

  if (m_encapMode == RAW)

    {

      return true;

    }

  EthernetHeader header (false);

  EthernetTrailer trailer;

  p.RemoveTrailer(trailer);

  trailer.CheckFcs(p);

  p.RemoveHeader(header);

  if ((header.GetDestination() != broadcast) &&

      (header.GetDestination() != destination))

    {

      return false;

    }

  switch (m_encapMode)

    {

    case ETHERNET_V1:

    case IP_ARP:

      param = header.GetLengthType();

      break;

    case LLC: {

      LlcSnapHeader llc;

      p.RemoveHeader (llc);

      param = llc.GetType ();

    } break;

    case RAW:

      NS_ASSERT (false);

      break;

    }

  return true;

}

bool

CsmaCdNetDevice::DoNeedsArp (void) const

{

  if ((m_encapMode == IP_ARP) || (m_encapMode == LLC))

    {

      return true;

    } 

  else 

    {

      return false;

    }

}

bool

CsmaCdNetDevice::SendTo (Packet& p, const Address& dest, uint16_t protocolNumber)

{

  NS_DEBUG ("CsmaCdNetDevice::SendTo (" << &p << ")");

  NS_DEBUG ("CsmaCdNetDevice::SendTo (): UID is " << p.GetUid () << ")");

  NS_ASSERT (IsLinkUp ());

  // Only transmit if send side of net device is enabled

  if (!IsSendEnabled())

    return false;

  AddHeader(p, address, protocolNumber);

  // Place the packet to be sent on the send queue

  if (m_queue->Enqueue(p) == false )

    {

      return false;

    }

  // If the device is idle, we need to start a transmission. Otherwise,

  // the transmission will be started when the current packet finished

  // transmission (see TransmitCompleteEvent)

  if (m_txMachineState == READY) 

    {

      // Store the next packet to be transmitted

      if (m_queue->Dequeue (m_currentPkt))

        {

          TransmitStart();

        }

    }

  return true;

}

void

CsmaCdNetDevice::TransmitStart ()

{

  NS_DEBUG ("CsmaCdNetDevice::TransmitStart (" << &m_currentPkt << ")");

  NS_DEBUG ("CsmaCdNetDevice::TransmitStart (): UID is " 

            << m_currentPkt.GetUid () << ")");

//

// This function is called to start the process of transmitting a packet.

// We need to tell the channel that we've started wiggling the wire and

// schedule an event that will be executed when it's time to tell the 

// channel that we're done wiggling the wire.

//

  NS_ASSERT_MSG((m_txMachineState == READY) || (m_txMachineState == BACKOFF), 

                "Must be READY to transmit. Tx state is: " 

                << m_txMachineState);

  // Only transmit if send side of net device is enabled

  if (!IsSendEnabled())

    return;

  if (m_channel->GetState() != IDLE)

    { // Channel busy, backoff and rechedule TransmitStart()

      m_txMachineState = BACKOFF;

      if (m_backoff.MaxRetriesReached())

        { // Too many retries reached, abort transmission of packet

          TransmitAbort();

        } 

      else 

        {

          m_backoff.IncrNumRetries();

          Time backoffTime = m_backoff.GetBackoffTime();

          NS_DEBUG ("CsmaCdNetDevice::TransmitStart (): " 

                    << "Channel busy, backing off for " 

                    << backoffTime.GetSeconds () << "sec");

          Simulator::Schedule (backoffTime, 

                               &CsmaCdNetDevice::TransmitStart, 

                               this);

        }

    } 

  else 

    {

      // Channel is free, transmit packet

      m_txMachineState = BUSY;

      Time tEvent = Seconds (m_bps.CalculateTxTime(m_currentPkt.GetSize()));

      NS_DEBUG ("CsmaCdNetDevice::TransmitStart (): " <<

                "Schedule TransmitCompleteEvent in " << 

                tEvent.GetSeconds () << "sec");

      Simulator::Schedule (tEvent, 

                           &CsmaCdNetDevice::TransmitCompleteEvent, 

                           this);

      if (!m_channel->TransmitStart (m_currentPkt, m_deviceId))

        {

          NS_DEBUG ("CsmaCdNetDevice::TransmitStart (): " <<

                    "Channel transmit start did not work at " << 

                    tEvent.GetSeconds () << "sec");

          m_txMachineState = READY;

        } 

      else 

        {

          // Transmission success, reset backoff time parameters.

          m_backoff.ResetBackoffTime();

        }

    }

}

void

CsmaCdNetDevice::TransmitAbort (void)

