A Discrete-Event Network Simulator
API
lr-wpan-mac-trailer.cc
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1 /* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
2 /*
3  * Copyright (c) 2011 The Boeing Company
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  * Author:
19  * kwong yin <kwong-sang.yin@boeing.com>
20  * Sascha Alexander Jopen <jopen@cs.uni-bonn.de>
21  * Erwan Livolant <erwan.livolant@inria.fr>
22  */
23 #include "lr-wpan-mac-trailer.h"
24 #include <ns3/packet.h>
25 
26 namespace ns3 {
27 
28 NS_OBJECT_ENSURE_REGISTERED (LrWpanMacTrailer);
29 
31 
33  : m_fcs (0),
34  m_calcFcs (false)
35 {
36 }
37 
38 TypeId
40 {
41  static TypeId tid = TypeId ("ns3::LrWpanMacTrailer")
42  .SetParent<Trailer> ()
43  .SetGroupName ("LrWpan")
44  .AddConstructor<LrWpanMacTrailer> ()
45  ;
46  return tid;
47 }
48 
49 TypeId
51 {
52  return GetTypeId ();
53 }
54 
55 void
56 LrWpanMacTrailer::Print (std::ostream &os) const
57 {
58  os << " FCS = " << m_fcs;
59 }
60 
61 uint32_t
63 {
65 }
66 
67 void
69 {
71  start.WriteU16 (m_fcs);
72 }
73 
74 uint32_t
76 {
78  m_fcs = start.ReadU16 ();
79 
81 }
82 
83 uint16_t
85 {
86  return m_fcs;
87 }
88 
89 void
91 {
92  if (m_calcFcs)
93  {
94  uint16_t size = p->GetSize ();
95  uint8_t *serial_packet = new uint8_t[size];
96 
97  p->CopyData (serial_packet, size);
98 
99  m_fcs = GenerateCrc16 (serial_packet, size);
100  delete[] serial_packet;
101  }
102 }
103 
104 /* Be sure to have removed the trailer and only the trailer
105  * from the packet before to use CheckFcs */
106 bool
108 {
109  if (!m_calcFcs)
110  {
111  return true;
112  }
113  else
114  {
115  uint16_t checkFcs;
116  uint16_t size = p->GetSize ();
117  uint8_t *serial_packet = new uint8_t[size];
118 
119  p->CopyData (serial_packet, size);
120 
121  checkFcs = GenerateCrc16 (serial_packet, size);
122  delete[] serial_packet;
123  return (checkFcs == GetFcs ());
124  }
125 }
126 
127 void
129 {
130  m_calcFcs = enable;
131  if (!enable)
132  {
133  m_fcs = 0;
134  }
135 }
136 
137 bool
139 {
140  return m_calcFcs;
141 }
142 
143 uint16_t
144 LrWpanMacTrailer::GenerateCrc16 (uint8_t *data, int length)
145 {
146  int i;
147  uint16_t accumulator = 0;
148 
149  for (i = 0; i < length; ++i)
150  {
151  accumulator ^= *data;
152  accumulator = (accumulator >> 8) | (accumulator << 8);
153  accumulator ^= (accumulator & 0xff00) << 4;
154  accumulator ^= (accumulator >> 8) >> 4;
155  accumulator ^= (accumulator & 0xff00) >> 5;
156  ++data;
157  }
158  return accumulator;
159 }
160 
161 } //namespace ns3
void EnableFcs(bool enable)
Enable or disable FCS calculation for this trailer.
bool IsFcsEnabled(void)
Query if FCS calculation is enabled for this trailer.
virtual uint32_t GetSerializedSize(void) const
#define NS_OBJECT_ENSURE_REGISTERED(type)
Register an Object subclass with the TypeId system.
Definition: object-base.h:45
uint32_t GetSize(void) const
Returns the the size in bytes of the packet (including the zero-filled initial payload).
Definition: packet.h:852
virtual TypeId GetInstanceTypeId(void) const
Get the most derived TypeId for this Object.
def start()
Definition: core.py:1855
iterator in a Buffer instance
Definition: buffer.h:98
virtual uint32_t Deserialize(Buffer::Iterator start)
uint16_t GetFcs(void) const
Get this trailers FCS value.
uint8_t data[writeSize]
LrWpanMacTrailer(void)
Default constructor for a MAC trailer with disabled FCS calculation.
void SetFcs(Ptr< const Packet > p)
Calculate and set the FCS value based on the given packet.
Protocol trailer serialization and deserialization.
Definition: trailer.h:40
bool m_calcFcs
Only if m_calcFcs is true, FCS values will be calculated and used in the trailer. ...
Every class exported by the ns3 library is enclosed in the ns3 namespace.
static const uint16_t LR_WPAN_MAC_FCS_LENGTH
The length in octets of the IEEE 802.15.4 MAC FCS field.
Represent the Mac Trailer with the Frame Check Sequence field.
uint32_t CopyData(uint8_t *buffer, uint32_t size) const
Copy the packet contents to a byte buffer.
Definition: packet.cc:378
virtual void Serialize(Buffer::Iterator start) const
uint16_t GenerateCrc16(uint8_t *data, int length)
Calculate the 16-bit FCS value.
bool CheckFcs(Ptr< const Packet > p)
Check the FCS of a given packet against the FCS value stored in the trailer.
a unique identifier for an interface.
Definition: type-id.h:58
TypeId SetParent(TypeId tid)
Set the parent TypeId.
Definition: type-id.cc:915
virtual void Print(std::ostream &os) const
uint16_t m_fcs
The FCS value stored in this trailer.
static TypeId GetTypeId(void)
Get the type ID.