System Software /Operating System Lab Report

System Software Lab

Vishnu K N
S5 CSE B 59

1.FCFS Scheduling

#include<stdio.h>
#include<string.h>

struct process
{
char name[20];
int at,bt,wt,tt,status;
}p[20],temp;

struct gantt
{
int st,ct;
char name[20];
}d[20];

void main()
{
int n=0,s=0,sum=0,num,i,j,k,idle;
ﬂoat avg_wt=0,avg_tt=0;
char c[20];
printf("Enter the number of processes");
scanf("%d",&n);
for(i=0;i<n;i++)
{
printf("Enter the name of the process :");
scanf("%s",p[i].name);
__fpurge(stdin);
printf("Enter the arrival time of process %d :",i+1);
scanf("%d",&p[i].at);
printf("Enter the burst time of process %d :",i+1);
scanf("%d",&p[i].bt);
p[i].status=0;
}
for(i=0;i<n;i++)
{
for(j=0;j<(n-i-1);j++)
{
if(p[j].at>p[j+1].at)
{
temp=p[j];
p[j]=p[j+1];

p[j+1]=temp;
}
}
}
idle=0;
for(i=0,k=0,num=0;k<n;)
{
if((p[k].at<=i)&&p[k].status==0)
{
//idle=1;
if(idle==1)
{
d[num].ct=i;
num++;
}
strcpy(d[num].name,p[k].name);
d[num].st=i;
printf("%d",d[num].st);
d[num].ct=d[num].st+p[k].bt; //completion time
printf("%dn",d[num].ct);
p[k].wt=d[num].st-p[k].at; //waiting time
p[k].tt=p[k].wt+p[k].bt; //waiting time
i=d[num].ct;
p[k].status=1;
k++;
num++;
idle=0;
}
else if(idle==0)
{
//printf("HEREn");
strcpy(d[num].name,"idle");
d[num].st=i;
idle=1;i++;
}
else
{
i++;
}

}

printf("Process AT BT CT WT TTn");
for(i=0;i<n;i++)
{
printf("%s %3d %3d %3d %3d
%3dn",p[i].name,p[i].at,p[i].bt,d[i+1].ct,p[i].wt,p[i].tt);
}

for(i=0;i<num;i++)
{
printf("_________");
}
printf("n|");
for(i=0;i<num;i++)
{
printf("%s |",d[i].name);
}
printf("n");
for(i=0;i<num;i++)
{
printf("---------");
}
printf("n");
for(i=0;i<num;i++)
{
printf("%d ",d[i].st);
}
printf("%dn",d[i-1].ct);

printf("The average waiting time :");
for(i=0;i<n;i++)
{
avg_wt=avg_wt+p[i].wt;
}
avg_wt=avg_wt/n;
printf("%f",avg_wt);
printf("nThe average turn around time is :");
for(i=0;i<n;i++)
{
avg_tt=avg_tt+p[i].tt;
}
avg_tt=avg_tt/n;
printf("%f",avg_tt);

}

Output
Enter the number of processes:2
Enter the name of the process :a
Enter the arrival time of process 1 :0
Enter the burst time of process 1 :2
Enter the name of the process :b

Process AT BT CT WT TT
a 0 2 6 0 2
b 2 4 0 0 4
___________
|a |b |
------------------
0 2 6
The average waiting time :0.000000
The average turnaround time is :3.000000

2.SJF Scheduling

#include<stdio.h>
#include<string.h>

struct process
{
char name[20];
int at,bt,wt,tt,status;
}p[20],temp;

struct gantt
{
int st,ct;
char name[20];
}d[20];

void main()
{
int n=0,s=0,sum=0,num,i,j,k=0,idle,ﬂag,found,ls;
char c[20];
scanf("%d",&n);
for(i=0;i<n;i++)
{
__fpurge(stdin);
p[i].status=0;
}
for(i=0;i<n;i++)
{
for(j=0;j<(n-i-1);j++)
{
{
temp=p[j];
p[j]=p[j+1];

p[j+1]=temp;
}
}
}

for(i=0;i<n;i++)
{
printf("%sn",p[i].name);}
ls=0;idle=0;
for(i=0;ls<n;)
{
flag=0,found=0;
for(j=0;j<n;j++)
{
if(p[j].status==0&&p[j].at<=i&&found==0)
{
k=j;flag++;found++;
}
else if(p[j].status==0&&p[j].at<=i&&found>0)
{
if(p[j].bt<p[k].bt)
k=j;
}
}
if(flag==0&&idle==0)
{
d[num].st=i;
idle=1;i++;
}
else if(flag>0)
{
if(idle==1)
{
d[num].ct=i;
num++;
}
d[num].st=i;
d[num].ct=i+p[k].bt;
p[k].wt=d[num].st-p[k].at;
p[k].tt=p[k].wt+p[k].bt;
i=d[num].ct;

num++;
p[k].status=1;
idle=0;
ls++;k++;
found++;
}
else
{
i++;
}

}

for(i=0;i<n;i++)
{
printf("%s %d %d %d %d %dn",p[i].name,p[i].at,p[i].bt,d[i+1].ct,p[i].wt,p[i].tt);
}
for(i=0;i<num;i++)
{
printf("___________");
}
printf("n|");
for(i=0;i<num;i++)
{
printf("%4s |",d[i].name);
}
printf("n");
for(i=0;i<num;i++)
{
printf("-----------");
}
printf("n");
for(i=0;i<num;i++)
{
}

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

}
avg_wt=avg_wt/n;
for(i=0;i<n;i++)
{
}
avg_tt=avg_tt/n;
printf("%fn",avg_tt);

