OS Program Index

Operating System Programs

SCHEDULING ALGORITHMS - FIFO
SHORTEST JOB FIRST SCHEDULING
SEGMENTATION PRIORITY SCHEDULING
ROUND ROBIN SCHEDULING
DEKKER ‘S ALGORITHM
READER – WRITER PROBLEM
Memory Management
MEMORY ALLOCATION

MEMORY ALLOCATION

MEMORY ALLOCATION USING PAGING

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#include
#include “conio.h”
struct pstruct
{
int fno;
int pbit;
}ptable[10];

int pmsize,lmsize,psize,frame,page,ftable[20],frameno;

void info()
{
printf("\t\tMEMORY ALLOCATION USING PAGING\n");
printf("\t\t~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n\n");
printf("\n\nEnter the Size of Physical memory--> ");
scanf("%d",&pmsize);
printf("\n\nEnter the size of Logical memory--> ");
scanf("%d",&lmsize);
printf("\n\nEnter the partition size--> ");
scanf("%d",&psize);
frame = (int) pmsize/psize;
page = (int) lmsize/psize;
printf("\nThe Physical memory is divided into %d no.of frames\n",frame);
printf("\nThe Logical memory is divided into %d no.of pages",page);
}

void assign()
{
int i;
for (i=0;i {
ptable[i].fno = -1;
ptable[i].pbit= -1;
}
for(i=0; i ftable[i] = 32555;
for (i=0;i {
printf("\n\nEnter the Frame number where page %d must be placed: ",i);
scanf("%d",&frameno);
ftable[frameno] = i;
if(ptable[i].pbit == -1)
{
ptable[i].fno = frameno;
ptable[i].pbit = 1;
}
}
getch();
// clrscr();
printf("\t\tPAGE TABLE\n");
printf("\t\t~~~~~~~~~~\n");
printf("PageAddress FrameNo PresenceBit\n\n");
for (i=0;i printf("%d\t\t%d\t\t%d\n",i,ptable[i].fno,ptable[i].pbit);
/* printf("\n\n\n\tFRAME TABLE\n\n");
printf("FrameAddress PageNo\n\n");
for(i=0;i printf("%d\t\t%d\n",i,ftable[i]); */
}

void cphyaddr()
{
int laddr,paddr,disp,phyaddr,baddr;
getch();
// clrscr();
printf("\n\n\n\tProcess to create the Physical Address\n\n");
printf("\nEnter the Base Address: ");
scanf("%d",&baddr);
printf("\nEnter the Logical Address: ");
scanf("%d",&laddr);

paddr = laddr / psize;
disp = laddr % psize;
if(ptable[paddr].pbit == 1 )
phyaddr = baddr + (ptable[paddr].fno*psize) + disp;
printf("\nThe Physical Address where the instruction present: %d",phyaddr);
}
void main()
{
clrscr();
info();
assign();
cphyaddr();
getch();
}

MEMORY ALLOCATION
Memory Management
Output RW
READER – WRITER PROBLEM
DEKKER ‘S ALGORITHM
ROUND ROBIN SCHEDULING
SEGMENTATION
PRIORITY SCHEDULING
SHORTEST JOB FIRST SCHEDULING
SCHEDULING ALGORITHMS - FIFO

