src/devices/point-to-point/p2p-net-device.cc
changeset 972 6946c8237a73
parent 971 7aba0cf0df19
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/devices/point-to-point/p2p-net-device.cc	Fri Jul 27 20:17:23 2007 +0200
@@ -0,0 +1,221 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2005,2006 INRIA
+ * 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>
+ * Revised: George Riley <riley@ece.gatech.edu>
+ */
+
+#include <iostream>
+#include <cassert>
+#include "ns3/debug.h"
+#include "ns3/queue.h"
+#include "ns3/simulator.h"
+#include "ns3/composite-trace-resolver.h"
+#include "p2p-net-device.h"
+#include "p2p-channel.h"
+
+NS_DEBUG_COMPONENT_DEFINE ("PointToPointNetDevice");
+
+namespace ns3 {
+
+DataRateDefaultValue PointToPointNetDevice::g_defaultRate(
+           "PointToPointLinkDataRate", 
+           "The default data rate for point to point links",
+           DataRate ("10Mb/s"));
+
+  PointToPointNetDevice::PointToPointNetDevice (Ptr<Node> node,
+                                                const DataRate& rate) 
+: 
+  NetDevice(node, MacAddress (6)), 
+  m_txMachineState (READY),
+  m_bps (rate),
+  m_tInterframeGap (Seconds(0)),
+  m_channel (0), 
+  m_queue (0),
+  m_rxTrace ()
+{
+  NS_DEBUG ("PointToPointNetDevice::PointToPointNetDevice (" << node << ")");
+
+  // BUGBUG FIXME
+  //
+  // You _must_ support broadcast to get any sort of packet from the ARP layer.
+  EnableBroadcast (MacAddress ("ff:ff:ff:ff:ff:ff"));
+  EnableMulticast();
+  EnablePointToPoint();
+}
+
+PointToPointNetDevice::~PointToPointNetDevice()
+{
+  NS_DEBUG ("PointToPointNetDevice::~PointToPointNetDevice ()");
+  m_queue = 0;
+}
+
+void PointToPointNetDevice::DoDispose()
+{
+  m_channel = 0;
+  NetDevice::DoDispose ();
+}
+
+
+void PointToPointNetDevice::SetDataRate(const DataRate& bps)
+{
+  m_bps = bps;
+}
+
+void PointToPointNetDevice::SetInterframeGap(const Time& t)
+{
+  m_tInterframeGap = t;
+}
+
+bool PointToPointNetDevice::SendTo (Packet& p, const MacAddress& dest)
+{
+  NS_DEBUG ("PointToPointNetDevice::SendTo (" << &p << ", " << &dest << ")");
+  NS_DEBUG ("PointToPointNetDevice::SendTo (): UID is " << p.GetUid () << ")");
+
+  // GFR Comment. Why is this an assertion? Can't a link legitimately
+  // "go down" during the simulation?  Shouldn't we just wait for it
+  // to come back up?
+  NS_ASSERT (IsLinkUp ());
+
+//
+// This class simulates a point to point device.  In the case of a serial
+// link, this means that we're simulating something like a UART.
+//
+//
+// If there's a transmission in progress, we enque the packet for later
+// trnsmission; otherwise we send it now.
+    if (m_txMachineState == READY) 
+      {
+        return TransmitStart (p);
+      }
+    else
+      {
+        return m_queue->Enqueue(p);
+      }
+}
+
+  bool
+PointToPointNetDevice::TransmitStart (Packet &p)
+{
+  NS_DEBUG ("PointToPointNetDevice::TransmitStart (" << &p << ")");
+  NS_DEBUG (
+    "PointToPointNetDevice::TransmitStart (): UID is " << p.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 the transmission is complete.
+//
+  NS_ASSERT_MSG(m_txMachineState == READY, "Must be READY to transmit");
+  m_txMachineState = BUSY;
+  Time txTime = Seconds (m_bps.CalculateTxTime(p.GetSize()));
+  Time txCompleteTime = txTime + m_tInterframeGap;
+
+  NS_DEBUG ("PointToPointNetDevice::TransmitStart (): " <<
+    "Schedule TransmitCompleteEvent in " << 
+    txCompleteTime.GetSeconds () << "sec");
+  // Schedule the tx complete event
+  Simulator::Schedule (txCompleteTime, 
+                       &PointToPointNetDevice::TransmitComplete, 
+                       this);
+  return m_channel->TransmitStart(p, this, txTime); 
+}
+
+void PointToPointNetDevice::TransmitComplete (void)
+{
+  NS_DEBUG ("PointToPointNetDevice::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
+// get the next packet from the queue.  If the queue is empty, we are
+// done, otherwise transmit the next packet.
+//
+  NS_ASSERT_MSG(m_txMachineState == BUSY, "Must be BUSY if transmitting");
+  m_txMachineState = READY;
+  Packet p;
+  if (!m_queue->Dequeue(p)) return; // Nothing to do at this point
+  TransmitStart(p);
+}
+
+TraceResolver* PointToPointNetDevice::DoCreateTraceResolver (
+                                      TraceContext const &context)
+{
+  CompositeTraceResolver *resolver = new CompositeTraceResolver (context);
+  resolver->Add ("queue", 
+                 MakeCallback (&Queue::CreateTraceResolver, PeekPointer (m_queue)),
+                 PointToPointNetDevice::QUEUE);
+  resolver->Add ("rx",
+                 m_rxTrace,
+                 PointToPointNetDevice::RX);
+  return resolver;
+}
+
+bool PointToPointNetDevice::Attach (Ptr<PointToPointChannel> ch)
+{
+  NS_DEBUG ("PointToPointNetDevice::Attach (" << &ch << ")");
+
+  m_channel = ch;
+
+  m_channel->Attach(this);
+  m_bps = m_channel->GetDataRate ();
+  // GFR Comment.  Below is definitely wrong.  Interframe gap
+  // is unrelated to channel delay.
+  //m_tInterframeGap = m_channel->GetDelay ();
+
+  /* 
+   * For now, this device is up whenever a channel is attached to it.
+   * In fact, it should become up only when the second device
+   * is attached to the channel. So, there should be a way for
+   * a PointToPointChannel to notify both of its attached devices
+   * that the channel is 'complete', hence that the devices are
+   * up, hence that they can call NotifyLinkUp. 
+   */
+  NotifyLinkUp ();
+  return true;
+}
+
+void PointToPointNetDevice::AddQueue (Ptr<Queue> q)
+{
+  NS_DEBUG ("PointToPointNetDevice::AddQueue (" << q << ")");
+
+  m_queue = q;
+}
+
+void PointToPointNetDevice::Receive (Packet& p)
+{
+  NS_DEBUG ("PointToPointNetDevice::Receive (" << &p << ")");
+
+  m_rxTrace (p);
+  ForwardUp (p);
+}
+
+Ptr<Queue> PointToPointNetDevice::GetQueue(void) const 
+{ 
+    return m_queue;
+}
+
+Ptr<Channel> PointToPointNetDevice::DoGetChannel(void) const 
+{ 
+    return m_channel;
+}
+
+bool PointToPointNetDevice::DoNeedsArp (void) const
+{
+  return false;
+}
+
+} // namespace ns3