}

Output


a 0 3 5 2 5
b 0 2 0 0 2
_____________
| b | a |
----------------------
0 2 5

3.Priority Scheduling

#include<stdio.h>
#include<string.h>

struct process
{
char name[20];
int at,bt,wt,tt,status,priority;
}p[20],temp;

struct gantt
{
int st,ct;
char name[20];
}d[20];

void main()
{
char c[20];
scanf("%d",&n);
for(i=0;i<n;i++)
{
__fpurge(stdin);
printf("Enter the priority of process %d :",i+1);
scanf("%d",&p[i].priority);
p[i].status=0;
}
for(i=0;i<n;i++)
{
for(j=0;j<(n-i-1);j++)
{
{

temp=p[j];
p[j]=p[j+1];
p[j+1]=temp;
}
}
}

for(i=0;i<n;i++)
{
printf("%sn",p[i].name);}
ls=0;idle=0;
for(i=0;ls<n;)
{
flag=0,found=0;
for(j=0;j<n;j++)
{
if(p[j].status==0&&p[j].at<=i&&found==0)
{
k=j;flag++;found++;
}
else if(p[j].status==0&&p[j].at<=i&&found>0)
{
if(p[j].priority<p[k].priority)
k=j;
}
}
if(flag==0&&idle==0)
{
d[num].st=i;
idle=1;i++;
}
else if(flag>0)
{
if(idle==1)
{
d[num].ct=i;
num++;
}
d[num].st=i;
d[num].ct=i+p[k].bt;
p[k].wt=d[num].st-p[k].at;

p[k].tt=p[k].wt+p[k].bt;
i=d[num].ct;
num++;
p[k].status=1;
idle=0;
ls++;k++;
found++;
}
else
{
i++;
}

}

printf("Process AT BT PT CT WT TTn");
for(i=0;i<n;i++)
{
printf("%s %d %d %d %d %d
%dn",p[i].name,p[i].at,p[i].bt,p[i].priority,d[i+1].ct,p[i].wt,p[i].tt);
}
for(i=0;i<num;i++)
{
printf("___________");
}
printf("n|");
for(i=0;i<num;i++)
{
}
printf("n");
for(i=0;i<num;i++)
{
printf("-----------");
}
printf("n");
for(i=0;i<num;i++)
{
}

for(i=0;i<n;i++)
{
}
avg_wt=avg_wt/n;
for(i=0;i<n;i++)
{
}
avg_tt=avg_tt/n;

}

Output

Enter the priority of process 1 :1
Enter the name of the process :c
Enter the name of the process :d

Process AT BT PT CT WT TT
a 0 4 1 9 0 4
b 0 5 2 12 4 9
c 1 3 2 20 8 11
d 20 4 3 24 0 4

_________________________________
| a | b | c |idle | d |
-------------------------------------------------------
0 4 9 12 20 24

4.Round Robin Scheduling

#include<stdio.h>
#include<string.h>

struct process
{
char name[20];
int at,bt,wt,tt,status,left;
}p[20],temp;

struct gantt
{
int st,ct;
char name[20];
}d[20];
int front=-1,rear=0;

void main()
{
int t=0;
int left=0,q[30];
void enqueue(int j)
{
q[rear]=j;
rear++;
if(front==-1)
{
front++;
}
}
int dequeue()
{
int item;
item=q[front];
front++;
if(front==rear)
{
front=-1;
rear=0;
}
return item;
}

printf("Enter the value for time quantum :n");
scanf("%d",&t);
char c[20];
scanf("%d",&n);
for(i=0;i<n;i++)
{
__fpurge(stdin);
p[i].status=0;
p[i].left=p[i].bt;
}
ls=0;
idle=0;
for(i=0;ls<n;)
{
for(j=0;j<n;j++)
{
if(p[j].status==0&&p[j].at<=i)
{
enqueue(j);
p[j].status=1;
}
}
if(idle==0&&front==-1)
{
d[num].st=i;
idle=1;
i++;
}
else if(front!=-1)
{
if(idle==1)
{
d[num].ct=i;

idle=0;
num++;
}
k=dequeue();
d[num].st=i;
if(p[k].left<=t)
{
d[num].ct=i+p[k].left;
i=d[num].ct;
p[k].tt=i-p[k].at;
p[k].wt=p[k].tt-p[k].bt;
p[k].status=1;
ls++;
num++;
}
else
{
d[num].ct=i+t;
i=i+t;
p[k].left=p[k].left-t;
num++;
for(j=0;j<n;j++)
{
if(p[j].status==0&&p[j].at<=i)
{
enqueue(j);
p[j].status=1;
}

}
enqueue(k);
}
}
else
{
i++;
}
}

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

printf("%s %d %d %d %d %dn",p[i].name,p[i].at,p[i].bt,d[i+1].ct,p[i].wt,p[i].tt);
}
for(i=0;i<num;i++)
{
printf("___________");
}
printf("n|");
for(i=0;i<num;i++)
{
}
printf("n");
for(i=0;i<num;i++)
{
printf("-----------");
}
printf("n");
for(i=0;i<num;i++)
{
}

for(i=0;i<n;i++)
{
}
avg_wt=avg_wt/n;
for(i=0;i<n;i++)
{
}
avg_tt=avg_tt/n;

}

Output

Enter the value for time quantum :
2
Enter the name of the process :p0
p0 0 4 4 2 6
p1 2 3 6 4 7
p2 3 5 8 4 9
p3 20 3 9 0 3
_________________________________________________________________
| p0 | p1 | p0 | p2 | p1 | p2 | p2 |idle | p3 | p3 |
--------------------------------------------------------------------------------------------------------------
0 2 4 6 8 9 11 12 20 22 23

