Adding C program to simulate LRU, LFU and MRU caches'

Author: shashankvhegde

CacheSimulation.c

@@ -0,0 +1,282 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct node {
+	int data;
+	int freq;
+	struct node* next;
+	
+}Nodetype;
+
+Nodetype* makenode(int data){
+	
+	Nodetype *nptr;
+	nptr = (Nodetype*)malloc(sizeof(Nodetype));
+	nptr->data = data;
+	nptr->freq = 1;
+	nptr->next = NULL;
+	
+	return nptr;
+	
+}
+
+void traverse(Nodetype *lptr){
+	
+	/*Prints node data*/
+	
+	Nodetype *nptr;
+	nptr = lptr;
+	while(nptr !=  NULL){
+		printf("Data: ");
+		printf("%d ",nptr->data);
+		printf("Frequency: ");
+		printf("%d\t",nptr->freq);
+		nptr = nptr->next;
+	}
+	printf("\n");
+}
+
+
+int getlength(Nodetype *lptr){
+	
+	/*Return Length of the Cache*/
+	
+	int length = 0;
+	Nodetype *nptr;
+	nptr = lptr;
+	
+	while(nptr !=  NULL){
+		
+		length++;
+		nptr = nptr->next;
+	}
+	
+	return length;
+}
+
+
+Nodetype* exists(Nodetype *lptr,int data){
+	
+	
+	/*Checks if a node with given data exists in cache or not */
+	
+	Nodetype *nptr;
+	nptr = lptr;
+	int found = 0;
+	
+	while(nptr != NULL && found == 0){
+		
+	
+		if(nptr->data == data){
+		
+			found = 1;
+		}
+		else{
+			nptr = nptr->next;
+		}
+		
+	}	
+	
+	return nptr;
+	
+}
+
+
+Nodetype* InsertAtEnd(Nodetype *lptr, int data){
+	
+	/*Creates a node and inserts it at the end*/
+	
+	Nodetype *nptr, *n;
+	nptr = lptr;
+	n = makenode(data);
+	
+	if(nptr != NULL){
+				
+		while(nptr->next != NULL){
+			
+			nptr = nptr->next;
+
+		}
+		nptr->next = n;	
+			
+	}
+	else{
+		/*This case arrives only at the start where you  start creating the cache*/
+		lptr = n;
+		
+	}
+
+	return lptr;
+	
+}
+
+Nodetype* AppendAtEnd(Nodetype *lptr, Nodetype *nptr){
+	
+	/*Appends a node which exists in cache at the end */
+	
+	Nodetype *prev, *ptr, *last;
+	prev = NULL;
+	ptr = lptr;
+	last = lptr;
+	
+	while(last->next != NULL){
+		last = last->next;
+	}
+	
+	if(nptr != last){
+		
+		while(ptr != nptr){
+			prev = ptr;
+			ptr = ptr->next;
+		}
+	
+		if(prev != NULL){
+			prev->next = nptr->next; 	//If any node other than the first node matches ,only then prev has to be taken into account 
+		}
+		last->next = nptr;
+		if(nptr == lptr){
+			lptr = lptr->next; 			//Only if the first node matches lptr will change 
+		}
+		nptr->next = NULL;
+		
+	}
+	return lptr;
+		
+}
+
+int main() {
+	
+	int n;
+	int choice = 0;
+	int data = 0;
+	int cache_size = 0;
+	int min;
+	int rchoice;
+	
+	Nodetype *lptr = NULL,*nptr = NULL,*lfu = NULL;
+		
+	printf("Enter Cache size\n");
+	scanf("%d",&n);
+	if(n == 0){
+		printf("ENTER A POSITIVE CACHE SIZE\n");
+	}
+	else{
+		printf("You have the following choices :\n");
+		printf("1.Access a Data element\n");
+		printf("2.Exit\n");
+		
+		while(choice != 2){
+			
+			printf("Enter choice\n");
+			scanf("%d",&choice);
+			
+			switch(choice){
+				
+				case 1:
+					printf("Enter data element that is to be accessed\n");
+					scanf("%d",&data);
+					
+					
+					
+					if(cache_size < n){
+						
+						
+						nptr = exists(lptr,data); 
+						
+						
+						if(nptr == NULL){
+							lptr = InsertAtEnd(lptr,data);
+						}
+						else{
+							//printf("\n,,%d\n",nptr->data);
+							nptr->freq += 1;
+							lptr = AppendAtEnd(lptr,nptr);
+						}
+						
+					}				
+					else{
+						nptr = exists(lptr,data);
+						
+						if(nptr != NULL){
+							nptr->freq = nptr->freq + 1;
+							lptr = AppendAtEnd(lptr,nptr);
+						}
+						else{
+							printf("Replacement choices:\n");
+							printf("1.LRU:\n");
+							printf("2.MRU:\n");
+							printf("3.LFU:\n");
+							scanf("%d",&rchoice);
+						
+							switch(rchoice){
+								
+								case 1:/*LRU*/
+								
+									printf("ELement removed: %d\n",lptr->data);
+									lptr->data = data;
+									lptr->freq = 1;
+									lptr = AppendAtEnd(lptr,lptr);						
+								
+									break;
+									
+								case 2:/*MRU*/
+									
+									nptr = lptr;
+									while(nptr->next != NULL){
+										nptr = nptr->next;
+									}
+									printf("Element removed: %d\n",nptr->data);
+									nptr->data = data;
+									nptr->freq = 1;
+									
+									break;
+										
+								case 3:/*LFU*/
+									
+									min = INT_MAX;
+									nptr = lptr;
+									lfu = lptr;
+									while(nptr != NULL){
+										if(nptr->freq < min){
+											min = nptr->freq;
+											lfu = nptr;
+										}
+										nptr = nptr->next;
+									}
+									printf("Element removed: %d\n",lfu->data);
+									lfu->data = data;
+									lfu->freq = 1;
+									lptr = AppendAtEnd(lptr,lfu);
+									
+									break;
+										
+								default:
+									
+									printf("Invalid choice\n");
+	
+									break;
+									
+							}
+						}
+					}
+					cache_size = getlength(lptr);
+					
+					
+					break;
+				case 2:
+					printf("*******************EXIT*******************");
+					break;
+				default:
+					printf("Enter a valid choice\n");
+			}
+			
+			
+			
+		}
+		
+	
+	}
+	
+	getch();
+	return 0;
+}