{

  NS_DEBUG ("CsmaCdNetDevice::TransmitAbort ()");

  NS_DEBUG ("CsmaCdNetDevice::TransmitAbort (): Pkt UID is " <<

            m_currentPkt.GetUid () << ")");

  // Try to transmit a new packet

  bool found;

  found = m_queue->Dequeue (m_currentPkt);

  NS_ASSERT_MSG(found, "IsEmpty false but no Packet on queue?");

  m_backoff.ResetBackoffTime();

  m_txMachineState = READY;

  TransmitStart ();

}

void

CsmaCdNetDevice::TransmitCompleteEvent (void)

{

  NS_DEBUG ("CsmaCdNetDevice::TransmitCompleteEvent ()");

//

// This function is called to finish the  process of transmitting a packet.

// We need to tell the channel that we've stopped wiggling the wire and

// schedule an event that will be executed when it's time to re-enable

// the transmitter after the interframe gap.

//

  NS_ASSERT_MSG(m_txMachineState == BUSY, "Must be BUSY if transmitting");

  // Channel should be transmitting

  NS_ASSERT(m_channel->GetState() == TRANSMITTING);

  m_txMachineState = GAP;

  NS_DEBUG ("CsmaCdNetDevice::TransmitCompleteEvent (): Pkt UID is " << 

            m_currentPkt.GetUid () << ")");

  m_channel->TransmitEnd (); 

  NS_DEBUG (

    "CsmaCdNetDevice::TransmitCompleteEvent (): " <<

    "Schedule TransmitReadyEvent in "

    << m_tInterframeGap.GetSeconds () << "sec");

  Simulator::Schedule (m_tInterframeGap, 

                       &CsmaCdNetDevice::TransmitReadyEvent, 

                       this);

}

void

CsmaCdNetDevice::TransmitReadyEvent (void)

{

  NS_DEBUG ("CsmaCdNetDevice::TransmitReadyEvent ()");

//

// This function is called to enable the transmitter after the interframe

// gap has passed.  If there are pending transmissions, we use this opportunity

// to start the next transmit.

//

  NS_ASSERT_MSG(m_txMachineState == GAP, "Must be in interframe gap");

  m_txMachineState = READY;

  // Get the next packet from the queue for transmitting

  if (m_queue->IsEmpty())

    {

      return;

    }

  else

    {

      bool found;

      found = m_queue->Dequeue (m_currentPkt);

      NS_ASSERT_MSG(found, "IsEmpty false but no Packet on queue?");

      TransmitStart ();

    }

}

TraceResolver *

CsmaCdNetDevice::DoCreateTraceResolver (TraceContext const &context)

{

  CompositeTraceResolver *resolver = new CompositeTraceResolver (context);

  resolver->Add ("queue", 

                 MakeCallback (&Queue::CreateTraceResolver, 

                               PeekPointer (m_queue)),

                 CsmaCdNetDevice::QUEUE);

  resolver->Add ("rx",

                 m_rxTrace,

                 CsmaCdNetDevice::RX);

  return resolver;

}

bool

CsmaCdNetDevice::Attach (Ptr<CsmaCdChannel> ch)

{

  NS_DEBUG ("CsmaCdNetDevice::Attach (" << &ch << ")");

  m_channel = ch;

  m_deviceId = m_channel->Attach(this);

  m_bps = m_channel->GetDataRate ();

  m_tInterframeGap = m_channel->GetDelay ();

  /* 

   * For now, this device is up whenever a channel is attached to it.

   */

  NotifyLinkUp ();

  return true;

}

void

CsmaCdNetDevice::AddQueue (Ptr<Queue> q)

{

  NS_DEBUG ("CsmaCdNetDevice::AddQueue (" << q << ")");

  m_queue = q;

}

void

CsmaCdNetDevice::Receive (Packet& p)

{

  NS_DEBUG ("CsmaCdNetDevice::Receive UID is (" << p.GetUid() << ")");

  // Only receive if send side of net device is enabled

  if (!IsReceiveEnabled())

    return;

  uint16_t param = 0;

  Packet packet = p;

  if (ProcessHeader(packet, param))

    {

      m_rxTrace (packet);

      ForwardUp (packet, param);

    } 

  else 

    {

      m_dropTrace (packet);

    }

}

Ptr<Queue>

CsmaCdNetDevice::GetQueue(void) const 

{ 

    return m_queue;

}

Ptr<Channel>

CsmaCdNetDevice::DoGetChannel(void) const 

{ 

    return m_channel;

}

} // namespace ns3