Simulate all Page Replacement Algorithms

a) FIFO Page Replacement Algorithm

#include<stdio.h>#include<conio.h>int str[30],z,count,fs,p[100],pf=0;main(){ int i,j,k,temp; printf("\n Enter the No.of frames:"); scanf("%d",&fs); printf("\n Enter string (-1 to stop):"); i=0; while(1) { scanf("%d",&temp); if(temp==-1) break; str[i++]=temp; } count=i; for(i=0;i<fs;i++) p[i]=-1; printf("\n\t Pages \t Frames"); i=j=0; while(i<count) { if(!check(str[i])) { pf++; p[j]=str[i]; j=(j+1)%fs; } printf("\n\t <%d> \t",str[i]); for(k=0;k<fs;k++) if(p[k]!=-1) printf("%3d",p[k]); i++; } z=pf-fs; printf("\n\t Page Faults:%d",z); } check(int key) { int i; for(i=0;i<fs;i++) if(key==p[i]) return 1;

return 0; }

OUTPUT:1) Enter the No.of frames:3 Enter string (-1 to stop):2 3 2 1 5 2 4 5 3 2 5 2 -1 Pages Frames <2> 2 <3> 2 3 <2> 2 3 <1> 2 3 1 <5> 5 3 1 <2> 5 2 1 <4> 5 2 4 <5> 5 2 4 <3> 3 2 4 <2> 3 2 4 <5> 3 5 4 <2> 3 5 2 Page Faults:6

b) LRU Page Replacement Algorithm

#include<stdio.h>#include<conio.h>int str[30],count,fs,p[100],pf;main(){ int i,j,k,z,temp; printf("\n Enter the No.of frames:"); scanf("%d",&fs); printf("\n Enter string (-1 to stop):"); i=0; while(1) { scanf("%d",&temp); if(temp==-1) break; str[i++]=temp; } count=i; for(i=0;i<fs;i++) p[i]=-1; printf("\n Pages \t\t Frames"); i=0; while(i<count) { if(!check(str[i])) { pf++; j=lru(i); p[j]=str[i]; } printf("\n %3d \t\t",str[i]); for(k=0;k<fs;k++) if(p[k]!=-1)printf("%3d",p[k]); i++; } z=pf-fs; printf("\n\n Page Faults:%d",z); } check(int key) { int i; for(i=0;i<fs;i++) if(key==p[i]) return 1; return 0;

} lru(int pos) { int i,j=0,r=0; for(i=0;i<fs;i++) { if(p[i]==-1) return i; if(rec(i,pos)>=r) { j=i; r=rec(i,pos); } } return j; } rec(int fn,int pn) { int i,c=0; for(i=pn-1;i>=0;i--) { c++; if(p[fn]==str[i]) return c; } }

OUTPUT 1) Enter the No. of frames: 3 Enter string (-1 to stop):2 3 2 1 5 2 4 5 3 2 5 2 -1 Pages Frames 2 2 3 2 3 2 2 3 1 2 3 1 5 2 5 1 2 2 5 1 4 2 5 4 5 2 5 4 3 3 5 4 2 3 5 2 5 3 5 2 2 3 5 2

Page Faults:4

c) LFU page replacement Algorithm

#include<stdio.h>int i,j=1,s,k,l,re[30],p[10],ch,no,nr,c,a1=0,a,line=6,nk;struct{

int st,l,ps,pos;}opr;main(){

clrscr();printf("Enter length of reference string:");scanf("%d",&nr);printf(" Enter reference string:");for(i=1;i<=nr;i++)scanf("%d",&re[i]);printf("\n Enter number of frames:");scanf("%d",&no);clrscr();for(i=1;i<=no;i++)p[i]=-1;opr.st=100;for(i=1;i<=nr;i++){

a1=0;opr.st=100;opr.pos=100;for(c=1;c<=no;c++)if(re[i]==p[c])a1++;if(a1==0){

if(j<=no){

p[j]=re[i];j++;

}else{

for(k=1;k<=no;k++){

a=0;for(ch=i-1;ch>0;ch--){

if(p[k]==re[ch]){

a++;nk=ch;

}

}if(a>1){

if(opr.st>a){

opr.st=a;opr.ps=k;

}elseif(opr.st==a){

if(opr.pos>ch)opr.ps=k;

}}elseif(a==1){

if(opr.pos>nk){

opr.pos=nk;opr.ps=k;opr.st=a;

}}

}p[(opr.ps)]=re[i];