5.Producer Consumer

#include<stdio.h>
#include<pthread.h>
#include<semaphore.h>
#include<time.h>

sem_t mutex,empty,full;
int buffer[5],get=0,item=0,gitem,pro[20],con[20],put=0;

void *producer(void *args)
{

do
{
sem_wait(&empty);
sem_wait(&mutex);
buffer[put%5]=item;
item++;
printf("nProducer %d produces %d item buffered %d :%d",*(int *)
args,buffer[put%5],put%5,item);
put++;
sem_post(&mutex);
sem_post(&full);
sleep(1);
}while(1);
}
void *consumer(void *args)
{
do
{
sem_wait(&full);
sem_wait(&mutex);
gitem=buffer[get%5];
printf("nConsumer %d consumes %d item buffered %d :%d", *(int
*) args,buffer[get%5],get%5,gitem);
get ++;
sem_post(&mutex);
sem_post(&empty);
sleep(1);
}while(1);
}

void main()
{
int p,c,j,k;
pthread_t a[10],b[10];
sem_init(&mutex,0,1);
sem_init(&full,0,0);
sem_init(&empty,0,5);
printf("Enter the number of consumers");
scanf("%d",&c);
printf("Enter the number of producers");
scanf("%d",&p);
for(j=0;j<p;j++)
{
pro[j]=j;
pthread_create(&a[j],NULL,&producer,&pro[j]);
}
for(k=0;k<c;k++)
{
con[k]=k;
pthread_create(&b[k],NULL,&consumer,&con[k]);
}
for(j=0;j<p;p++)
{
pthread_join(a[j],NULL);
}
for(k=0;k<c;k++)
{
pthread_join(b[k],NULL);
}

}

Output

Enter the number of consumers:2
Enter the number of producers:2

Producer 0 produces 0 item buffered 0 :1
Consumer 0 consumes 0 item buffered 0 :0
Consumer 1 consumes 1 item buffered 1 :1

6.Dining Philosopher’s

#include<stdio.h>
#include<semaphore.h>
#include<pthread.h>
#include<time.h>

#define N 5
#define THINKING 0
#define HUNGRY 1
#define EATING 2
#define LEFT ((ph_num+4)%N)
#define RIGHT ((ph_num+1)%N)

sem_t mutex, s[N];

void *philosopher(void *num);
void take_fork(int);
void put_fork(int);
void test(int);
int state[N];
int ph_num[N]={0,1,2,3,4};

void main()
{
int i;
pthread_t thread_id[N];
sem_init(&mutex,0,1);
for(i=0;i<N;i++)
{
sem_init(&s[i],0,0);
}

for(i=0;i<N;i++)
{
pthread_create(&thread_id[i],NULL,&philosopher,&ph_num[i]);
printf("philosopher %d is thinking n",i+1);
}

for(i=0;i<N;i++)
{
pthread_join(thread_id[i],NULL);

}

}

void *philosopher(void *num)
{

while(1){
int *i=num;
sleep(1);
take_fork(*i);
sleep(0);
put_fork(*i);
}
}

void take_fork(int ph_num)
{
sem_wait(&mutex);
state[ph_num]=HUNGRY;
printf("philosopher %d is hungry n",ph_num+1);
test(ph_num);
sem_post(&mutex);
sem_wait(&s[ph_num]);
sleep(1);
}

void test(int ph_num)
{

if(state[ph_num]==HUNGRY && state[LEFT]!=EATING && state[RIGHT]!=EATING)
{
state[ph_num]=EATING;
sleep(2);
printf("philosopher %d takes fork %d and %d n",ph_num+1,LEFT+1,ph_num+1);
printf("philosopher %d is eating n",ph_num+1);
sem_post(&s[ph_num]);
}
}

void put_fork(int ph_num)
{
sem_wait(&mutex);

state[ph_num]=THINKING;
printf("philosopher %d putting fork %d and %d down n",ph_num+1,LEFT+1,ph_num+1);
printf("philosopher %d is thinking n",ph_num+1);
test(LEFT);
test(RIGHT);
sem_post(&mutex);
}

Output

philosopher 1 is thinking
philosopher 2 is hungry
philosopher 2 takes fork 1 and 2
philosopher 2 is eating
philosopher 2 putting fork 1 and 2 down

7.Banker’s Algorithm

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

void request(int Alloc[10][10],int Need[10][10],int Avail[10][10],int pid,int m)
{
int req[1][10];
int i;
printf("n Enter request to be executed :- n");
for(i=0;i<m;i++){
printf(" Request for resource %d : ",i+1);
scanf("%d",&req[0][i]);
}

for(i=0;i<m;i++){
if(req[0][i] > Need[pid][i]){
printf("n not possiblen");
exit(0);
}
}

for(i=0;i<m;i++){
if(req[0][i] > Avail[0][i]){
printf("n not possiblen");
exit(0);
}
}
for(i=0;i<m;i++){
Avail[0][i]-=req[0][i];
Alloc[pid][i]+=req[0][i];
Need[pid][i]-=req[0][i];
}
}

void print(int x[][10],int n,int m){
int i,j;
for(i=0;i<n;i++){
printf("n");
for(j=0;j<m;j++){
printf("%dt",x[i][j]);
}

}
}

void input(int Alloc[][10],int Need[][10],int Max[10][10],int Work[1][10],int *n,int *m){
int i,j;
printf("n Enter total no. of processes : ");
scanf("%d",n);
printf("n Enter total no. of resources : ");
scanf("%d",m);
for(i=0;i<*n;i++){
printf("n Process %dn",i+1);
for(j=0;j<*m;j++){
printf(" Allocation for resource %d : ",j+1);
scanf("%d",&Alloc[i][j]);
printf(" Maximum for resource %d : ",j+1);
scanf("%d",&Max[i][j]);
}
}
printf("n Available resources : n");
for(i=0;i<*m;i++){
printf(" Resource %d : ",i+1);
scanf("%d",&Work[0][i]);
}

for(i=0;i<*n;i++)
for(j=0;j<*m;j++)
Need[i][j]=Max[i][j]-Alloc[i][j];

printf("n Allocation Table ");
print(Alloc,*n,*m);
printf("n Maximum Table");
print(Max,*n,*m);
printf("n Need Table");
print(Need,*n,*m);

