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reader.hpp

/* $Id: reader.hpp,v 1.6 2006-11-05 04:42:43 ganzhorn Exp $
 * This file is part of lfhex.
 * Copyright (C) 2006 Salem Ganzhorn <eyekode@yahoo.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation version 2.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
#ifndef _READER_H_
#define _READER_H_

//
// Interface for Reader object.
//
// Reader object supports:
// open(const QString& filename ); -> open a file for reading
// bool is_open();                 -> see if file is open
// close();                        -> free resources for open file.
// int read( vector<uchar>& v, int maxSize ) -> fill v with maxSize data from
//                                              open file.
// off_t seek( off_t offset );     -> move file pointer to offset offset.
//

#include <sys/types.h>
#include <stdio.h>

#include <vector>
#include <string>
#include <iostream>

#include "local.h"

typedef vector<uchar> ReadBuffer;

#ifdef __GNUC__
ostream& operator<< (ostream&out,const ReadBuffer& buff);
#endif

class Reader {
 public:
  // default is only 50*4k = 200k memory image.
  Reader(const string& filename = "",off_t npages = 50, off_t pageSize = 4096);
  ~Reader();

  bool open(const string& filename);
  bool close();
  bool eof();
  bool is_open() const;
  
  size_t read( ReadBuffer& v, size_t numBytes );
  off_t  seek( off_t offset );
  off_t tell() const; // returns the current offset or -1 if !open
  off_t size() const;
  const char* lastError() const;
  const char* filename() const;

  uchar operator[] (off_t offset); // cannot be const because it does change
                                   // data by loading/swapping pages
  off_t findIndex( off_t start, const vector<uchar>& data,
               off_t stop );
  off_t rFindIndex( off_t start, const vector<uchar>& data,
                off_t stop );
 protected:
  bool dataIsAtOffset( const vector<uchar>& data, off_t pos );
  bool loadPage(off_t pageIdx);
  bool freePage(off_t pageIdx);
  off_t nFreePages() const;
  off_t& nFreePages();

 protected:
  string        _error;
  FILE*         _fptr;
  bool          _is_open;
  bool          _eof;
  string        _filename;
  off_t         _offset;         // current offset
  off_t         _size;           // file size from fstat
  off_t         _pageSize;       // number of bytes in a page
  off_t         _firstPage;      // first currently loaded page
  off_t         _lastPage;       // last currently loaded page
  off_t         _maxPages;       // maximum number of pages which could be currently loaded
  off_t         _freePages;     // number of free pages
  vector< uchar *> _data;
};

#endif

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