/*--------------------------------------------------------------- 
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 * ________________________________________________________________
 * National Laboratory for Applied Network Research 
 * National Center for Supercomputing Applications 
 * University of Illinois at Urbana-Champaign 
 * http://www.ncsa.uiuc.edu
 * ________________________________________________________________ 
 *
 * Extractor.hpp
 * by Ajay Tirumala (tirumala@ncsa.uiuc.edu)
 * -------------------------------------------------------------------
 * Extract data from a file, used to measure the transfer rates
 * for various stream formats. 
 *
 * E.g. Use a gzipped file to measure the transfer rates for 
 * compressed data
 * Use an MPEG file to measure the transfer rates of 
 * Multimedia data formats
 * Use a plain BMP file to measure the transfer rates of 
 * Uncompressed data
 *
 * This is beneficial especially in measuring bandwidth across WAN
 * links where data compression takes place before data transmission 
 * ------------------------------------------------------------------- */

#ifndef _EXTRACTOR_H
#define _EXTRACTOR_H

#include <stdlib.h>
#include <stdio.h>

class Extractor {

public :

    /**
     * Constructor
     * @arg fileName   Name of the file 
     * @arg size       Block size for reading
     */
    Extractor(char *fileName, int size);

    /**
     * Constructor
     * @arg fp         File Pointer 
     * @arg size       Block size for reading
     */
    Extractor(FILE *fp, int size);


    /*
     * Fetches the next data block from 
     * the file
     * @arg block     Pointer to the data read
     * @return        Number of bytes read
     */
    int getNextDataBlock(char *block);


    /**
     * Function which determines whether
     * the file stream is still readable
     * @return true, if readable; false, if not
     */
    bool canRead();

    /**
     * This is used to reduce the read size
     * Used in UDP transfer to accomodate the
     * the header (timestamp)
     * @arg delta         Size to reduce
     */
    void reduceReadSize(int delta);

    /**
     * Destructor
     */
    ~Extractor(); 

private:

    /**
     * Block size for reading
     */
    int size;

    /**
     * File pointer
     */
    FILE *in;
};

#endif