Memory Management

MEMORY MANAGEMENT

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#include”stdio.h”
#include”conio.h”
int i,n,p,bs[10],pro[10],mbs[10],blkno[10];
void getdata();
void ff();
void bf();
void wf();
void main()
{
int ch;
getdata();
clrscr();
do
{
clrscr();
//gotoxy(20,3);
printf("\t\tMEMORY MANAGEMENT\n");
printf("\t\t~~~~~~~~~~~~~~~~~\n\n");
printf("1.FirstFit\n2.BestFit\n3.WorstFit\nEnter your Choice: ");
scanf("%d",&ch);
getch();
clrscr();
switch (ch)
{
case 1: ff(); break;
case 2: bf(); break;
case 3: wf(); break;
}
getch();
}while(ch<4);>");;
scanf("%d",&n);
printf("\nEnter the block size of each partition\n");
for(i=1; i<=n; i++) { printf("\nEnter the Size of Block-%d : ",i); scanf("%d",&bs[i]); blkno[i] =i; } getch(); clrscr(); //gotoxy(25,5); printf("\t\tMEMORY ALLOCATION TECHNIQUES\n"); printf("\t\t~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n"); //gotoxy(20,7); printf("\tPROCESS INFORMATION\t"); printf("\nTotal Number of process--> ");
scanf("%d",&p);
printf("\nEnter the Size of each Process\n");
for(i=1;i<=n;i++) { printf("\nEnter the size of process-%d : ",i); scanf("%d",&pro[i]); } getch(); clrscr(); } void ff() { int flag,sum=0,j; //gotoxy(20,3); printf("\t\tFIRST FIT MEMORY ALLOCATION\n"); printf("\t\t~~~~~~~~~~~~~~~~~~~~~~~~~~~\n\n"); for (i=1; i<=n; i++) mbs[i] = bs[i]; printf("Pid SizeNeeded BlockSize BlockNo AllocatedSize RemainingSize \n\n"); for(i=1;i<=n;i++) { flag = 0; for(j=1;j<=n;j++) { if(mbs[j] >= pro[i] )
{
printf("%d\t %d\t%d\t\t%d\t\t%d\t %d\n\n",i,pro[i],mbs[j],j,pro[i],mbs[j]-pro[i]);
mbs[j]=mbs[j]-pro[i];
flag=1;
break;
}
}
if( !flag )
printf("\nProcess-%d is waiting\n\n",i);
}
for(i=1; i<= n; i++) sum = sum+mbs[i]; printf("\nTotal Number of Hole left: %d",sum); } void bf() { int flag,sum=0,j; //gotoxy(20,3); printf("\t\tBEST FIT MEMORY ALLOCATION\n"); printf("\t\t~~~~~~~~~~~~~~~~~~~~~~~~~~\n\n"); for (i=1; i<=n; i++) mbs[i] = bs[i]; printf("Pid SizeNeeded BlockSize BlockNo AllocatedSize RemainingSize \n\n"); for(i=1;i= mbs[j])
{
int t=mbs[i]; mbs[i] = mbs[j]; mbs[j] = t;
t=blkno[i]; blkno[i] = blkno[j]; blkno[j] = t;
}
for(i=1;i<=p;i++) { flag =0; for (j=1;j<=n;j++) { if(mbs[j] >= pro[i] )
{
printf("%d\t %d\t%d\t\t%d\t\t%d\t %d\n\n",i,pro[i],mbs[j],blkno[j],pro[i],mbs[j]-pro[i]);
mbs[j] = mbs[j] - pro[i];
sum = sum + mbs[j];
flag =1;
break;
}
}
if (!flag)
{
printf("\n Process-%d is waiting\n\n",i);
sum = sum + mbs[i];
}
}
printf("\n Total Number of Hole left: %d ",sum);
}

void wf()
{
int flag,sum=0,j;
//gotoxy(20,3);
printf("\t\tWORST FIT MEMORY ALLOCATION\n\n");
printf("\t\t~~~~~~~~~~~~~~~~~~~~~~~~~~~\n\n");
for (i=1; i<=n; i++) mbs[i] = bs[i]; printf("Pid SizeNeeded BlockSize BlockNo. AlocatedSize RemaingSize\n\n"); for(i=1;i= pro[i] )
{
printf("%d\t %d\t%d\t\t%d\t\t%d\t %d\n\n",i,pro[i],mbs[j],blkno[j],pro[i],mbs[j]-pro[i]);
mbs[j] = mbs[j] - pro[i];
sum = sum + mbs[j];
flag =1;
break;
}
}
if (!flag)
{
printf("\n Process-%d is waiting\n\n",i);
sum = sum + mbs[i];
}
}
printf("\n Total Number of Hole left: %d ",sum);
}

OUTPUT

Output RW

Output for READ-WRITER

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 1

Reader 1 reads the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 2

Cannot Write While Reader Reads the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 1

Reader 2 reads the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 3

Reader 2 Closes the File

Currently Only One Reader is Reading the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 3