}

int safety(int Alloc[][10],int Need[][10],int Avail[1][10],int n,int m,int a[]){

int i,j,k,x=0;
int F[10],Work[1][10];
int pﬂag=0,ﬂag=0;

for(i=0;i<n;i++)
F[i]=0;
for(i=0;i<m;i++)
Work[0][i]=Avail[0][i];

for(k=0;k<n;k++){
for(i=0;i<n;i++){
if(F[i] == 0){
flag=0;
for(j=0;j<m;j++){
if(Need[i][j] > Work[0][j])
flag=1;
}
if(flag == 0 && F[i] == 0){
for(j=0;j<m;j++)
Work[0][j]+=Alloc[i][j];
F[i]=1;
pflag++;
a[x++]=i;
}
}
}
if(pflag == n)
return 1;
}
return 0;
}
int banker(int Alloc[][10],int Need[][10],int Work[1][10],int n,int m){
int j,i,a[10];
j=safety(Alloc,Need,Work,n,m,a);
if(j != 0 ){
printf("nn");
for(i=0;i<n;i++)
printf(" P%d ",a[i]);
printf("n Safe Sequence has been found.n");
return 1;
}else{
printf("n Not Permittedn");
return 0;
}
}

int main(){
int r;
int Alloc[10][10];
int Max[10][10];
int Need[10][10];
int Work[1][10];
int n,m,pid,ch;
input(Alloc,Need,Max,Work,&n,&m);
r=banker(Alloc,Need,Work,n,m);
if(r !=0 ){
printf("Press 0 to request:n");
scanf("%d",&ch);
if(ch==0)
{
printf("n Enter requesting process's' no : ");
scanf("%d",&pid);
request(Alloc,Need,Work,pid,m);
r=banker(Alloc,Need,Work,n,m);
if(r == 0 )
exit(0);
}
}
else
exit(0);
return 0;
}

Output

Enter total no. of processes : 5

Enter total no. of resources : 3

Process 1
Allocation for resource 1 : 0
Maximum for resource 1 : 7

Process 2

Process 3

Process 4

Process 5

Available resources :
Resource 1 : 3
Resource 2 : 3
Resource 3 : 2

Allocation Table
0 1 0
2 0 0
3 0 2
1 1 1
0 0 2
Maximum Table
7 5 3
3 2 2
9 0 2
2 1 2
4 3 3
Need Table
7 4 3
1 2 2
6 0 0
1 0 1
4 3 1

P1 P3 P4 P2 P0
Safe Sequence has been found.
Press 0 to request:
0

Enter requesting process's' no : 1

Enter request to be executed :-
Request for resource 1 : 1

P1 P3 P4 P2 P0
Safe Sequence has been found.

8. Fifo Page Replacement
#include<stdio.h>
void main()
{
int frame[10], i, j,n, a[50], f, k, avail;
int count=j=0;
printf("Enter the no. of pages:");
scanf("%d" ,&n);
printf("Enter the no. of frames:");
scanf("%d" ,&f);
printf("Enter the reference string:");
for(i=0;i<n;i++)
scanf("%d", &a[i]);
for(i=0;i<f;i++)
frame[i]=-1;
for(i=0;i<n;i++)
{
avail=0;
for(k=0; k<f;k++)
if(frame[k]==a[i])
avail=1;
if (avail==0)
{
frame[j]=a[i];
j=(j+1)%f;
count++;
}
for(k=0; k<f; k++)
printf("%dt", frame[k]);
}
printf("nPage Fault:%dn", count);
}
Output
Enter the no. of pages: 7
Enter the no. of frames: 3
Enter the reference string: 6 4 8 2 4 7 6
6 -1 -1
6 4 -1
6 4 8
2 4 8
2 4 8
2 7 8
2 7 6 Page Fault: 6

9. Lru Page Replacement

#include<stdio.h>
int findLRU(int time[], int n)
{
int min, pos,i;
min=time[0];
pos=0;
for (i=1;i<n;i++)
if (time[i]<min)
{
min=time[i];
pos=i;
}
return pos;
}
void main()
{
int f, n,i,k,j,pos, frames[10], pages[30], count=0, time[10],flag1,flag2, faults=0;
printf("Enter no. of pages:");
scanf("%d" ,&n);
printf("Enter the no. of frames:");
scanf("%d" ,&f);
printf("Enter the reference string:");
for(i=0;i<n;i++)
scanf("%d", &pages[i]);
for(i=0;i<f;i++)
frames[i]=-1;
for(i=0;i<n;i++)
{
flag1=flag2=0;
for(j=0; j<f;j++)
if(frames[j]==pages[i])
{
count++;
time[j]=count;
flag1=flag2=1;
break;
}
if (flag1==0)
{
for(j=0;j<f;j++)
{if (frames[j]==-1)

{
count++;
faults++;
frames[j]=pages[i];
time[j]=count;
flag2=1;
break;
}
}
}
if (flag2==0)
{
pos=findLRU(time,f);
count++;
faults++;
frames[pos]=pages[i];
time[pos]=count;
}
for(k=0; k<f; k++)
printf("%dt", frames[k]);
printf("n");
}
printf("Page Fault:%dn", faults);
}
Output
Enter no. of pages: 8
Enter the no. of frames: 3
Enter the reference string: 5 7 8 3 7 3 9 4
5 -1 -1
5 7 -1
5 7 8
3 7 8
3 7 8
3 7 8
3 7 9
3 4 9
Page Fault: 6

