indexed.c

//Program to implement Indexed File allocation
#include <stdio.h>
#define MAX 100

int blocks[MAX];
int indices[10];
typedef struct {
	int start;
	int len;
	int alloc[25];
	int flag;
}files;

files file[10];

void allocate(int fno) 
{
	int i = file[fno].start;
	int count = 0;

	do {
		if((i == file[fno].start) && (blocks[i] == 1))
		{
			file[fno].flag = 0;
			break;
		}

		if(blocks[i] == 0)
		{
			blocks[i] = 1;
			file[fno].alloc[count] = i;
			count++;
		}
		i = (i+1) % MAX;
	}while(i!=file[fno].start && count<file[fno].len);

	if(count == file[fno].len)
		file[fno].flag = 1;
	else
		file[fno].flag = 0;
}

void display(int n)
{
	int i,j;
	printf("\n-----------------------------\n");
	printf("The indices locations are: \n");
	printf("File No.\tIndex block\tStarting block\tLength\tStatus\n");
	for (int i = 0; i < n; i++)
	{
		if(indices[i] != -1 && file[i].flag == 1)
			printf("%d\t\t%d\t\t%d\t\t%d\tAllocated\n", (i+1), indices[i], file[i].start, file[i].len);
		else
			printf("%d\t\t-\t\t-\t\t-\tUnallocated\n", (i+1));
	}

	for (i = 0; i < n; i++)
	{
		if(file[i].flag == 1)
		{
			printf("\nIndex Block of File %d\n", (i+1));
			printf("\nBlock No.\tBlock Location\n");
			for(j=0; j < file[i].len; j++)
				printf("%d\t\t%d\n", (j+1), file[i].alloc[j]);
		}
	}
}

void main()
{
	int n, filled, x;
	for(int i=0;i<MAX;i++)
		blocks[i] = 0;

	printf("Enter the number of blocks already occupied: ");
	scanf("%d", &filled);
	for(int i=0; i<filled; i++)
	{
		printf("Enter the location of the occupied block: ");
		scanf("%d", &x);
		blocks[x] = 1;
	}

	printf("Enter the number of files to be allocated: ");
	scanf("%d", &n);
	for (int i = 0; i < n; i++)
	{
		printf("\nEnter the location of the Index block for File %d: ", (i+1));
		scanf("%d", &x);
		if(blocks[x] == 0)
		{
			blocks[x] = 1;
			indices[i] = x;
		}
		else
		{
			indices[i] = -1;
			printf("Index block is already occupied! Unable to store File %d\n", (i+1));
			continue;
		}
		printf("Enter the starting location of File %d: ", (i+1));
		scanf("%d", &file[i].start);
		printf("Enter the length of File %d: ", (i+1));
		scanf("%d", &file[i].len);
		allocate(i);
		if(file[i].flag == 1)
			printf("File %d was successfully allocated in the disk!\n", (i+1));
		else
			printf("Starting location is already occupied! Unable to allocate disk space to File %d\n", (i+1));
	}
	display(n);
}

linked.c

//Program to implement Linked File allocation
#include <stdio.h>
#define MAX 100

int blocks[MAX];
typedef struct {
	int start;
	int len;
	int alloc[25];
	int flag;
}files;

files file[10];

void allocate(int fno) 
{
	int i = file[fno].start;
	int count = 0;

	do {
		if((i == file[fno].start) && (blocks[i] == 1))
		{
			file[fno].flag = 0;
			break;
		}

		if(blocks[i] == 0)
		{
			blocks[i] = 1;
			file[fno].alloc[count] = i;
			count++;
		}
		i = (i+1) % MAX;
	}while(i!=file[fno].start && count<file[fno].len);

	if(count == file[fno].len)
		file[fno].flag = 1;
	else
		file[fno].flag = 0;
}

void display(int n)
{
	int i,j;
	printf("File No.\tStarting block\tLength\tStatus\t\tBlocks\n");
	for (i = 0; i < n; i++)
	{
		if(file[i].flag == 1)
		{
			printf("%d\t\t%d\t\t%d\tAllocated\t", (i+1), file[i].start, file[i].len);
			for(j=0; j < file[i].len-1; j++)
				printf("%d -> ", file[i].alloc[j]);
			printf("%d\n", file[i].alloc[j]);
		}
		else
		{
			printf("%d\t\t-\t\t-\tUnallocated\t\t-\n", (i+1));
		}
	}
}

void main()
{
	int n, filled, x;
	for(int i=0;i<MAX;i++)
		blocks[i] = 0;

	printf("Enter the number of blocks already occupied: ");
	scanf("%d", &filled);
	for(int i=0; i<filled; i++)
	{
		printf("Enter the location of the occupied block: ");
		scanf("%d", &x);
		blocks[x] = 1;
	}

