--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/common/byte-tag-list.h Wed Jun 03 08:49:40 2009 +0200
@@ -0,0 +1,170 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2008 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>
+ */
+#ifndef BYTE_TAG_LIST_H
+#define BYTE_TAG_LIST_H
+
+#include <stdint.h>
+#include "ns3/type-id.h"
+#include "tag-buffer.h"
+
+namespace ns3 {
+
+struct ByteTagListData;
+
+/**
+ * \ingroup packet
+ *
+ * \brief keep track of the tags stored in a packet.
+ *
+ * This class is mostly private to the Packet implementation and users
+ * should never have to access it directly.
+ *
+ * \internal
+ * The implementation of this class is a bit tricky so, there are a couple
+ * of things to keep in mind here:
+ *
+ * - it stores all tags in a single byte buffer: each tag is stored
+ * as 4 32bit integers (TypeId, tag data size, start, end) followed
+ * by the tag data as generated by Tag::Serialize.
+ *
+ * - the struct ByteTagListData structure which contains the tag byte buffer
+ * is shared and, thus, reference-counted. This data structure is unshared
+ * as-needed to emulate COW semantics.
+ *
+ * - each tag tags a unique set of bytes identified by the pair of offsets
+ * (start,end). These offsets are provided by Buffer::GetCurrentStartOffset
+ * and Buffer::GetCurrentEndOffset which means that they are relative to
+ * the start of the 'virtual byte buffer' as explained in the documentation
+ * for the ns3::Buffer class. Whenever the origin of the offset of the Buffer
+ * instance associated to this ByteTagList instance changes, the Buffer class
+ * reports this to its container Packet class as a bool return value
+ * in Buffer::AddAtStart and Buffer::AddAtEnd. In both cases, when this happens
+ * the Packet class calls ByteTagList::AddAtEnd and ByteTagList::AddAtStart to update
+ * the byte offsets of each tag in the ByteTagList.
+ *
+ * - whenever bytes are removed from the packet byte buffer, the ByteTagList offsets
+ * are never updated because we rely on the fact that they will be updated in
+ * either the next call to Packet::AddHeader or Packet::AddTrailer or when
+ * the user iterates the tag list with Packet::GetTagIterator and
+ * TagIterator::Next.
+ */
+class ByteTagList
+{
+public:
+
+ class Iterator
+ {
+ public:
+ struct Item
+ {
+ TypeId tid;
+ uint32_t size;
+ int32_t start;
+ int32_t end;
+ TagBuffer buf;
+ Item (TagBuffer buf);
+ private:
+ friend class ByteTagList;
+ friend class ByteTagList::Iterator;
+ };
+ bool HasNext (void) const;
+ struct ByteTagList::Iterator::Item Next (void);
+ uint32_t GetOffsetStart (void) const;
+ private:
+ friend class ByteTagList;
+ Iterator (uint8_t *start, uint8_t *end, int32_t offsetStart, int32_t offsetEnd);
+ void PrepareForNext (void);
+ uint8_t *m_current;
+ uint8_t *m_end;
+ int32_t m_offsetStart;
+ int32_t m_offsetEnd;
+ uint32_t m_nextTid;
+ uint32_t m_nextSize;
+ int32_t m_nextStart;
+ int32_t m_nextEnd;
+ };
+
+ ByteTagList ();
+ ByteTagList (const ByteTagList &o);
+ ByteTagList &operator = (const ByteTagList &o);
+ ~ByteTagList ();
+
+ /**
+ * \param tid the typeid of the tag added
+ * \param bufferSize the size of the tag when its serialization will
+ * be completed. Typically, the return value of Tag::GetSerializedSize
+ * \param start offset which uniquely identifies the first byte tagged by this tag.
+ * \param end offset which uniquely identifies the last byte tagged by this tag.
+ * \returns a buffer which can be used to write the tag data.
+ *
+ *
+ */
+ TagBuffer Add (TypeId tid, uint32_t bufferSize, int32_t start, int32_t end);
+
+ /**
+ * \param o the other list of tags to aggregate.
+ *
+ * Aggregate the two lists of tags.
+ */
+ void Add (const ByteTagList &o);
+
+ void RemoveAll (void);
+
+ /**
+ * \param offsetStart the offset which uniquely identifies the first data byte
+ * present in the byte buffer associated to this ByteTagList.
+ * \param offsetEnd the offset which uniquely identifies the last data byte
+ * present in the byte buffer associated to this ByteTagList.
+ * \returns an iterator
+ *
+ * The returned iterator will allow you to loop through the set of tags present
+ * in this list: the boundaries of each tag as reported by their start and
+ * end offsets will be included within the input offsetStart and offsetEnd.
+ */
+ ByteTagList::Iterator Begin (int32_t offsetStart, int32_t offsetEnd) const;
+
+ /**
+ * Adjust the offsets stored internally by the adjustment delta and
+ * make sure that all offsets are smaller than appendOffset which represents
+ * the location where new bytes have been added to the byte buffer.
+ */
+ void AddAtEnd (int32_t adjustment, int32_t appendOffset);
+ /**
+ * Adjust the offsets stored internally by the adjustment delta and
+ * make sure that all offsets are bigger than prependOffset which represents
+ * the location where new bytes have been added to the byte buffer.
+ */
+ void AddAtStart (int32_t adjustment, int32_t prependOffset);
+
+private:
+ bool IsDirtyAtEnd (int32_t appendOffset);
+ bool IsDirtyAtStart (int32_t prependOffset);
+ ByteTagList::Iterator BeginAll (void) const;
+
+ struct ByteTagListData *Allocate (uint32_t size);
+ void Deallocate (struct ByteTagListData *data);
+
+ uint16_t m_used;
+ struct ByteTagListData *m_data;
+};
+
+} // namespace ns3
+
+#endif /* BYTE_TAG_LIST_H */