}}display(no,p,i);

}printf("\n");getch();

}display(int no,int p[],int i){

int k;if(i==1){

printf("\t\t\t");for(k=1;k<=no;k++)printf("_ _");

}printf("\n%d",re[i]);gotoxy(25,line++);for(k=1;k<=no;k++){ printf("|");

printf("_");if(p[k]!=-1)

printf("%d",p[k]);elseprintf(" ");printf("_");

} printf("|"); }

OUTPUT:

Least frequently used

Enter no of frame 3

Enter no of pages  4

Enter  page sequence 4 5 8

400F

450F

458F

No of page faults  3

3.Simulate all File Allocation Strategies

a) Sequential file allocation

#include<stdio.h>#include<conio.h>#include<stdlib.h>typedef struct{

int bno,flag;}block;

block b[200];void main(){

int rnum();

int n,p[30],i,j,r,k[20][20],s,s1;printf("\n input");

printf("\n enter no of files");scanf("%d",&n);printf("\n-------------------------------");printf("\n enter memory requirements");printf("\n------------------------------");for(i=1;i<=n;i++){ printf("\n enter %d file requirements:",i); scanf("%d",&p[i]);}for(i=1;i<=n;i++){ s1=rnum(); j=0; for(s=s1;s<(s1+p[i]);s++) {

j=j+1;b[s].bno=s;b[s].flag=1;k[i][j]=s;

}}printf("\n output");printf("\n ---------------------------------");printf("\n program blocka allocated");printf("\n----------------------------------");for(i=1;i<=n;i++){

printf("%5d\t",i); for(j=1;j<=p[i];j++)

printf("%5d",k[i][j]); printf("'\n");}printf("\n------------------------------------");

printf("\n allocated blocks:");printf("\n-----------------------------------");for(i=1;i<=200;i++)

if(b[i].flag==1)printf("%5d\t",b[i].bno);

}int rnum(){

int i,k=0;for(i=1;i<=200;i++){

k=rand()%200;if(k%2==0) k=k+10;if(b[k].flag!=1) break;return k;

}}

OUTPUT:

Enter the no of input files : 3Input the requirements:Enter the no of blocks needed in file 1: 2Enter the no of blocks needed in file2 :4Enter the no of blocks needed in file3: 3AllocationAllocate for file1: 8386Allocate for file2: 77159335Allocate for file3:924921

b) Indexed File allocation

#include<stdio.h>#include<conio.h>#include<stdlib.h>struct block{ int bno,flag;};struct block b[100];int rnum();

void main(){ int p[10],r[10][10],ab[10],i,j,n,s; printf("\n INPUT"); printf("enter no of files:"); scanf("%d",&n); for(i=1;i<=n;i++) { printf("\n enter the size of block %d:",i); scanf("%d",&p[i]); } for(i=1;i<=n;i++) { s=rnum(); ab[i]=s; for(j=0;j<p[i];j++) { s=rnum(); r[i][j]=s; }}printf("\n output:"); for(i=1;i<=n;i++){ printf("\n file %d \n block %d contains:",i,ab[i]); for(j=0;j<p[i];j++) { printf("%6d",r[i][j]); }}}int rnum(){int k=0,i; for(i=1;i<=100;i++) { k=rand()%100;

if(b[k].flag!=-1)

break; }return k;}

OUTPUT:

Enter the no of files: 3Enter the memory requirements:

Enter the 1 file requirement: 3Enter the 2 file requirement: 2Enter the 3 file requirement: 4

Program blocks allocated1 70 71 722 115 1163 212 213 214 215Allocated blocks70 71 72 115 116 212 213 214 215

c) Linked File Allocation

#include<stdio.h>#include<conio.h>#include<stdlib.h>typedef struct{

int bno,flag,bn[20];}block;

block b[100],b1;void main(){

int rnum();int p[30],kk[20],i,n,t,s1,s,r,j,c=1;printf("\n enter no of i/p files");scanf("%d",&n);printf("\n input the requirements");for(i=1;i<=n;i++){

printf("\n enter the no of blocks needed for file%d",i);scanf("%d",&p[i]);

}t=1;for(i=1;i<=n;i++){ for(j=1;j<=p[i];j++) {

s=rnum();b[s].flag=1;b[c].bno=s;r=p[i]-1;kk[i]=s;t=1;c++;

}}while(r!=0){

s1=rnum();b[s].bn[t]=s1;b[s1].flag=1;b[c].bno=s1;r=r-1;t=t+1;c++;

