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CSE 461 Project I

The first part of this project requires that you implement a class that will be used to simulate a disk drive. The disk drive will have numberofblocks many blocks where each block has blocksize many bytes. The interface for the class Sdisk should include :

Class Sdisk
{
public :
Sdisk(string diskname, int numberofblocks, int blocksize);
int getblock(int blocknumber, string& buffer);
int putblock(int blocknumber, string buffer);
int getnumberofblocks(); // accessor function
int getblocksize(); // accessor function
private :
string diskname;        // file name of software-disk
int numberofblocks;     // number of blocks on disk
int blocksize;          // block size in bytes
};

An explanation of the member functions follows :

  • Sdisk(diskname, numberofblocks, blocksize)
    This constructor incorporates the creation of the disk with the “formatting” of the device. It accepts the integer values numberofblocks, blocksize, a string diskname and creates a Sdisk (software-disk). The Sdisk is a file of characters which we will manipulate as a raw hard disk drive. The function will check if the file diskname exists. If the file exists, it is opened and treated as a Sdisk with numberofblocks many blocks of size blocksize. If the file does not exist, the function will create a file called diskname which contains numberofblocks*blocksize many characters. This file is logically divided up into numberofblocks many blocks where each block has blocksize many characters. The text file will have the following structure :
    Bytes 0 – blocksize-1Block 0Bytes blocksize – 2*blocksize-1Block 1Bytes 2*blocksize – 3*blocksize-1Block 2……Bytes ?-?Block numberofblocks-1
  • getblock(blocknumber,buffer)
    retrieves block blocknumber from the disk and stores the data in the string buffer. It returns an error code of 1 if successful and 0 otherwise.
  • putblock(blocknumber,buffer)
    writes the string buffer to block blocknumber. It returns an error code of 1 if successful and 0 otherwise.

IMPLEMENTATION GUIDELINES : It is essential that your software satisfies the specifications. These will be the only functions (in your system) which physically access the Sdisk. NOTE that you must also write drivers to test and demonstrate your program.