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

/*

 * Copyright (c) 2004,2005,2006 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>

 */

#include "mac-stations.h"

#include "arf-mac-stations.h"

#include "ns3/assert.h"

#include "ns3/log.h"

#include "ns3/default-value.h"

NS_LOG_COMPONENT_DEFINE ("Arf");

namespace ns3 {

ArfMacStation::ArfMacStation (ArfMacStations *stations,

                              int minTimerTimeout,

                              int minSuccessThreshold)

  : m_stations (stations)

{

  m_minTimerTimeout = minTimerTimeout;

  m_minSuccessThreshold = minSuccessThreshold;

  m_successThreshold = m_minSuccessThreshold;

  m_timerTimeout = m_minTimerTimeout;

  m_rate = GetMinRate ();

  m_success = 0;

  m_failed = 0;

  m_recovery = false;

  m_retry = 0;

  m_timer = 0;

}

ArfMacStation::~ArfMacStation ()

{}

uint32_t

ArfMacStation::GetMaxRate (void)

{

  return GetNSupportedModes ();

}

uint32_t

ArfMacStation::GetMinRate (void)

{

  return 0;

}

bool 

ArfMacStation::NeedRecoveryFallback (void)

{

  if (m_retry == 1) 

    {

      return true;

    } 

  else 

    {

      return false;

    }

}

bool 

ArfMacStation::NeedNormalFallback (void)

{

  int retryMod = (m_retry - 1) % 2;

  if (retryMod == 1) 

    {

      return true;

    } 

  else 

    {

      return false;

    }

}

void 

ArfMacStation::ReportRtsFailed (void)

{}

/**

 * It is important to realize that "recovery" mode starts after failure of

 * the first transmission after a rate increase and ends at the first successful

 * transmission. Specifically, recovery mode transcends retransmissions boundaries.

 * Fundamentally, ARF handles each data transmission independently, whether it

 * is the initial transmission of a packet or the retransmission of a packet.

 * The fundamental reason for this is that there is a backoff between each data

 * transmission, be it an initial transmission or a retransmission.

 */

void 

ArfMacStation::ReportDataFailed (void)

{

  m_timer++;

  m_failed++;

  m_retry++;

  m_success = 0;

  if (m_recovery) 

    {

      NS_ASSERT (m_retry >= 1);

      if (NeedRecoveryFallback ()) 

        {

          ReportRecoveryFailure ();

          if (m_rate != GetMinRate ()) 

            {

              m_rate--;

            }

        }

      m_timer = 0;

    } 

  else 

    {

      NS_ASSERT (m_retry >= 1);

      if (NeedNormalFallback ()) 

        {

          ReportFailure ();

          if (m_rate != GetMinRate ()) 

            {

              m_rate--;

            }

        }

      if (m_retry >= 2) 

        {

          m_timer = 0;

        }

    }

}

void 

ArfMacStation::ReportRxOk (double rxSnr, WifiMode txMode)

{}

void ArfMacStation::ReportRtsOk (double ctsSnr, WifiMode ctsMode, double rtsSnr)

{

  NS_LOG_DEBUG ("self="<<this<<" rts ok");

}

void ArfMacStation::ReportDataOk (double ackSnr, WifiMode ackMode, double dataSnr)

{

  m_timer++;

  m_success++;

  m_failed = 0;

  m_recovery = false;

  m_retry = 0;

  NS_LOG_DEBUG ("self="<<this<<" data ok success="<<m_success<<", timer="<<m_timer);

  if ((m_success == GetSuccessThreshold () ||

       m_timer == GetTimerTimeout ()) &&

      (m_rate < (GetMaxRate () - 1))) 

    {

      NS_LOG_DEBUG ("self="<<this<<" inc rate");

      m_rate++;

      m_timer = 0;

      m_success = 0;

      m_recovery = true;

    }

}

void 

ArfMacStation::ReportFinalRtsFailed (void)

{}

void 

ArfMacStation::ReportFinalDataFailed (void)

{}

WifiMode

ArfMacStation::DoGetDataMode (uint32_t size)

{

  return GetSupportedMode (m_rate);

}

WifiMode

ArfMacStation::DoGetRtsMode (void)

{

  // XXX: we could/should implement the Arf algorithm for

  // RTS only by picking a single rate within the BasicRateSet.

  return GetSupportedMode (0);

}

void ArfMacStation::ReportRecoveryFailure (void)

{}

void ArfMacStation::ReportFailure (void)

{}

uint32_t ArfMacStation::GetMinTimerTimeout (void)

{

  return m_minTimerTimeout;

}

uint32_t ArfMacStation::GetMinSuccessThreshold (void)

{

  return m_minSuccessThreshold;

}

uint32_t ArfMacStation::GetTimerTimeout (void)

{

  return m_timerTimeout;

}

uint32_t ArfMacStation::GetSuccessThreshold (void)

{

  return m_successThreshold;

}

void ArfMacStation::SetTimerTimeout (uint32_t timerTimeout)

{

  NS_ASSERT (timerTimeout >= m_minTimerTimeout);

  m_timerTimeout = timerTimeout;

}

void ArfMacStation::SetSuccessThreshold (uint32_t successThreshold)

{

  NS_ASSERT (successThreshold >= m_minSuccessThreshold);

  m_successThreshold = successThreshold;

}

ArfMacStations *

ArfMacStation::GetStations (void) const

{

  return m_stations;

}

ArfMacStations::ArfMacStations (WifiMode defaultTxMode, uint32_t timerThreshold, uint32_t successThreshold)

  : MacStations (defaultTxMode),

    m_timerThreshold (timerThreshold),

    m_successThreshold (successThreshold)

{}

ArfMacStations::~ArfMacStations ()

{}

MacStation *

ArfMacStations::CreateStation (void)

{

  return new ArfMacStation (this, m_timerThreshold, m_successThreshold);

}

} // namespace ns3