10. Disk Scheduling

#include<stdio.h>
void main()
{
printf("MENU n1.FCFSn2.SCANn3.CSCAN");
int ch;
char c;
do
{ printf("nEnter your choice:");
scanf("%d", &ch);
switch(ch)
{
case 1: fcfs();
break;
case 2: scan();
break;
case 3: cscan();
break;
default: printf("Wrong Choicen");
}
printf("nDo you want another implementation?(y/n):");
__fpurge(stdin);
scanf("%c", &c);
}while (c=='y');
}
void fcfs()
{
int q[50],n, head,i,j,k, seek=0,diff;
printf("Enter size of queue:");
scanf("%d",&n);
printf("Enter the queue:");
for(i=1;i<=n;i++)
scanf("%d",&q[i]);
printf("Enter head position:");
scanf("%d",&head);
q[0]=head;
printf("Seek Movement:n");
for (j=0;j<n;j++)
{
diff=abs(q[j+1]-q[j]);
seek+=diff;
printf("%d--->", q[j]);

}printf("%d", q[j]);
printf("n Total Head Movements:%dn", seek);
}
void scan()
{
int i,j,sum=0, n, d[20], head, temp, max,loc,diff1,diff2,diff,temp1[20],k=0;
scanf("%d", &n);
for(i=0;i<n;i++)
scanf("%d",&d[i]);
scanf("%d",&head);
d[n]=head;
n++;
for (i=0;i<n-1;i++)
{
for(j=0;j<n-i-1;j++)
{
if(d[j]>d[j+1])
{
temp=d[j];
d[j]=d[j+1];
d[j+1]=temp;
}
}
}
max=199;
for(i=0;i<n;i++)
{
if (head==d[i])
{
loc=i;
break;
}
}
diff1=head;
diff2=max-head;
if (diff1<diff2)
{
for(i=loc;i>=0;i--)
{
printf("%d--->",d[i]);

temp1[k]=d[i];
k++;
}
printf("0--->");
temp1[k]=0;
k++;
for(i=loc+1; i<n-1;i++)
{
temp1[k]=d[i];
k++;
}printf("%d",d[i]);
temp1[k]=d[i];
k++;
}
else
{
for(i=loc; i<n;i++)
{
temp1[k]=d[i];
k++;
}
printf("%d--->", max);
temp1[k]=max;
k++;
for(i=loc-1;i>0;i--)
{
temp1[k]=d[i];
k++;
}
printf("%dn",d[i]);
temp1[k]=d[i];
k++;
}
for(i=0;i<k-1;i++)
{
diff=abs(temp1[i]-temp1[i+1]);
sum+=diff;
}
printf("nHead Movements:%dn", sum);
}

void cscan()
{
int i,j,sum=0, n, d[20], head, temp, max,loc,diff1,diff2,diff,temp1[20],k=0;
scanf("%d", &n);
for(i=0;i<n;i++)
scanf("%d",&d[i]);
scanf("%d",&head);
d[n]=head;
n++;
for (i=0;i<n-1;i++)
{
for(j=0;j<n-i-1;j++)
{
if(d[j]>d[j+1])
{
temp=d[j];
d[j]=d[j+1];
d[j+1]=temp;
}
}}
max=199;
for(i=0;i<n;i++)
{
if (head==d[i])
{
loc=i;
break;
}
}
diff1=head;
diff2=max-head;
if (diff1<diff2)
{
for(i=loc;i>=0;i--)
{
temp1[k]=d[i];
k++;
}
printf("0--->");

temp1[k]=0;
k++;
printf("%d--->",max);
temp1[k]=max;
k++;
for(i=n-1; i>loc+1;i--)
{
temp1[k]=d[i];
k++;
}
printf("%d",d[i]);
temp1[k]=d[i];
k++;
}
else
{
for(i=loc; i<n;i++)
{
temp1[k]=d[i];
k++;
}
printf("%d--->", max);
temp1[k]=max;
k++;
printf("0--->");
temp1[k]=0;
k++;
for(i=loc-1;i>0;i--)
{
temp1[k]=d[i];
k++;
}
printf("%dn",d[i]);
temp1[k]=d[i];
k++;}
for(i=0;i<k-1;i++)
{
diff=abs(temp1[i]-temp1[i+1]);
sum+=diff;
}

printf("nHead Movements:%dn", sum);
}
Output
MENU
1. FCFS
2. SCAN
3. CSCAN
Enter your choice: 1
Enter size of queue: 6
Enter the queue: 53 45 78 87 34 56
Enter head position: 40
Seek Movement:
40--->53--->45--->78--->87--->34--->56
Total Head Movements: 138
Do you want another implementation? (y/n): y
MENU
1. FCFS
2. SCAN
3. CSCAN
Enter the queue: 56 78 90 45 79
55--->45--->0--->56--->78--->79--->90
Head Movements: 145
Do you want another implementation? (y/n): y
MENU
1. FCFS
2. SCAN
3. CSCAN
Enter the queue: 56 89 98 50 90 34
55--->50--->34--->0--->199--->98--->90--->89--->56
Head Movements: 397
Do you want another implementation? (y/n): n

11. Single Level Directory

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
struct
{
char dname[10], fname[10][10];
int fcnt;
} dir;
void main()
{
int i,ch,flag;
char f[30];
dir.fcnt=0;
printf("Enter the name of the Directory:");
scanf("%s", &dir.dname);
while(1)
{
flag=0;
printf("nMENU n1.Create Filen2.Delete Filen3.Search Filen4.Displayn5.Exitn");
printf("nEnter your choice:");
scanf("%d", &ch);
switch (ch)
{
case 1:printf("Enter name of the file:");
scanf("%s", &dir.fname[dir.fcnt]);
dir.fcnt++;
printf("File Createdn");
break;
case 2: printf("Enter name of the file to be deleted:");
scanf("%s", &f);
for(i=0;i<dir.fcnt;i++)
{
if (strcmp(f,dir.fname[i])==0)
{
printf("File Deleted!n");
strcpy(dir.fname[i], dir.fname[dir.fcnt-1]);
flag=1;
}
}
if (flag==0)
printf("File Not Found!n");

else
dir.fcnt--;
break;
case 3: printf("Enter name of the file to be searched:");
scanf("%s", &f);for(i=0;i<dir.fcnt;i++)
{
if (strcmp(f,dir.fname[i])==0)
{
printf("File Found!n");
flag=1;
break;
}
}
if (flag==0)
break;
case 4: if (dir.fcnt!=0)
for(i=0;i<dir.fcnt;i++)
printf("%sn", dir.fname[i]);
else printf("No files Present!");
break;
default: exit(0);
}
}
}

