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

/* Copyright (C) 1995, Tektronix Inc. All Rights Reserved.
 *
 *   Usage Restrictions
 *
 * License is granted to copy, to use, and to make and to use derivative
 * works for research and evaluation purposes only.
 *
 *   Disclaimer of Warranty
 *
 * 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
 * purpose.  In no event shall the copyright-holder be liable for any 
 * 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.
 *
 * The Tektronix Inc. does not represent or warrant that the programs
 * furnished hereunder are free of infringement of any third-party
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*/

/* IPortFromFile is an InputPort that reads from a file */
#ifndef iportfromfile_h
#define iportfromfile_h

#include "InputPort.H"

// FIX -- CacheSize should be specified in the constructor call.
#define CacheSize 4096
#define CYCLE 1
#define NOCYCLE 2

class IPortFromFile : public InputPort
{
public:
  IPortFromFile (char*, int);
protected:
  virtual char input_bit ();
  virtual char input_byte ();  
private:
  int cycle_flag;
  char* file_name;
  int fd;
  char fbuf[CacheSize];
  int  flen;
  int  bufpos;
  char byte;
  int pos;
  int inc_bit ();
  char bit2char ();
};

/*
 DOCUMENTATION

 IPortFromFile is a subclass of InputPort.  It provides
 implementations for the two virtual funtions input_bit and input_byte
 and, except for constructors, its public interface is inherited from
 the base class.  The port can be used in a CYCLE or NOCYCLE modes.
 When in CYCLE mode the port will loop back to the beginning of the
 file when the EOF is encountered, thus providing a ongoing stream of
 bits.  When in NOCYCLE mode the port will call sys_halt when the EOF
 is reached.

 File reads are cached to improve performance.  The current cache size
 is set in the code to 4096.

 Public methods are:

  IPortFromFile (char*, int);
    The second (integer) parameter is the cycle flag (either CYCLE or
    NOCYCLE).
*/

#endif