Write a C Program to implement Indexed File Allocation method.

Write a C Program to implement Indexed File Allocation method.

Description of Indexed allocation: Indexed allocation supports both sequential and direct access files. The file indexes are not physically stored as a part of the file allocation table. Whenever the file size increases, we can easily add some more blocks to the index. In this strategy, the file allocation table contains a single entry for each file. The entry consisting of one index block, the index blocks having the pointers to the other blocks. No external fragmentation.

Algorithm for Indexed File Allocation:

Step 1: Start.

Step 2: Let n be the size of the buffer

Step 3: check if there are any producer

Step 4: if yes check whether the buffer is full

Step 5: If no the producer item is stored in the buffer

Step 6: If the buffer is full the producer has to wait

Step 7: Check there is any consumer.If yes check whether the buffer is empty

Step 8: If no the consumer consumes them from the buffer

Step 9: If the buffer is empty, the consumer has to wait.

Step 10: Repeat checking for the producer and consumer till required

Step 11: Terminate the process.

/* Program to simulate indexed file allocation strategy */

Program Code:

#include<stdio.h>

#include<conio.h>

#include<stdlib.h>

void main()

{

int f[50], index[50],i, n, st, len, j, c, k, ind,count=0;

clrscr();

for(i=0;i<50;i++)

f[i]=0;

x:printf("Enter the index block: ");

scanf("%d",&ind);

if(f[ind]!=1)

{

printf("Enter no of blocks needed and no of files for the index %d on the disk : \n", ind);

scanf("%d",&n);

}

else

{

printf("%d index is already allocated \n",ind);

goto x;

}

y: count=0;

for(i=0;i<n;i++)

{

scanf("%d", &index[i]);

if(f[index[i]]==0)

count++;

}

if(count==n)

{

for(j=0;j<n;j++)

f[index[j]]=1;

printf("Allocated\n");

printf("File Indexed\n");

for(k=0;k<n;k++)

printf("%d-------->%d : %d\n",ind,index[k],f[index[k]]);

}

else

{

printf("File in the index is already allocated \n");

printf("Enter another file indexed");

goto y;

}

printf("Do you want to enter more file(Yes - 1/No - 0)");

scanf("%d", &c);

if(c==1)

goto x;

else

exit(0);

getch();

}

Program Output:

Enter the index block: 5

Enter no of blocks needed and no of files for the index 5 on the disk :

4

1 2 3 4

Allocated

File Indexed

5-------->1 : 1

5-------->2 : 1

5-------->3 : 1

5-------->4 : 1

Do you want to enter more file(Yes - 1/No - 0)1

Enter the index block: 4

4 index is already allocated

Enter the index block: 6

Enter no of blocks needed and no of files for the index 6 on the disk :

2

7 8

A5llocated

File Indexed

6-------->7 : 1

6-------->8 : 1

Do you want to enter more file(Yes - 1/No - 0)0