Output
Enter the name of the Directory: DIR1
MENU
1. Create File
2. Delete File
3. Search File
4. Display
5. Exit
Enter name of the file: file1
File Created
MENU
1. Create File
2. Delete File
3. Search File
4. Display
5. Exit
Enter name of the file: file2
File Created
MENU
1. Create File
2. Delete File
3. Search File
4. Display5. Exit
Enter name of the file:file3
File Created
MENU
1. Create File
2. Delete File
3. Search File
4. Display
5. Exit
file1
file2
file3
MENU
1. Create File
2. Delete File
3. Search File
4. Display

5. Exit
Enter name of the file to be searched: file4
File Not Found!
MENU
1. Create File
2. Delete File
3. Search File
4. Display
5. Exit
Enter name of the file to be deleted: file2
File Deleted!
MENU
1. Create File
2. Delete File
3. Search File
4. Display
5. Exit
file1
file3

12. Two- Level Directory

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
struct
{
char dname[10], fname[10][10];
int fcnt;
} dir[10];
void getfile(int i)
{
int j,ch,flag, flag1;
char f[30];
while(1)
{
flag=flag1=0;
printf("nDirectory: %s", dir[i].dname);
printf("nMENU n1.Create Filen2.Delete Filen3.Search Filen4.Displayn5.Exit
Directoryn");
scanf("%d", &ch);
switch(ch)
{
case 1:printf("Enter name of the file:");
scanf("%s", &f);
for(j=0;j<dir[i].fcnt;j++)
{
if (strcmp(f,dir[i].fname[j])==0)
{ printf("File of same name already exists. Create
againn");
flag1=1;
break;
}
}
if (flag1==0)
{
strcpy(dir[i].fname[j],f);
dir[i].fcnt++;
printf("File Createdn");
}
break;
case 2: printf("Enter name of the file to be deleted:");

scanf("%s", &f);for(j=0;j<dir[i].fcnt;j++)
{
{
printf("File Deleted!n");
strcpy(dir[i].fname[j], dir[i].fname[dir[i].fcnt-1]);
flag=1;
}
}
if (flag==0)
else
dir[i].fcnt--;
break;
case 3: printf("Enter name of the file to be searched:");
scanf("%s", &f);
{
{
printf("File Found!n");
flag=1;
break;
}
}
if (flag==0)
{
}
break;
case 4: if (dir[i].fcnt!=0)
{
printf("%sn", dir[i].fname[j]);
}
else printf("No files Present!n");
break;
default: return;
}
}
}
void main()
{

int i,ch,flag,flag1;
char f[30];
int dcnt=0;
while(1)
{flag=flag1=0;
printf("nMENU n1.Create Directoryn2.Delete Directoryn3.Search
Directoryn4.Choose Directoryn5.Displayn6.Exitn");
scanf("%d", &ch);
switch(ch)
{
case 1:printf("Enter name of the directory:");
scanf("%s", &f);
for(i=0;i<dcnt;i++)
{
if (strcmp(f,dir[i].dname)==0)
{ printf("Directory of same name already exists. Create
againn");
flag1=1;
break;
}
}
if (flag1==0)
{
strcpy(dir[i].dname,f);
dir[dcnt].fcnt=0;
dcnt++;
printf("Directory Createdn");
}
dir[dcnt].fcnt=0;
break;
case 2: printf("Enter name of the directory to be deleted:");
scanf("%s", &f);
for(i=0;i<dcnt;i++)
{
{
printf("Directory Deleted!n");
strcpy(dir[i].dname, dir[dcnt-1].dname);
flag=1;
}
}
if (flag==0)

printf("Directory Not Found!n");
else
dcnt--;
break;
case 3: printf("Enter name of the directory to be searched:");
scanf("%s", &f);
for(i=0;i<dcnt;i++)
{
{printf("Directory Found!n");
flag=1;
break;
}
}
if (flag==0)
{
}
break;
case 4: printf("Enter name of the directory:");
scanf("%s", &f);
for(i=0;i<dcnt;i++)
{
{
flag=1;
break;
}
}
if (flag==0)
{
}
else
getfile(i);
break;
case 5: if (dcnt!=0)
for(i=0;i<dcnt;i++)
{
printf("%sn", dir[i].dname);
}
else printf("No directories present!n");
break;

default: exit(0);
}
}
}

Output
MENU
1. Create Directory
2. Delete Directory
3. Search Directory
4. Choose Directory
5. Display
6. Exit
Enter name of the directory: DIR1
Directory Created
MENU
1. Create Directory
2. Delete Directory
3. Search Directory
4. Choose Directory
5. Display
6. Exit
Directory Created
MENU
1. Create Directory
2. Delete Directory
3. Search Directory
4. Choose Directory
5. Display
6. Exit
Enter your choice:4
Enter name of the directory:DIR2
MENU
1.Create File
2.Delete File
3.Search File
4.Display
5.Exit Directory
Enter your choice:1

File Created
MENU
1.Create File
2.Delete File
3.Search File
4.Display
5.Exit Directory
Enter your choice:1
File Created
MENU
1.Create File2.Delete File
3.Search File
4.Display
5.Exit Directory
Enter your choice:5
MENU
1.Create Directory
2.Delete Directory
3.Search Directory
4.Choose Directory
5.Display
6.Exit
Enter your choice : 4
MENU
1.Create File
2.Delete File
3.Search File
4.Display
5.Exit Directory
Enter your choice:4
No ﬁles Present!
MENU
1.Create File
2.Delete File
3.Search File
4.Display
5.Exit Directory
Enter your choice:5
MENU
1.Create Directory
2.Delete Directory