	printf("Enter the number of files to be allocated: ");
	scanf("%d", &n);
	for (int i = 0; i < n; i++)
	{
		printf("\nEnter the starting location of File %d: ", (i+1));
		scanf("%d", &file[i].start);
		printf("Enter the length of File %d: ", (i+1));
		scanf("%d", &file[i].len);
		allocate(i);
		if(file[i].flag == 1)
			printf("File %d was successfully allocated in the disk!\n", (i+1));
		else
			printf("Unable to allocate disk space to File %d\n", (i+1));
	}
	display(n);
}

paging.c

// Program to implement paging in C
#include <stdio.h>
#include <stdlib.h>

typedef struct {
	int page_no;
	int frame_no;
} page_table;

int pages, page_size, mem_size;
page_table pg_tab[100];

void input() //To input the data regarding pages, memory size and the page table
{
	printf("Enter the size of the Physical memory(kB): ");
	scanf("%d", &mem_size);

	printf("Enter the size of one page(kB): ");
	scanf("%d", &page_size);

	int frames = mem_size/page_size;
	printf("\nNumber of available frames: %d", frames);

	printf("\nEnter the number of pages: ");
	scanf("%d", &pages);

	if(pages > frames)
	{
		printf("Number of pages cannot exceed the number of frames. Terminating...\n");
		exit(0);
	}

	printf("\nInput the page table. Enter frame no as -1 for unallocated pages.\n");
	printf("Page No.\tFrame No.\n");
	for (int i = 0; i < pages; ++i)
	{
		scanf("%d\t\t%d", &pg_tab[i].page_no, &pg_tab[i].frame_no);
	}
	printf("-------------------------\n");
}

void getPhysicalAddress() //To calculate the physical address
{
	int pg, offset, phy_add, log_add, flag=0;
	// printf("\nEnter the page number to be used for calculating the logical address: ");
	// scanf("%d", &pg);
	// printf("Enter the offset: ");
	// scanf("%d", &offset);

	printf("\nEnter the Logical Address: ");
	scanf("%d", &log_add);

	pg = log_add / page_size;
	offset = log_add % page_size;
	printf("Page No: %d\t\tOffset: %d", pg, offset);

	if(log_add > mem_size)
	{
		printf("\nLogical Address cannot exceed memory size. Terminating...\n");
		exit(0);
	}

	if(pg > pages)
	{
		printf("\nPage No cannot exceed total number of pages. Terminating...\n");
		exit(0);
	}

	for (int i = 0; i < pages; ++i)
	{
		if(pg_tab[i].page_no == pg)
		{
			if(pg_tab[i].frame_no == -1)
			{
				flag = 1;
				break;
			}
			else
			{
				phy_add = pg_tab[pg].frame_no*page_size + offset;	
				break;
			}
		}
	}

	if(flag == 0)
		printf("\nThe Physical Address corresponding to the given logical address is: %d\n", phy_add);
	else
		printf("\nThe page hasn't yet been allocated in memory yet.\n");
}

void main()
{
	input();
	getPhysicalAddress();
}

sequential.c

// Program to implement Sequential File allocation
#include <stdio.h>

int files[100], start[10], len[10], alloc[10];

void allocate(int fno) {
	int count = 0;
	for(int i=start[fno]; i < (start[fno] + len[fno]); i++) 
		if(files[i] == 0)
			count++;

	if(count == len[fno])
	{
		for(int i=start[fno]; i < (start[fno] + len[fno]); i++)
			files[i] = 1;

		alloc[fno] = 1;
	}
	else
		alloc[fno] = 0;
}

void display(int n) {
	printf("\nFile No.\tStarting block\tLength\tStatus\n");
	for(int i=0; i < n; i++)
	{
		if(alloc[i] == 1)
			printf("%d\t\t%d\t\t%d\tAllocated\n", (i+1), start[i], len[i]);
		else
			printf("%d\t\t-\t\t-\tUnallocated\n", (i+1));
	}
}

void main() {
	for(int i=0;i<100;i++)
		files[i] = 0;

	int n;
	printf("Enter the number of files: ");
	scanf("%d", &n);

	for(int i=0;i<n;i++)
	{
		printf("\nEnter the starting location of File %d: ", (i+1));
		scanf("%d", &start[i]);
		printf("Enter the length of File %d: ", (i+1));
		scanf("%d", &len[i]);
		allocate(i);
		if(alloc[i] == 1)
			printf("File %d was successfully allocated in the disk!\n", (i+1));
		else
			printf("Unable to allocate disk space to File %d\n", (i+1));
	}
	printf("\n-----------------------------\n");
	printf("The File allocation table is: \n");
	display(n);
}