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

/*

 * Copyright (c) 2003,2007 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 "onoe-wifi-manager.h"

#include "ns3/simulator.h"

#include "ns3/log.h"

#include "ns3/uinteger.h"

NS_LOG_COMPONENT_DEFINE ("OnoeWifiRemoteStation");

namespace ns3 {

struct OnoeWifiRemoteStation : public WifiRemoteStation

{

  Time m_nextModeUpdate;

  uint32_t m_shortRetry;

  uint32_t m_longRetry;

  uint32_t m_tx_ok;

  uint32_t m_tx_err;

  uint32_t m_tx_retr;

  uint32_t m_tx_upper;

  uint32_t m_txrate;

};

NS_OBJECT_ENSURE_REGISTERED (OnoeWifiManager);

TypeId

OnoeWifiManager::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::OnoeWifiManager")

    .SetParent<WifiRemoteStationManager> ()

    .AddConstructor<OnoeWifiManager> ()

    .AddAttribute ("UpdatePeriod",

                   "The interval between decisions about rate control changes",

                   TimeValue (Seconds (1.0)),

                   MakeTimeAccessor (&OnoeWifiManager::m_updatePeriod),

                   MakeTimeChecker ())

    .AddAttribute ("RaiseThreshold", "Attempt to raise the rate if we hit that threshold",

                   UintegerValue (10),

                   MakeUintegerAccessor (&OnoeWifiManager::m_raiseThreshold),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("AddCreditThreshold", "Add credit threshold",

                   UintegerValue (10),

                   MakeUintegerAccessor (&OnoeWifiManager::m_addCreditThreshold),

                   MakeUintegerChecker<uint32_t> ())

    ;

  return tid;

}

OnoeWifiManager::OnoeWifiManager ()

{}

WifiRemoteStation *

OnoeWifiManager::DoCreateStation (void) const

{

  OnoeWifiRemoteStation *station = new OnoeWifiRemoteStation ();

  station->m_nextModeUpdate = Simulator::Now () + m_updatePeriod;

  station->m_shortRetry = 0;

  station->m_longRetry = 0;

  station->m_tx_ok = 0;

  station->m_tx_err = 0;

  station->m_tx_retr = 0;

  station->m_tx_upper = 0;

  station->m_txrate = 0;

  return station;

}

void 

OnoeWifiManager::DoReportRxOk (WifiRemoteStation *station,

                                     double rxSnr, WifiMode txMode)

{}

void 

OnoeWifiManager::DoReportRtsFailed (WifiRemoteStation *st)

{

  OnoeWifiRemoteStation *station = (OnoeWifiRemoteStation *)st;

  station->m_shortRetry++;

}

void 

OnoeWifiManager::DoReportDataFailed (WifiRemoteStation *st)

{

  OnoeWifiRemoteStation *station = (OnoeWifiRemoteStation *)st;

  station->m_longRetry++;

}

void 

OnoeWifiManager::DoReportRtsOk (WifiRemoteStation *station,

                                      double ctsSnr, WifiMode ctsMode, double rtsSnr)

{}

void 

OnoeWifiManager::DoReportDataOk (WifiRemoteStation *st,

                                       double ackSnr, WifiMode ackMode, double dataSnr)

{

  OnoeWifiRemoteStation *station = (OnoeWifiRemoteStation *)st;

  UpdateRetry (station);

  station->m_tx_ok++;

}

void 

OnoeWifiManager::DoReportFinalRtsFailed (WifiRemoteStation *st)

{

  OnoeWifiRemoteStation *station = (OnoeWifiRemoteStation *)st;

  UpdateRetry (station);

  station->m_tx_err++;

}

void 

OnoeWifiManager::DoReportFinalDataFailed (WifiRemoteStation *st)

{

  OnoeWifiRemoteStation *station = (OnoeWifiRemoteStation *)st;

  UpdateRetry (station);

  station->m_tx_err++;