}printf("\n allocation:\n");

c=1;for(i=1;i<=n;i++){ printf("\n allocated for file%d",i); for(j=1;j<=p[i];j++) {

if(j==1){ printf("%3d",b[c].bno); c++;}else{ printf("---->%3d",b[c].bno); c++;}

} printf("\n");}

}int rnum(){

int k=0,i;for(i=1;i<=100;i++){

k=rand()%100;if(b[k].flag!=1)break;

}return k;

}

OUTPUT:

Enter the no of files 3Enter the size of block 1 2 34 3 2File 1 Block 83 contains 86 77 15 93File 2 Block 85 contains 86 92 49File 3 Block 21 contains 62 27

4. Simulate all File Organization Techniques

a) Single level directory#include<stdio.h>#include<conio.h>#include<stdlib.h>#include<graphics.h>void main(){

int gd,gm,count,i,j,mid,cir_x;char fname[10][20];gd=DETECT;clrscr();initgraph(&gd,&gm,"c:/turboc");cleardevice();setbkcolor(GREEN);puts("\n Enterno.of files do u have?");scanf("%d",&count);for(i=0;i<count;i++){

cleardevice();setbkcolor(GREEN);printf("Enter file %d name ",i+1);scanf("%s",fname[i]);setfillstyle(1,MAGENTA);mid=640/count;cir_x=mid/3;bar3d(270,100,370,150,0,0);settextstyle(2,0,4);settextjustify(1,1);outtextxy(320,125,"Root Directory");setcolor(BLUE);for(j=0;j<=i;j++,cir_x+=mid){

line(320,150,cir_x,250);fillellipse(cir_x,250,30,30);outtextxy(cir_x,250,fname[i]);

}getch();

}}

OUTPUT:

b) Two level Directory

//two level directory structure#include<stdio.h>#include<conio.h>#include<graphics.h>#define SX 250#define SY 200#define BL 30#define BW 15#define SY1 250int SX1=100;int n,m[10];char a[10][10];int cols[]={2,5,1,3,4,6,8,7,9};typedef struct{ char name[10]; struct { char file[10]; }k[10];}file_info;file_info f[10];void readfiles(){ int i,j; printf("\nEnter no. of directories:"); scanf("%d",&n); for(i=0;i<n;i++) { printf("Enter %d directory:",i+1); scanf("%s",&f[i].name); printf("enter no.of files:"); scanf("%d",&m[i]); for(j=0;j<m[i];j++) { printf("enter %d file name:",j+1); scanf("%s",&f[i].k[j].file); } }}void fillspace(){ int x1,y1,i,j; outtextxy(70,205,"Directory"); outtextxy(100,255,"Files"); for(i=0;i<n;i++) { setfillstyle(1,cols[i]);

x1=SX+(i%10)*50; y1=SY+(i/10)*40; bar(x1,y1,x1+BL+20,y1+BW); outtextxy(x1+BL/4,y1+BW/4,f[i].name); line(x1+BL/2,y1+BW,SX1+50,SY1); SX1=SX1+50; for(j=0;j<m[i];j++) { setfillstyle(1,cols[i]); x1=SX1+(j%10)*40; y1=SY1+(j/10)*40; bar(x1,y1,x1+BL+10,y1+BW); outtextxy(x1+BL/4,y1+BW/4,f[i].k[j].file); line(x1+BL/2,y1+BW,x1+BL/2,y1+50); circle(x1+BL/2,y1+60,7); } SX1=SX1+100; }}void main(){ int gm,gd=DETECT; initgraph(&gd,&gm,"c:\\tc\\bgi"); readfiles(); cleardevice(); getch(); fillspace(); getch(); closegraph();}

5.Interprocess Communication

a) Pipes

#include<stdio.h> #include<string.h> #include<stdlib.h> #include<error.h> #define MAXBUFF 1024 main() { int childpid,pipe1[2],pipe2[2]; if(pipe(pipe1)<0||pipe(pipe2)<0) printf("error"); if((childpid=fork())<0) { printf("error"); } else if(childpid>0) { close(pipe1[0]); close(pipe2[1]); client(pipe2[0],pipe1[1]); while(wait((int *)0)!=childpid) close(pipe1[1]); close(pipe2[0]); exit(1); } else { close(pipe1[1]); close(pipe2[0]); server(pipe1[0],pipe2[1]); close(pipe1[0]); close(pipe2[1]); } } client(readfd,writefd) int readfd,writefd; { char buff[MAXBUFF]; int n; if(fgets(buff,MAXBUFF,stdin)==NULL) printf("client filename read error"); n=strlen(buff); if(buff[n-1]=='\n') n--; if(write(writefd,buff,n)!=n)