Reader 1 Closes the File

Currently no Readers are using the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 2

Writer Write to the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 2

Writer Write to the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 2

Already One Writer is Writing to the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 1

Cannot Read while Writer Writes to the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 5

One Writer is Writing the File

1. READ FROM THE FILE
2. WRITE TO THE FILE
3. EXIT A READER
4. EXIT A WRITER
5. STATUS OF THE FILE
6. EXIT

ENTER THE CHOICE: 6

READER – WRITER PROBLEM

READER – WRITER PROBLEM

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#include”stdio.h”
int main()
{
typedef int semaphore;
semaphore sread=0,swrite=0;
int ch,r=0;
clrscr();
printf("\t\t\tREADER - WRITER PROBLEM\n");
printf("\t\t\t~~~~~~~~~~~~~~~~~~~~~~~~~\n");
do
{
printf("\n\t 1. READ FROM THE FILE");
printf("\n\t 2. WRITE TO THE FILE");
printf("\n\t 3. EXIT A READER");
printf("\n\t 4. EXIT A WRITER");
printf("\n\t 5. STATUS OF THE FILE");
printf("\n\t 6. EXIT");
printf("\n\n ENTER THE CHOICE:");
scanf("%d",&ch);
switch(ch)
{
case 1:if(swrite==0)
{
sread=1;
r=r+1;
printf("\n Reader %d reads the File\n",r);
}
else
printf("\n Cannot Read while Writer Writes to the File\n");
break;

case 2:if(sread==0 && swrite==0)
{
swrite=1;
printf("\n Writer Write to the File\n");
}
else
if(sread==1)
printf("\n Cannot Write While Reader Reads the File\n");
else if(swrite==1)
printf("\n Already One Writer is Writing to the File\n");
break;

case 3:if(r!=0)
{
printf("\n Reader %d Closes the File\n",r);
r=r-1;
if(r==0)
{
printf("\n Currently no Readers are using the File\n");
sread=0;
}
else if(r==1)
printf("\n Currently Only One Reader is Reading the File\n");
else
printf("\n Currently %d Readers are Reading the File\n",r);
}
break;
case 4: if(swrite==1)
{
printf("\n Writer Closes the File");
swrite=0;
}
else
printf("\n No Writer Writing to the File");
break;

case 5: if(sread==1)
{
if(r==1)
printf("\n One Reader is Reading the File");
else
printf("\n%d Readers are Reading the File",r);
}
else if(swrite==1)
printf("\n One Writer is Writing the File");
else
printf("\n File is not in Use\n");
break;
case 6: break;
}
}
while(ch!=6);
return 0;
}

OUTPUT

DEKKER ‘S ALGORITHM

DEKKER ‘S ALGORITHM

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#include”stdio.h”
#include"conio.h"
#include"time.h"
#include"type.h"
int turn;
int f0=0,f1=0;
int count=0;
void p0()
{
f0=1;
while(f1)
{
if(turn==1)
{
f0=0;
printf("\n Waiting time of p0 is starting \n");
while(turn==1)
{
if(count<5)
{
printf("\n p1 is in critical section \n");
printf("\n Do nothing \n");
count=count+1;
}
else
{
count=0;
turn=0;
f1=0;
}
}
f0=1;
}
}
printf("\n p0 is now u r in critical section \n");
turn=1;
f0=0;
}
void p1()
{
f1=1;
while(f0)
{
if(turn==0)
{
f1=0;
while(turn==0)
{
if(count<5)
{
printf("\n p0 is in critical section \n");
printf("\n do nothing \n");
count=count+1;
}
else
{
count=0;
turn=1;
f0=0;
}
}
f1=1;
}
}
printf("\n p1 is now u r in critical section \n");
turn=0;
f1=0;
}

void main()
{
int op;
do
{ clrscr();
printf("\n\t\t\t MUTUAL EXCLUSION PROBLEM \n");
printf(" \t\t\t ~~~~~~~~~~~~~~~~~~~~~~~~\n\n");
printf("\n 1: p0 in p1 wants \n");
printf("\n 2: p1 in p0 wants \n");
printf("\n 3: First p0 next p1 \n");
printf("\n 4: First p1 next p0 \n");
switch(op)
{
case 1:
f0=1;
turn=0;
p1();
break;
case 2:
f1=1;
turn=1;
p0();
break;
case 3:
p0();
p1();
break;
case 4:
p1();
p0();
break;
/* default;
break; */
}
printf("\n Enter u r choice-->");
scanf("%d",&op);
}
while(op<5);
}

