A Discrete-Event Network Simulator
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delay-jitter-estimation.cc
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
2 /*
3  * Copyright (c) 2007 INRIA
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation;
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17  *
18  * Authors: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
19  */
20 
21 #include "delay-jitter-estimation.h"
22 #include "ns3/tag.h"
23 #include "ns3/simulator.h"
24 #include "ns3/string.h"
25 
26 namespace ns3 {
27 
28 class DelayJitterEstimationTimestampTag : public Tag
29 {
30 public:
31  DelayJitterEstimationTimestampTag ();
32  static TypeId GetTypeId (void);
33  virtual TypeId GetInstanceTypeId (void) const;
34 
35  virtual uint32_t GetSerializedSize (void) const;
36  virtual void Serialize (TagBuffer i) const;
37  virtual void Deserialize (TagBuffer i);
38  virtual void Print (std::ostream &os) const;
39 
40  Time GetTxTime (void) const;
41 private:
42  uint64_t m_creationTime;
43 };
44 
45 DelayJitterEstimationTimestampTag::DelayJitterEstimationTimestampTag ()
46  : m_creationTime (Simulator::Now ().GetTimeStep ())
47 {
48 }
49 
50 TypeId
51 DelayJitterEstimationTimestampTag::GetTypeId (void)
52 {
53  static TypeId tid = TypeId ("anon::DelayJitterEstimationTimestampTag")
54  .SetParent<Tag> ()
55  .AddConstructor<DelayJitterEstimationTimestampTag> ()
56  .AddAttribute ("CreationTime",
57  "The time at which the timestamp was created",
58  StringValue ("0.0s"),
59  MakeTimeAccessor (&DelayJitterEstimationTimestampTag::GetTxTime),
60  MakeTimeChecker ())
61  ;
62  return tid;
63 }
64 TypeId
65 DelayJitterEstimationTimestampTag::GetInstanceTypeId (void) const
66 {
67  return GetTypeId ();
68 }
69 
70 uint32_t
71 DelayJitterEstimationTimestampTag::GetSerializedSize (void) const
72 {
73  return 8;
74 }
75 void
76 DelayJitterEstimationTimestampTag::Serialize (TagBuffer i) const
77 {
78  i.WriteU64 (m_creationTime);
79 }
80 void
81 DelayJitterEstimationTimestampTag::Deserialize (TagBuffer i)
82 {
83  m_creationTime = i.ReadU64 ();
84 }
85 void
86 DelayJitterEstimationTimestampTag::Print (std::ostream &os) const
87 {
88  os << "CreationTime=" << m_creationTime;
89 }
90 Time
91 DelayJitterEstimationTimestampTag::GetTxTime (void) const
92 {
93  return TimeStep (m_creationTime);
94 }
95 
96 DelayJitterEstimation::DelayJitterEstimation ()
97  : m_previousRx (Simulator::Now ()),
98  m_previousRxTx (Simulator::Now ()),
99  m_jitter (0),
100  m_delay (Seconds (0.0))
101 {
102 }
103 void
104 DelayJitterEstimation::PrepareTx (Ptr<const Packet> packet)
105 {
106  DelayJitterEstimationTimestampTag tag;
107  packet->AddByteTag (tag);
108 }
109 void
110 DelayJitterEstimation::RecordRx (Ptr<const Packet> packet)
111 {
112  DelayJitterEstimationTimestampTag tag;
113  bool found;
114  found = packet->FindFirstMatchingByteTag (tag);
115  if (!found)
116  {
117  return;
118  }
119  tag.GetTxTime ();
120 
121  Time delta = (Simulator::Now () - m_previousRx) - (tag.GetTxTime () - m_previousRxTx);
122  m_jitter += (Abs (delta) - m_jitter) / 16;
123  m_previousRx = Simulator::Now ();
124  m_previousRxTx = tag.GetTxTime ();
125  m_delay = Simulator::Now () - tag.GetTxTime ();
126 }
127 
128 Time
129 DelayJitterEstimation::GetLastDelay (void) const
130 {
131  return m_delay;
132 }
133 uint64_t
134 DelayJitterEstimation::GetLastJitter (void) const
135 {
136  return m_jitter.GetHigh ();
137 }
138 
139 } // namespace ns3