3. Search Directory
4. Choose Directory
5. Display
6. Exit

13. 2 Pass Assembler

PASS 1:
#include<stdio.h>
#include<math.h>
#include<string.h>
#include<stdlib.h>
void main()
{
char label[10], opcode[10], operand[10], mnemonic[10],code[10];
int locctr,length,start=0;
FILE *fp1, *fp2, *fp3, *fp4, *fp5;
fp1=fopen("input.txt", "r");
fp2=fopen("symbol.txt","w");
fp3=fopen("inter.txt", "w");
fp4=fopen("optab.txt","r");
fscanf(fp1, "%s%s%s", label, opcode, operand);
if (strcmp(opcode, "START")==0)
{
start=atoi(operand);
locctr=start;
fprintf(fp3, "%dt%st%st%sn",locctr, label,opcode, operand);
fscanf(fp1, "%s%s%s", label, opcode, operand);
} else locctr=0;
while(strcmp(opcode, "END")!=0)
{
fprintf(fp3, "%dt", locctr);
if (strcmp(label, "**")!=0)
{
if (strcmp(label,"-")!=0)
fprintf(fp2, "%st%dn", label,locctr);
fscanf(fp4, "%s%s", code,mnemonic);
while(strcmp(code, "END")!=0)
{
if (strcmp(opcode, code)==0)
{
locctr+=3;
break;
}
fscanf(fp4, "%s%s",code,mnemonic);
}
if(strcmp(opcode, "WORD")==0)
locctr+=3;

else if(strcmp(opcode, "RESW")==0)
locctr+=3*(atoi(operand));
else if(strcmp(opcode, "RESB")==0)
locctr+=atoi(operand);else if(strcmp(opcode, "BYTE")==0)
{
if (operand[0]=='X')
locctr+=1;
else if (operand[0]=='C')
locctr+=(strlen(operand)-3);
}
else locctr+=3;
}
fprintf(fp3, "%st%st%sn", label,opcode, operand);
fscanf(fp1, "%s%s%s", label,opcode, operand);
}
fprintf(fp3, "%dt%st%st%sn",locctr, label,opcode, operand);
fp5=fopen("length.txt","w");
length=locctr-start;
fprintf(fp5, "%d", length);
fclose(fp1);
fclose(fp2);
fclose(fp3);
fclose(fp4);
fclose(fp5);
}
PASS 2:
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
void main()
{
FILE *fp1,*fp2,*fp3,*fp4,*fp5;
char
opcode[10],operand[10],label[10],code[10],mnemonic[10],loc[10],len[10],l[10],laddr[10],sﬂag=0,s
tart[10
];
int slen,i;
fp1=fopen("inter.txt","r");
fp2=fopen("obj.txt","w");
fp3=fopen("length.txt","r");
fp4=fopen("optab.txt","r");
fp5=fopen("symbol.txt","r");
fscanf(fp1,"%s%s%s%s",loc,label,opcode,operand);

if(strcmp(opcode,"START")==0)
{
fscanf(fp3,"%s",len);
strcpy(start,len);
}
fprintf(fp2,"H^%s^%s^%sn",label,loc,len);
fprintf(fp2,"T^00%s^%s^",loc,len);
while(!feof(fp1))
{
rewind(fp4);if(strcmp(label,"-")==0)
{
fscanf(fp4,"%s%s",code,mnemonic);
while(!feof(fp4))
{
if(strcmp(opcode,code)==0)
{ fprintf(fp2,"%s",mnemonic);
fscanf(fp5,"%s%s",l,laddr);
rewind(fp5);
while(!feof(fp5))
{if(strcmp(operand,l)==0)
{
fprintf(fp2,"%s^",laddr);
sflag=1;
}
fscanf(fp5,"%s%s",l,laddr);
}
if(sflag==0)
fprintf(fp2,"0^");
sflag=0;
}
fscanf(fp4,"%s%s",code,mnemonic);
}
}
else if((strcmp(opcode,"WORD")==0)||(strcmp(opcode,"BYTE")==0))
{ if(strcmp(opcode,"WORD")==0)
fprintf(fp2,"00000%s^",operand);
else if((strcmp(opcode,"BYTE")==0))
{
slen=strlen(operand);
if(operand[0]=='X')
{ for(i=2;i<slen-1;i++)
fprintf(fp2,"%x",operand[i]);

}
else if(operand[0]=='C')
{ for(i=2;i<slen-1;i++)
fprintf(fp2,"%x",operand[i]);
}
}
}
}
fprintf(fp2,"nE^%s",start);
fclose(fp1);
fclose(fp2);
fclose(fp3);
fclose(fp4);
fclose(fp5);
}
INPUT FILE:
COPY START 2100
- LDA FIVE
- STA NUM1
- LDCH NUM2
- STCH C1
NUM1 RESW 2
FIVE WORD 3
NUM2 BYTE X'F1'
C1 RESB 1
- END -

OPTAB:
STA 0C
LDCH 50
LDA 00
STCH 54
END
SYMTAB:
NUM1 2112
FIVE 2118
NUM2 2121
C1 2122

INTERMEDIATE FILE:
2100 COPY START 2100
2100 - LDA FIVE
2103 - STA NUM1
2106 - LDCH NUM2
2109 - STCH C1
2112 NUM1 RESW 2
2118 FIVE WORD 3
2121 NUM2 BYTE X’F1’
2122 C1 RESB 1
2123 - END -

