CN LAB

Computer Networks

1. Character Stuffing
2. Bit Stuffing
3. Cyclic Redundancy Check
4. Dijkstra's Algorithms 
5. Distance Vector Routing Algorithm
6. RSA Algorithm

Operating Systems

Operating Systems

CPU Scheduling Algorithms

1. First Come First Serve (FCFS)
2. Shortest Job First (SJF)  [No pre-emption, with arrival times] Shortest Job First (SJF) [Pre-emptive, with arrival times]
3. Round Robin
4. Priority

Page Replacement Algorithms

1. First In First Out (FIFO)
2. Least Recently Used (LRU)
3. Optimal

Page Replacement Algorithm

FIFO Page Replacement Algorithm

 //FIFO PAGE REPLACEMENT ALGORITHM  
 #include <stdio.h>  
 #include <conio.h>  
 int main()  
 {  
   int n, rss, fa[20], rsa[50]; //n-No_of_Frames  
   //rss->Reference_String_Size::fa->Frame_Array  
   //rsa->Reference_String_Array::ta->Temporary_Array  
   int i,j,k,pfc=0,npf, cp=0;  
   //cp->Current_Position :: ff->Frames_Filled ::pfc->Page_Fault_Count  
   //npf:NO_Page_Faults [0-False, 1-True]  
   printf("Enter number of frames: ");  
   scanf("%d", &n);  
   printf("Enter number of pages in reference string: ");  
   scanf("%d", &rss);  
   printf("Enter Reference string:\n");  
   for(i=0; i<rss; i++)  
     scanf("%d",&rsa[i]);  
   for(i=0;i<n;i++)  
     fa[i]=-1;  
   printf("\nCURRENT_PAGE\t\tPAGES_IN_FRAME\t\tPAGE_FAULT_OCCURED?\n");  
   for(i=0; i<rss; i++)  
   {  
     printf("\n\t%d\t\t",rsa[i]);  
     npf=0;  
     for(j=0;j<n;j++)  //Checking for the page in FRAME ARRAY  
     {  
       if(fa[j]==rsa[i])  
       {  
         npf = 1;  
         printf("\t\t\t\tNO");  
         break;  
       }  
     }  
     if(npf==0)   // if page fault occurs  
     {  
       pfc++;  
       fa[cp] = rsa[i];  
       cp=(cp+1)%n;  
       for(j=0;j<n;j++)  
         printf("%d\t",fa[j]);  
       printf("\tYES");  
     }  
   }  
   printf("\nTotal no of pagefaults: %d",pfc);  
   return 0;  
 }  

LRU Page Replacement Algorithm





 //LRU PAGE REPLACEMENT ALGORITHM  
 #include <stdio.h>  
 #include <conio.h>  
 int main()  
 {  
   int n, rss, fa[20], rsa[50], ta[20]; //n-No_of_Frames  
   //rss->Reference_String_Size::fa->Frame_Array  
   //rsa->Reference_String_Array::ta->Temporary_Array  
   int i,j,k,pfc=0,npf, cp;  
   //cp->Current_Position ::pfc->Page_Fault_Count  
   //npf:NO_Page_Faults [0-False, 1-True]  
   printf("Enter number of frames: ");  
   scanf("%d", &n);  
   printf("Enter number of pages in reference string: ");  
   scanf("%d", &rss);  
   printf("Enter Reference string:\n");  
   for(i=0; i<rss; i++)  
     scanf("%d",&rsa[i]);  
   for(i=0;i<n;i++)  
     fa[i]=-1;  
   for(i=0;i<n;i++)  
     ta[i]=n-(i+1);  
   printf("\nCURRENT_PAGE\t\tPAGES_IN_FRAME\t\tPAGE_FAULT_OCCURED?\n");  
   for(i=0; i<rss; i++)  
   {  
     printf("\n\t%d\t\t",rsa[i]);  
     npf=0;  
     for(j=0;j<n;j++)  //Checking for the page in FRAME ARRAY  
     {  
       if(fa[j]==rsa[i])  
       {  
         npf = 1;  
         for(k=0;k<n;k++)  
           ta[k]++;  
         ta[j]=0;  
         printf("\t\t\t\tNO");  
         break;  
       }  
     }  
     if(npf==0)   // if page fault occurs  
     {  
       pfc++;  
       cp=0;  
       for(j=1;j<n;j++)  
         if(ta[cp]<ta[j])  
           cp=j; //cp->current position  
       fa[cp] = rsa[i];  
       for(k=0;k<n;k++)  
         ta[k]++;  
       ta[cp]=0;  
       for(j=0;j<n;j++)  
         printf("%d\t",fa[j]);  
       printf("\tYES");  
     }  
   }  
   printf("\nTotal no of pagefaults: %d",pfc);  
   return 0;  
 }