printf("client filename error"); while((n=read(readfd,buff,MAXBUFF))>0) if(write(1,buff,n)!=n) printf("client data write error"); if(n>0) printf("client: data read errror"); } server(readfd,writefd) int readfd,writefd; { char buff[MAXBUFF]; int n,fd; if((n=read(readfd,buff,MAXBUFF))<0) printf("srever filename read error"); buff[n]='\0'; if((fd=open(buff,0))<0) { n=strlen(buff); if(write(writefd,buff,n)!=n) printf("server :error msg"); } else { while((n=read(fd,buff,MAXBUFF))>0) if(write(writefd,buff,n)!=n) printf("server data write error"); if(n>0) printf("server read error"); } }

OUTPUT: vi a.txt welcome to NP ]$ ./a.out a.txt welcome to NP

b) FIFO

#include<stdlib.h> #include<sys/types.h> #include<stdio.h> #include<sys/stat.h> #include<string.h> #include<sys/wait.h> #define FIFO1 "tmp/fifo1.c" #define FIFO2 "tmp/fifo2.c" #define PERM 0666 main() { int chpid,rfd,wfd; mknod(FIFO1,S_IFIFO|PERM,0); mknod(FIFO2,S_IFIFO|PERM,0); if(chpid=fork()>0) { wfd=open(FIFO1,1); rfd=open(FIFO2,0); client(rfd,wfd); while(wait((int *)0)!=chpid) close(rfd); close(wfd); exit(1); } }

OUTPUT: hello HELLO :from server

c) Semaphores

#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <errno.h>#include <sys/types.h>#include <sys/ipc.h>#include <sys/sem.h>

#define MAX_RETRIES 10

union semun { int val; struct semid_ds *buf; ushort *array;};

int initsem(key_t key, int nsems) { int i; union semun arg; struct semid_ds buf; struct sembuf sb; int semid;

semid = semget(key, nsems, IPC_CREAT | IPC_EXCL | 0666);

if (semid >= 0) { sb.sem_op = 1; sb.sem_flg = 0; arg.val = 1;

printf("press return\n"); getchar();

for(sb.sem_num = 0; sb.sem_num < nsems; sb.sem_num++) { if (semop(semid, &sb, 1) == -1) { int e = errno; semctl(semid, 0, IPC_RMID); errno = e; return -1; } }

} else if (errno == EEXIST) { int ready = 0;

semid = semget(key, nsems, 0); if (semid < 0) return semid; arg.buf = &buf; for(i = 0; i < MAX_RETRIES && !ready; i++) { semctl(semid, nsems-1, IPC_STAT, arg); if (arg.buf->sem_otime != 0) { ready = 1; } else { sleep(1); } } if (!ready) { errno = ETIME; return -1; } } else { return semid; }

return semid;}

int main(void){ key_t key; int semid; struct sembuf sb; sb.sem_num = 0; sb.sem_op = -1; sb.sem_flg = SEM_UNDO;

if ((key = ftok("semdemo.c", 'J')) == -1) { perror("ftok"); exit(1); }

if ((semid = initsem(key, 1)) == -1) { perror("initsem"); exit(1); }

printf("Press return to lock: ");

getchar(); printf("Trying to lock...\n");

if (semop(semid, &sb, 1) == -1) { perror("semop"); exit(1); }

printf("Locked.\n"); printf("Press return to unlock: "); getchar();

sb.sem_op = 1; / if (semop(semid, &sb, 1) == -1) { perror("semop"); exit(1); } printf("Unlocked\n"); return 0;}

OUTPUT:

d) Message Queues/*server*/

#include<sys/types.h> #include<sys/ipc.h> #include<sys/msg.h> #include<stdio.h> #include<stdlib.h> #include<string.h> #define BUFSZ 4096 struct msg { 10 long int type; char text[BUFSZ]; }; int main() { struct msg data; int msgid; char buff[BUFSZ]; msgid=msgget((key_t)4321,0666|IPC_CREAT); while(1) { 21 printf("\n enter some data:\n\n"); fgets(buff,BUFSZ,stdin); data.type=1; strcpy(data.text,buff); msgsnd(msgid,(void *)&data,BUFSZ,0); exit(1); } 28 }

