q922.h

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/*
 * q922.h
 *
 * Q.922 PDU implementation for the OpenH323 Project.
 *
 * Copyright (c) 2006 Network for Educational Technology, ETH Zurich.
 * Written by Hannes Friederich.
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * Contributor(s): ______________________________________.
 *
 * $Revision: 19279 $
 * $Author: rjongbloed $
 * $Date: 2008-01-17 04:08:34 +0000 (Thu, 17 Jan 2008) $
 */

#ifndef __OPAL_Q922_H
#define __OPAL_Q922_H

#ifdef P_USE_PRAGMA
#pragma interface
#endif

#ifndef _PTLIB_H
#include <ptlib.h>
#endif

#define Q922_HEADER_SIZE 3

class Q922_Frame : public PBYTEArray
{
  PCLASSINFO(Q922_Frame, PBYTEArray);
        
public:
        
  Q922_Frame(PINDEX informationFieldSize = 260);
  ~Q922_Frame();
        
  BYTE GetHighOrderAddressOctet() const { return theArray[0]; }
  BYTE GetLowOrderAddressOctet() const { return theArray[1]; }
  void SetHighOrderAddressOctet(BYTE octet) { theArray[0] = octet; }
  void SetLowOrderAddressOctet(BYTE octet) { theArray[1] = octet; }
        
  BYTE GetControlFieldOctet() const { return theArray[2]; }
  void SetControlFieldOctet(BYTE octet) { theArray[2] = octet; }
        
  BYTE *GetInformationFieldPtr() const { return (BYTE *)(theArray + Q922_HEADER_SIZE); }
        
  PINDEX GetInformationFieldSize() const { return informationFieldSize; }
  void SetInformationFieldSize(PINDEX size);
        
  PBoolean Decode(const BYTE *data, PINDEX size);
        
  PINDEX GetEncodedSize() const;
  
  PBoolean Encode(BYTE *buffer, PINDEX & size) const;

  PBoolean Encode(BYTE *buffer, PINDEX & size, BYTE & bitPosition) const;
        
protected:
        
  PINDEX informationFieldSize;
        
private:

  inline PBoolean FindFlagEnd(const BYTE *buffer, PINDEX bufferSize, PINDEX & octetIndex, BYTE & bitIndex);
  inline BYTE DecodeByte(const BYTE *buffer, BYTE *destination, PINDEX & octetIndex, BYTE & bitIndex, BYTE & onesCounter);
  inline BYTE DecodeBit(const BYTE *buffer, PINDEX & octetIndex, BYTE & bitIndex);
        
  inline void EncodeOctet(BYTE octet, BYTE *buffer, PINDEX & octetIndex, BYTE & bitIndex, BYTE & onesCounter) const;
  inline void EncodeOctetNoEscape(BYTE octet, BYTE *buffer, PINDEX & octetIndex, BYTE & bitIndex) const;
  inline void EncodeBit(BYTE bit, BYTE *buffer, PINDEX & octetIndex, BYTE & bitIndex) const;
        
  inline WORD CalculateFCS(const BYTE*data, PINDEX length) const;
};

#endif // __OPAL_Q922_H

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