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

//

// Copyright (c) 2006 Georgia Tech Research Corporation

//

// 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: Rajib Bhattacharjea<raj.b@gatech.edu>

//

// Georgia Tech Network Simulator - Data Descriptors

// George F. Riley.  Georgia Tech, Spring 2002

#ifndef __datapdu_h__

#define __datapdu_h__

#include "ns3/packet.h"

#include "pending-data.h"

#include "ns3/sequence-number.h"

#include "ns3/ptr.h"

namespace ns3

{

class Packet;

/**

 * \ingroup tcp

 *

 * \brief class for managing I/O between applications and TCP

 */

class PendingData {

public:

  PendingData ();

  PendingData (uint32_t s, uint8_t* d = NULL, uint32_t msg = 0, uint32_t resp = 0);

  PendingData (const std::string&); // Construct from string

  PendingData (uint8_t*, uint32_t&, Packet*); // Construct from serialized buffer

  PendingData (const PendingData&);   // Copy constructor

  virtual ~PendingData ();     // Destructor

  uint32_t Size () const { return size;}

  // Serialization

  uint8_t*  Serialize (uint8_t*, uint32_t&); // Serialize to a buffer

  uint8_t*  Construct (uint8_t*, uint32_t&); // Construct from buffer

  virtual void Clear ();// Remove all associated data

  virtual void Add (uint32_t s, const uint8_t* d = 0);// Add some data to end

  virtual void Add (Ptr<Packet> p);

  /**

   * This method returns the number of bytes in the PendingData buffer

   * beyond the sequence number specified by seqOffset.

   *

   * The variables seqFront and seqOffset correspond to a sequence number

   * space in use by the user.  What is significant in this method is the

   * difference between them; i.e. the quantity (seqOffset - seqFront). 

   * This difference is subtracted from Size(), yielding the number of

   * bytes beyond seqOffset, from the user perspective, in the PendingData

   * buffer.

   *

   * If the first number specified is not a sequence number that corresponds

   * to the first data byte in the PendingData buffer, the computation

   * returned will be in error.

   * 

   * \return number of bytes 

   * \param seqFront sequence number of assumed first byte in the PendingData

   * \param seqOffset sequence number of offset 

   */

  virtual uint32_t SizeFromSeq (const SequenceNumber32& seqFront, const SequenceNumber32& seqOffset);

  // Inquire available data from offset

  /**

   * \return number of bytes in the data buffer beyond the offset specified

   * \param offset offset (from zero) 

   */

  virtual uint32_t SizeFromOffset (uint32_t offset);

  // Available size from sequence difference 

  /**

   * Subtracts seqFront from seqOffset after enforcing seqFront is less

   * than seqOffset

   *

   * \param seqFront sequence number to be subtracted from seqOffset

   * \param seqOffset higher sequence number

   * \return seqOffset-seqFront

   */

  virtual uint32_t OffsetFromSeq (const SequenceNumber32& seqFront, const SequenceNumber32& seqOffset);

  virtual Ptr<Packet> CopyFromOffset (uint32_t, uint32_t);  // Size, offset, ret packet

  // Copy data, size, offset specified by sequence difference

  virtual Ptr<Packet> CopyFromSeq (uint32_t, const SequenceNumber32&, const SequenceNumber32&);

  /**

   * Permits object to clear any pending data between seqFront and 

   * seqOffset - 1).  Callers should check the return value to determine

   * whether any data was removed from the front.

   *

   * \param seqFront sequence number to start to try to remove from 

   * \param seqOffset first sequence number in buffer that should be retained

   * \return number of bytes from the front that were removed from the buffer

   */

  virtual uint32_t RemoveToSeq (const SequenceNumber32& seqFront, const SequenceNumber32& seqOffset);

  PendingData*   Copy () const;          // Create a copy of this header

  PendingData*   CopyS (uint32_t);         // Copy with new size

  PendingData*   CopySD (uint32_t, uint8_t*); // Copy with new size, new data

public:

  uint32_t size;        // Number of data bytes

  std::vector<Ptr<Packet> > data;         // Corresponding data (may be null)

  // The next two fields allow simulated applications to exchange some info

  uint32_t msgSize;     // Total size of message

  uint32_t responseSize;// Size of response requested

};

}//namepsace ns3

#endif