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

/*

 * Copyright (c) 2007 University of Washington

 * 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: Craig Dowell <craigdo@ee.washington.edu>

 */

#include "point-to-point-channel.h"

#include "point-to-point-net-device.h"

#include "ns3/packet.h"

#include "ns3/simulator.h"

#include "ns3/log.h"

NS_LOG_COMPONENT_DEFINE ("PointToPointChannel");

namespace ns3 {

//

// By default, you get a channel with the name "PointToPoint Channel" that 

// has an "infitely" fast transmission speed and zero delay.

PointToPointChannel::PointToPointChannel()

: 

  Channel ("PointToPoint Channel"), 

  m_bps (DataRate(0xffffffff)),

  m_delay (Seconds(0)),

  m_nDevices(0)

{

  NS_LOG_FUNCTION;

}

PointToPointChannel::PointToPointChannel(

  const DataRate& bps, 

  const Time& delay)

: 

  Channel ("PointToPoint Channel"), 

  m_bps (bps),

  m_delay (delay),

  m_nDevices(0)

{

  NS_LOG_FUNCTION;

}

PointToPointChannel::PointToPointChannel(

  const std::string& name,

  const DataRate& bps, 

  const Time& delay)

: 

  Channel (name),

  m_bps (bps), 

  m_delay (delay),

  m_nDevices(0)

{

  NS_LOG_FUNCTION;

}

void

PointToPointChannel::Attach(Ptr<PointToPointNetDevice> device)

{

  NS_LOG_FUNCTION;

  NS_ASSERT(m_nDevices < N_DEVICES && "Only two devices permitted");

  NS_ASSERT(device != 0);

  m_link[m_nDevices++].m_src = device;

//

// If we have both devices connected to the channel, then finish introducing

// the two halves and set the links to IDLE.

//

  if (m_nDevices == N_DEVICES)

    {

      m_link[0].m_dst = m_link[1].m_src;

      m_link[1].m_dst = m_link[0].m_src;

      m_link[0].m_state = IDLE;

      m_link[1].m_state = IDLE;

    }

}

bool

PointToPointChannel::TransmitStart(Packet& p,

                                        Ptr<PointToPointNetDevice> src,

                                        const Time& txTime)

{

  NS_LOG_FUNCTION;

  NS_LOG_LOGIC ("UID is " << p.GetUid () << ")");

  NS_ASSERT(m_link[0].m_state != INITIALIZING);

  NS_ASSERT(m_link[1].m_state != INITIALIZING);

  uint32_t wire = src == m_link[0].m_src ? 0 : 1;

  // Here we schedule the packet receive event at the receiver,

  // which simplifies this model quite a bit.  The channel just

  // adds the propagation delay time

  Simulator::Schedule (txTime + m_delay,

                       &PointToPointNetDevice::Receive,

                       m_link[wire].m_dst, p);

  return true;

}

uint32_t 

PointToPointChannel::GetNDevices (void) const

{

  NS_LOG_FUNCTION;

  return m_nDevices;

}

Ptr<PointToPointNetDevice>

PointToPointChannel::GetDevice (uint32_t i) const

{

  NS_LOG_FUNCTION;

  NS_ASSERT(i < 2);

  return m_link[i].m_src;

}

const DataRate&

PointToPointChannel::GetDataRate (void)

{

  NS_LOG_FUNCTION;

  return m_bps;

}

const Time&

PointToPointChannel::GetDelay (void)

{

  NS_LOG_FUNCTION;

  return m_delay;

}

Ptr<NetDevice>

PointToPointChannel::DoGetDevice (uint32_t i) const

{

  NS_LOG_FUNCTION;

  return GetDevice (i);

}

} // namespace ns3