www.pudn.com > MPEG2systemsrc.rar > SectionProducers.H

/* Copyright (C) 1995, Tektronix Inc. All Rights Reserved.
 *
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 * works for research and evaluation purposes only.
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 * These software programs are available to the user without any license
 * fee or royalty on an "as is" basis.  Tektronix Inc. disclaims any and
 * all warranties, whether express, implied, or statuary, including any
 * implied warranties or merchantability or of fitness for a particular
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 * incidental, punitive, or consequential damages of any kind whatsoever
 * arising from the use of these programs.
 *
 * This disclaimer of warranty extends to the user of these programs and
 * user's customers, employees, agents, transferees, successors, and
 * assigns.
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 * The Tektronix Inc. does not represent or warrant that the programs
 * furnished hereunder are free of infringement of any third-party
 * patents.
*/

/* SectionProducer classes */
#ifndef secproducer_h
#define secproducer_h

#include "Producer.H"
#include "Section.H"
#include "Directory.H"
#include "Encoder.H"

class SectionProducer : public Producer
{
public:
  SectionProducer (Encoder*, Section*);
protected:
  virtual int fill_buffer ();
  virtual void send_section () = 0;
  void send_header_a ();            // table_id .. section_length
  void send_header_b ();            // reserved .. last_section_number
  void send_CRC ();
private:
  Section* sec;
};

class PATProducer : public SectionProducer
{
public:
  PATProducer (Encoder*, PATSection*);
  virtual void send_section ();
  PATSection* patsec;
};

class MapProducer : public SectionProducer
{
public:
  MapProducer (Encoder*, MapSection*);
  virtual void send_section ();
  MapSection* mapsec;
private:
};

class CAProducer : public SectionProducer
{
public:
  CAProducer (Encoder*, CASection*);
  virtual void send_section ();
private:
  CASection* casec;
};

/*
 DOCUMENTATION

 SectionProducer is a base class from which the PSI-related Producers
 PATProducer, MapProducer and CAProducer are derived.

 Since the syntax for these sections is similar reproduction of code
 is avoided by defining fill_buffer in the base class SectionProducer
 and calling the virtual function send_section.  send_section is
 defined in each of the derived classes.  The definitions of
 send_section, then, use as utilities the functions send_header_a and
 send_header_b, which are defined back in the base class. 

 Note that the syntax objects: casec, mapsec and patsec are stored
 twice in each structure.  Once under the generic name "sec" and once
 under the more specific name.  This is a hack to work around a
 well-known and annoying C++ strong-typing problem; if you don't mind
 the extra pointer and they are "write-once", then it's a pretty
 effective solution.

*/

#endif