LENGTH:
23
OBJECT PROGRAM:
H^COPY^2100^23
T^002100^23^002118^0C2112^502121^542122^2122^000003^46f31
E^23

14. 2 Pass Macro Processor

PASS 1:
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
void main()
{
char mnem[10],operand[10],label[10];
FILE *fp1,*fp2,*fp3;
fp1=fopen("input.txt","r");
fp2=fopen("namtab.txt","w");
fp3=fopen("deftab.txt","w");
fscanf(fp1,"%s%s%s",label,mnem,operand);
while(strcmp(mnem,"MEND")!=0)
{
if(strcmp(mnem,"MACRO")==0)
{
fprintf(fp2,"%sn",label);
fprintf(fp3,"%st%sn",label,operand);
}
else
fprintf(fp3,"%st%sn",mnem,operand);
fscanf(fp1,"%s%s%s",label,mnem,operand);
}
fprintf(fp3,"%sn",mnem);
fclose(fp1);
fclose(fp2);
fclose(fp3);
}
PASS 2:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
void main()
{
char opcode[10],mne[10],oper[10],code[10],label[10],name[10],lab[10],mnem[10],opc[10];
int start,locctr,length,i;
FILE *fp1,*fp2,*fp3,*fp4,*fp5;
fp1=fopen("input.txt","r");
fp2=fopen("namtab.txt","r");fp3=fopen("deftab.txt","r");
fp4=fopen("argtab.txt","rw");
fp5=fopen("expand.txt","w");

fscanf(fp1,"%s%s%s",label,mne,oper);
while(strcmp(mne,"END")!=0)
{
if(strcmp(mne,"MACRO")==0)
{
while(strcmp(mne,"MEND")!=0)
}
else
{
fscanf(fp2,"%s",name);
if(strcmp(mne,name)==0)
{
length=strlen(oper);
for(i=0;i<length;i++)
{
if(oper[i]==',')
fprintf(fp4,"n");
else
fprintf(fp4,"%c",oper[i]);
}
fprintf(fp5,"%st%sn",mne,oper);
fscanf(fp3,"%st%s",lab,mnem);
fscanf(fp3,"%st%s",lab,mnem);
while(strcmp(lab,"MEND")!=0)
{
fprintf(fp5,"%st",lab);
if(mnem[0]=='&')
{
fscanf(fp4,"%s",opc);
fprintf(fp5,"%sn",opc);
}
fscanf(fp3,"%s%s",lab,mnem);
}
}
else
fprintf(fp5,"%st%st%sn",label,mne,oper);
}
}
fclose(fp1);
fclose(fp2);
fclose(fp3);

fclose(fp4);
fclose(fp5);
}
INPUT FILE:
EX1 MACRO &A,&B
- LDA &A
- STA &B
- MEND -
SAMPLE START 1000
- EX1 N1, N2
N1 RESW 1
N2 RESW 1
- END -

NAME TABLE:
EX1

DEFINITION TABLE:
EX1 &A,&B
LDA &A
STA &B
MEND
ARGUMENT TABLE:
N1
N2

OUTPUT :
SAMPLE START 1000
EX1 N1,N2
LDA N1
STA N2
N1 RESW 1
N2 RESW 1

15. Symbol Table

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
struct sym{
int key;
char name[20];
}ind[11];
void insert(int n, char nam[20])
{
FILE *f;
f=fopen("sym.txt","w");
int flag=0,x,i,j;
for(i=0;i<11;i++)
if(ind[i].key==0)
flag=1;
if(flag==0)
printf("nSymbol table is fulln");
else
{
x=n%11;
if(ind[x].key==0)
{
ind[x].key=n;
strcpy(ind[x].name,nam);
printf("nThe label is enteredn");
}
else
{
for(i=x,j=x;;)
{
if(ind[i].key==0)
{
ind[i].key=n;
strcpy(ind[i].name,nam);
break;
}
else if(ind[j].key==0)
{
ind[j].key=n;
strcpy(ind[j].name,nam);

break;
}
if(i!=10)
i++;if(j!=0)
j--;
if((i==10)&&(j==0))
break;
}
}
}
for(i=0;i<11;i++)
fprintf(f,"n%dt%s",ind[i].key,ind[i].name);
fclose(f);
}
void main()
{
int ch,addr,x,ﬂag=0;
char n[20],i;
for(i=0;i<11;i++)
ind[i].key=0;
do{
printf("nEnter your choice : n1.Create Labeln2.Search labeln3.Displayn4.Exit n");
scanf("%d",&ch);
switch(ch)
{
case 1: printf("nEnter the name of the label: ");
scanf("%s",n);
printf("Enter the address of the label: ");
scanf("%d",&addr);
insert(addr,n);
break;
case 2: printf("nEnter the name of the label to be searched: ");
scanf("%s",n);
for(i=0;i<11;i++)
{
if(strcmp(ind[i].name,n)==0)
{
printf("nLabel Foundn");
ﬂag=1;
break;
}
}

if(ﬂag==0)
printf("nLabel not foundn");
ﬂag=0;
break;
case 3: printf("nThe symbol table isn");
for(i=0;i<11;i++)
printf("n%dt%s",ind[i].key,ind[i].name);
break;
case 4 : printf("nExitingn");
break;
default : printf("nEnter the right choicen");
break;
}
}while(ch!=4);
}

Output
Enter your choice:
1. Create Label
2. Search label
3. Display
4. Exit
1
Enter the name of the label: hi
Enter the address of the label: 100
The label is entered
Enter your choice:
1. Create Label
2. Search label
3. Display
4. Exit
1
Enter the name of the label: bye
Enter the address of the label: 200
The label is entered
Enter your choice:
1. Create Label
2. Search label
3. Display
4. Exit
3

The symbol table is
0
100 hi
200 bye
0
0
0
0
0
0
0
Enter your choice:
1. Create Label
2. Search label
3. Display
4. Exit
4
Exiting

System Software /Operating System Lab Report

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System Software /Operating System Lab Report