}

void

OnoeWifiManager::UpdateRetry (OnoeWifiRemoteStation *station)

{

  station->m_tx_retr += station->m_shortRetry + station->m_longRetry;

  station->m_shortRetry = 0;

  station->m_longRetry = 0;

}

void

OnoeWifiManager::UpdateMode (OnoeWifiRemoteStation *station)

{

  if (Simulator::Now () < station->m_nextModeUpdate)

    {

      return;

    }

  station->m_nextModeUpdate = Simulator::Now () + m_updatePeriod;

  /**

   * The following 20 lines of code were copied from the Onoe

   * rate control kernel module used in the madwifi driver.

   */

  int dir = 0, enough;

  uint32_t nrate;

  enough = (station->m_tx_ok + station->m_tx_err >= 10);

  /* no packet reached -> down */

  if (station->m_tx_err > 0 && station->m_tx_ok == 0)

    dir = -1;

  /* all packets needs retry in average -> down */

  if (enough && station->m_tx_ok < station->m_tx_retr)

    dir = -1;

  /* no error and less than rate_raise% of packets need retry -> up */

  if (enough && station->m_tx_err == 0 &&

      station->m_tx_retr < (station->m_tx_ok * m_addCreditThreshold) / 100)

    dir = 1;

  NS_LOG_DEBUG (this << " ok " << station->m_tx_ok << " err " << station->m_tx_err << " retr " << station->m_tx_retr <<

                " upper " << station->m_tx_upper << " dir " << dir);

  nrate = station->m_txrate;

  switch (dir) {

  case 0:

    if (enough && station->m_tx_upper > 0)

      station->m_tx_upper--;

    break;

  case -1:

    if (nrate > 0) {

      nrate--;

    }

    station->m_tx_upper = 0;

    break;

  case 1:

    /* raise rate if we hit rate_raise_threshold */

    if (++station->m_tx_upper < m_raiseThreshold)

      break;

    station->m_tx_upper = 0;

    if (nrate + 1 < GetNSupported (station)) {

      nrate++;

    }

    break;

  }

  if (nrate != station->m_txrate) {

    NS_ASSERT (nrate < GetNSupported (station));

    station->m_txrate = nrate;

    station->m_tx_ok = station->m_tx_err = station->m_tx_retr = station->m_tx_upper = 0;

  } else if (enough)

    station->m_tx_ok = station->m_tx_err = station->m_tx_retr = 0;

}

WifiMode 

OnoeWifiManager::DoGetDataMode (WifiRemoteStation *st,

                                      uint32_t size)

{

  OnoeWifiRemoteStation *station = (OnoeWifiRemoteStation *)st;

  UpdateMode (station);

  NS_ASSERT (station->m_txrate < GetNSupported (station));

  uint32_t rateIndex;

  if (station->m_longRetry < 4)

    {

      rateIndex = station->m_txrate;

    }

  else if (station->m_longRetry < 6)

    {

      if (station->m_txrate > 0)

        {

          rateIndex = station->m_txrate - 1;

        }

      else

        {

          rateIndex = station->m_txrate;

        }

    }

  else if (station->m_longRetry < 8)

    {

      if (station->m_txrate > 1)

        {

          rateIndex = station->m_txrate - 2;

        }

      else

        {

          rateIndex = station->m_txrate;

        }

    }

  else

    {

      if (station->m_txrate > 2)

        {

          rateIndex = station->m_txrate - 3;

        }

      else

        {

          rateIndex = station->m_txrate;

        }

    }

  return GetSupported (station, rateIndex);

}

WifiMode 

OnoeWifiManager::DoGetRtsMode (WifiRemoteStation *st)

{

  OnoeWifiRemoteStation *station = (OnoeWifiRemoteStation *)st;

  UpdateMode (station);

  // XXX: can we implement something smarter ?

  return GetSupported (station, 0);

}

bool 

OnoeWifiManager::IsLowLatency (void) const

{

  return false;

}

} // namespace ns3