OUTPUT: enter some data hai

/*client*/ #include<sys/types.h> #include<sys/ipc.h> #include<sys/msg.h> #include<stdio.h> #include<stdlib.h> #include<string.h> #define MSGKEY1 4321L #define MAX 5700

typedef struct msgbuf{ long mtype; char mtext[MAX]; }my_msgbuff; main() { my_msgbuff buffer; int msgID,myID; int temp; if((msgID=msgget(MSGKEY1,0666|IPC_CREAT))<0) { perror("error getting msg queue"); exit(1); } if(msgrcv(msgID,&buffer,sizeof(buffer),0L,0)<0) { perror("error receiving msg from queue"); exit(1); } printf("\n msg read from queue:\n\n"); printf("MESSAGE:%s\n",buffer.mtext); while(msgsnd(msgID,&buffer,sizeof(buffer.mtext),0)>0); if(msgctl(msgID,IPC_RMID,0)<0) { perror("error detecting msg queue"); exit(1); } msgctl(myID,IPC_RMID,0); exit(0); }

OUTPUT: msg read from queue: MESSAGE:hai

e) Shared Memory

/*server*/ #include<sys/types.h> #include<sys/ipc.h> #include<sys/shm.h> #include<stdio.h> #include<stdlib.h> #define SHMSZ 27 main() { char c; int shmid; key_t key; char *shm,*s; key=1202; if((shmid=shmget(key,SHMSZ,IPC_CREAT|0666))<0) { perror("shmat"); exit(1); } if((shm=shmat(shmid,NULL,0))==(char *)-1) { perror("shmat"); exit(1); } s=shm; for(c='a';c<='z';c++) *s++=c; *s=NULL; while(*shm!='*') sleep(1); exit(0); }/*client*/

#include<sys/types.h> #include<sys/ipc.h>

#include<sys/shm.h> #include<stdio.h> #include<stdlib.h> #define SHMSZ 27 main() { int shmid; key_t key; key=1202; char *s,*shm; if((shmid=shmget(key,SHMSZ,0666))<0) { perror("shmget"); exit(1); } if((shm=shmat(shmid,NULL,0))==(char *)-1) { perror("shmat"); exit(1); } for(s=shm;*s!=NULL;s++) putchar(*s); putchar('\n'); *shm='*'; exit(0); }

OUTPUT: abcdefghijklmnopqrstuvwxyz

Banker’s Algorithm for Deadlock avoidance and Prevention

#include<stdio.h> #include<conio.h> int C[4][3],A[4][3],RQ[4][3],V[3],R[3],K[4],sum=0,np,nr; main() { void fun(); int i,j,count=0,pcount=0; clrscr(); printf("\nEnter the total number of resources : "); scanf("\n%d",&nr); for(i=0;i<nr;i++) { printf("\nEnter the no of resources int R%d : ",i+1); scanf("%d",&R[i]); } printf("\nEnter the no of processes to be executed : "); scanf("%d",&np); printf("\nEnter the claim matrix:\n"); for(i=0;i<np;i++) for(j=0;j<nr;j++) scanf("%d",&C[i][j]); printf("\nEnter the allocation matrix:\n"); for(i=0;i<np;i++) for(j=0;j<nr;j++) scanf("%d",&A[i][j]); for(i=0;i<np;i++) for(j=0;j<nr;j++) RQ[i][j] = C[i][j] - A[i][j]; fun(); for(i=0;i<np;i++) { count=0; f(K[i] == i+1) continue;

for(j=0;j<nr;j++) { if(V[j] >= RQ[i][j]) count++; } if(count == nr) { K[i] = i+1; for(j=0;j<nr;j++)

C[i][j] = A[i][j] = RQ[i][j] = 0;pcount++;count = 0;i=-1;fun();

} }

if(pcount == np) printf("\nThere is no chance of deadlock.\nIt is a safe state."); else printf("\nThere is a chance of deadlock.\nIt isn't a safe state."); getch(); }

void fun() { int i1,j1; for(i1=0;i1<nr;i1++) { for(j1=0;j1<np;j1++) { sum = sum + A[j1][i1]; } V[i1] = R[i1] - sum; sum = 0; } }

OUTPUT Enter the total number of resources 2 Enter the total number of resources in R1 4

Enter the total number of resources in R2 5 Enter the total number of processes to be executed 4 Enter the claim matrix 2 4 6 2 Enter the allocation matrix 1 0 1 1 There is a chance of deadlock It is not a safe state