delaychan.h

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/*
 * 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): ______________________________________.
 *
 * $Revision: 20385 $
 * $Author: rjongbloed $
 * $Date: 2008-06-04 10:40:38 +0000 (Wed, 04 Jun 2008) $
 */

#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; }

    PBoolean Delay(int time);

    void Restart();
 
  protected:
    PBoolean   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 PBoolean Read(
      void * buf,   
      PINDEX len    
    );

    virtual PBoolean 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


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