ROUND ROBIN SCHEDULING

ROUND ROBIN SCHEDULING

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#include”stdio.h”
void main()
{
int ts,pid[10],need[10],wt[10],tat[10],i,j,n,n1;
int bt[10],flag[10],ttat=0,twt=0;
float awt,atat;
clrscr();
printf("\t\t ROUND ROBIN SCHEDULING \n");
printf("\t\t~~~~~~~~~~~~~~~~~~~~~~~ \n\n");
printf("Enter the number of Process-->");
scanf("%d",&n);

n1=n;
printf("\n Enter the Timeslice-->");
scanf("%d",&ts);
for(i=1;i<=n;i++) { printf("\n Enter the process ID %d-->",i);
scanf("%d",&pid[i]);
printf("\n Enter the Burst Time for the process-->");
scanf("%d",&bt[i]);
need[i]=bt[i];
}
for(i=1;i<=n;i++) { flag[i]=1; wt[i]=0; } while(n!=0) { for(i=1;i<=n;i++) { if(need[i]>=ts)
{
for(j=1;j<=n;j++)
{
if((i!=j)&&(flag[i]==1)&&(need[j]!=0))
wt[j]+=ts;
}
need[i]-=ts;
if(need[i]==0)
{
flag[i]=0;
n--;
}
}
else
{
for(j=1;j<=n;j++)
{
if((i!=j)&&(flag[i]==1)&&(need[j]!=0))
wt[j]+=need[i];
}
need[i]=0;
n--;
flag[i]=0;
}
}
}
for(i=1;i<=n1;i++)
{
tat[i]=wt[i]+bt[i];
twt=twt+wt[i];
ttat=ttat+tat[i];
}
awt=(float)twt/n1;
atat=(float)ttat/n1;

printf("\n\n ROUND ROBIN SCHEDULING ALGORITHM\n");
printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
printf("\n\n Process \t ProcessID \t BurstTime \t WaitingTime \t TurnaroundTime \n ");
for(i=1;i<=n1;i++)
{
printf("\n %5d \t\t %5d \t\t %5d \t\t %5d \t\t %5d \n", i,pid[i],bt[i],wt[i],tat[i]);
}

printf("\n The average Waiting Time=%3.2f",awt);
printf("\n\n The average Turn around Time=%4.2f",atat);
getch();
}

SEGMENTATION

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#include”stdio.h”
#include
void main()
{
int noseg,i,physaddr,temp1=0,digits=1,logicaddr,segno,disp,flag=0;
struct
{
int num;
int baseaddr;
int limit;
}segment[5];
clrscr();
printf("\n\nSEGMENTATION\n");
printf("~~~~~~~~~~~~~~\n\n");
printf("Enter the number of segments-->");
scanf("%d",&noseg);
for(i=1;i<=noseg;i++) { segment[i].num=i; printf("Segment Number-->%d",i);
printf("\nBase Segment in Physical Memory-->");
scanf("%d",&segment[i].baseaddr);
printf("\nLimit of Segment-->");
scanf("%d",&segment[i].limit);
}
printf("\nSEGNO\tBASEADDR\tLIMIT\n");
for(i=1;i<=noseg;i++) { printf("%d\t",segment[i].num); printf("%d\t",segment[i].baseaddr); printf("%d\t",segment[i].limit); printf("\n"); } do { while(1) { printf("\n\nEnter Logical Address-->");
scanf("%d",&logicaddr);
if(logicaddr>0)
{
while(temp1%d",segno);
printf("\n\nDisplacement-->%d",disp);
if(disp%d",logicaddr);
printf("\nPhysical Address-->%d",physaddr);
}
else
printf("Error");
break;
}
else
printf("Invalid Logical Address");
}
printf("To continue press 1-->");
scanf("%d",&flag);
}
while(flag==1);
getch();
}

