delaychan.h

Go to the documentation of this file.

/*
 * delaychan.h
 *
 * Class for implementing a serial queue channel in memory.
 *
 * Portable Windows Library
 *
 * Copyright (c) 2001 Equivalence Pty. Ltd.
 *
 * 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.
 *
 * The Original Code is Portable Windows Library.
 *
 * The Initial Developer of the Original Code is Equivalence Pty. Ltd.
 *
 * Contributor(s): ______________________________________.
 *
 * $Log: delaychan.h,v $
 * Revision 1.10  2007/04/18 23:49:50  csoutheren
 * Add usage of precompiled headers
 *
 * Revision 1.9  2006/07/21 01:03:12  csoutheren
 * Fixed to PAdaptiveDelay
 * Thanks to Paolo Amadini
 *
 * Revision 1.8  2006/07/19 06:03:34  csoutheren
 * Add extension PAdaptiveDelay to set maximum and minimum delay times
 * Thanks to Paolo Amadini
 *
 * Revision 1.7  2006/06/20 12:44:02  csoutheren
 * Added new constructor for PDelayChannel
 * Thanks to Frederic Heem
 *
 * Revision 1.6  2005/11/30 12:47:37  csoutheren
 * Removed tabs, reformatted some code, and changed tags for Doxygen
 *
 * Revision 1.5  2004/11/11 07:34:50  csoutheren
 * Added #include <ptlib.h>
 *
 * Revision 1.4  2002/09/16 01:08:59  robertj
 * Added #define so can select if #pragma interface/implementation is used on
 *   platform basis (eg MacOS) rather than compiler, thanks Robert Monaghan.
 *
 * Revision 1.3  2002/02/25 11:05:02  rogerh
 * New Delay code which solves the accumulated error problem. Based on ideas
 * by Tomasz Motylewski <T.Motylewski@bfad.de>, Roger and Craig.
 *
 * Revision 1.2  2002/01/15 03:55:43  craigs
 * Added PAdaptiveDelay class
 *
 * Revision 1.1  2001/07/10 03:07:07  robertj
 * Added queue channel and delay channel classes to ptclib.
 *
 */

#ifndef _DELAYCHAN_H
#define _DELAYCHAN_H


#ifdef P_USE_PRAGMA
#pragma interface
#endif

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

class PAdaptiveDelay : public PObject
{ 
  PCLASSINFO(PAdaptiveDelay, PObject);
  
  public:

    PAdaptiveDelay(
      unsigned maximumSlip = 0,   
      unsigned minimumDelay = 0   
    );

    void SetMaximumSlip(PTimeInterval maximumSlip)
    { jitterLimit = maximumSlip; }

    PTimeInterval GetMaximumSlip() const
    { return jitterLimit; }

    BOOL Delay(int time);

    void Restart();
 
  protected:
    BOOL   firstTime;
    PTime  targetTime;

    PTimeInterval  jitterLimit;
    PTimeInterval  minimumDelay;
};


class PDelayChannel : public PIndirectChannel
{
    PCLASSINFO(PDelayChannel, PIndirectChannel);
  public:
    enum Mode {
      DelayReadsOnly,
      DelayWritesOnly,
      DelayReadsAndWrites
    };

    PDelayChannel(
      Mode mode,                  
      unsigned frameDelay,        
      PINDEX frameSize = 0,       
      unsigned maximumSlip = 250, 
      unsigned minimumDelay = 10  
    );
    
    PDelayChannel(
        PChannel &channel,          
        Mode mode,                  
        unsigned frameDelay,        
        PINDEX frameSize = 0,       
        unsigned maximumSlip = 250, 
        unsigned minimumDelay = 10  
                 );    


    virtual BOOL Read(
      void * buf,   
      PINDEX len    
    );

    virtual BOOL Write(
      const void * buf, 
      PINDEX len        
    );


  protected:
    virtual void Wait(PINDEX count, PTimeInterval & nextTick);

    Mode          mode;
    unsigned      frameDelay;
    PINDEX        frameSize;
    PTimeInterval maximumSlip;
    PTimeInterval minimumDelay;

    PTimeInterval nextReadTick;
    PTimeInterval nextWriteTick;
};


#endif // _DELAYCHAN_H


// End Of File ///////////////////////////////////////////////////////////////

---