PRIORITY SCHEDULING

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#include”stdio.h”
#include
void main()
{
int i,j,n,tat[10],bt[10],pid[10],pr[10],t,twt=0,ttat=0,wt[10];
float awt,atat;
clrscr();
printf("\n\t\t\tPRIORITY SCHEDULING\n");
printf("\n\nEnter the number of process:\t");
scanf("%d",&n);
for(i=0;ipr[j])
{
t=pr[i];
pr[i]=pr[j];
pr[j]=t;

t=bt[i];
bt[i]=bt[j];
bt[j]=t;

t=pid[i];
pid[i]=pid[j];
pid[j]=t;
}
}
}
tat[0]=bt[0];
wt[0]=0;
for(i=1;i {


wt[i]=wt[i-1]+bt[i-1];
tat[i]=wt[i]+bt[i];
}
printf("PID\tPRIORITY\tBURST TIME\tWAITING TIME\tTURN AROUND TIME\n");
for(i=0;i {
printf("\n%d\t%d\t\t%d\t\t%d\t\t%d",pid[i],pr[i],bt[i],wt[i],tat[i]);
}
for(i=0;i {
ttat=ttat+tat[i];
twt=twt+wt[i];
}
awt=(float)twt/n;
atat=(float)ttat/n;
printf("\n\nAverage Waiting Time:%4.2f",awt);
printf("\n\nAverage Turn Around Time:%4.2f",atat);
getch();
}

SHORTEST JOB FIRST SCHEDULING

SJF

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#include”stdio.h”
void main()
{
int i,j,k,n,sum,wt[10],tt[10],twt,ttat;
int t[10],p[10];
float awt,atat;
clrscr();
printf("\t\t\t(b) SHORTEST JOB FIRST SCHEDULING\n ");
printf("\t\t ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
printf("Enter number of process\n");
scanf("%d",&n);

for(i=0;i",i);
scanf("\n %d",&t[i]);
}

for(i=0;it[k])
{
int temp;
temp=t[i];
t[i]=t[k];
t[k]=temp;

temp=p[i];
p[i]=p[k];
p[k]=temp;
}
}
printf("\n\n SHORTEST JOB FIRST SCHEDULING ALGORITHM");
printf("\n ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
printf("\n PROCESS ID \t BURST TIME \t WAITING TIME \t TURNAROUND TIME \n\n");
wt[0]=0;
for(i=0;i {
sum=0;
for(k=0;k {
wt[i]=sum+t[k];
sum=wt[i];
}
}
for(i=0;i {
tt[i]=t[i]+wt[i];
}
for(i=0;i {
printf("%5d %d %5d %5d \n\n",p[i],t[i],wt[i],tt[i]);
}
twt=0;
ttat=t[0];
for(i=1;i {
twt=twt+wt[i];
ttat=ttat+tt[i];
}
awt=(float)twt/n;
atat=(float)ttat/n;

printf("\n AVERAGE WAITING TIME %4.2f",awt);
printf("\n\n AVERAGE TURN AROUND TIME %4.2f",atat);
getch();
}
}

SCHEDULING ALGORITHMS - FIFO

FIRST COME FIRST SERVE (FIFO)

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#include”stdio.h”
void main()
{
int i,n,sum,wt,tat,twt,ttat;
int t[10];
float awt,atat;
clrscr();
printf("\t\t\t\tSCHEDULING ALGORITHMS\n");
printf("\t\t ~~~~~~~~~~~~~~~~~~~~~\n");
printf("\t\t\tFIRST COME FIRST SERVE\n");
printf("Enter number of process:\n");
scanf("%d",&n);
for(i=0;i",i+1);
scanf("\n %d",&t[i]);
}
printf("\n\n FIRST COME FIRST SERVE SCHEDULING ALGORITHM\n ");
printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ \n");
printf("\n ProcessID \t WaitingTime \t TurnAroundTime \n\n");
printf(" 1 0 %d \n",t[0]);
sum=0;
twt=0;
ttat=t[0];
for(i=1;i

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