Made some minor changes to B7 (page replacement in C++) code.
- Changed variable names - Indentation and stuff - Added description
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@ -1,136 +1,135 @@
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#include<iostream>
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// Assignment-B7 - Page Replacement in C++ (LRU + Optimal)
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// BEGINNING OF CODE
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#include <cmath>
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#include <complex>
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#include <iostream>
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using namespace std;
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int refstring[] = {0, 2, 1, 6, 4, 0, 1, 0, 3, 1, 2, 1};
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int win, hit = 0, miss = 0, res[4], lastUsed[40];
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int refString[] = {0, 2, 1, 6, 4, 0, 1, 0, 3, 1, 2, 1};
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int window = 0, hit = 0, miss = 0, currentPages[4], lastUsed[40];
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int len = sizeof(refString) / sizeof(refString[0]);
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int findLRU() {
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int minIndex = 0;
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for(int i = 1; i < win; i++){
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if(lastUsed[i] < lastUsed[minIndex]){
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minIndex = i;
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int min_index = 0;
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for (int i=1; i<window; i++) {
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if (lastUsed[i] < lastUsed[min_index]) {
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min_index = i;
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}
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}
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return minIndex;
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return min_index;
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}
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void lru(int rf[], int len)
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{
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for(int i = 0; i < win; i++) {
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res[i] = -1;
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void LRU() {
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for (int i=0; i<window; i++) {
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currentPages[i] = -1;
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lastUsed[i] = -1;
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}
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for(int j = 0; j < len; j++) {
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for (int i=0; i<len; i++) {
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bool hitFlag = false;
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for(int k = 0; k < win; k++){
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if (res[k] == rf[j]){
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for (int j=0; j<window; j++) {
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if (currentPages[j] == refString[i]) {
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hit++;
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lastUsed[k] = j;
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hitFlag = true;
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lastUsed[j] = i;
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break;
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}
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}
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if (!hitFlag) {
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if (hitFlag == false) {
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miss++;
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bool emptyFound = false;
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for(int k = 0; k < win; k++){
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if (res[k] == -1){
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res[k] = rf[j];
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lastUsed[k] = j;
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for (int j=0; j<window; j++) {
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if (currentPages[j] == -1) {
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emptyFound = true;
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currentPages[j] = refString[i];
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lastUsed[j] = i;
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break;
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}
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}
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if(!emptyFound){
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int lruIndex = findLRU();
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res[lruIndex] = rf[j];
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lastUsed[lruIndex] = j;
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if (emptyFound == false) {
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int lru_index = findLRU();
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currentPages[lru_index] = refString[i];
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lastUsed[lru_index] = i;
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}
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}
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}
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cout<<"\nNo of hits (LRU): "<<hit;
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cout<<"\nNo of misses (LRU): "<<miss;
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cout<<endl<<"----- LRU ------";
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cout<<endl<<"Number of hits: "<<hit;
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cout<<endl<<"Number of misses: "<<miss;
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}
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int findOptimal(int rf[], int len, int currentIndex)
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{
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int maxIndex = -1, farthest = currentIndex;
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for(int i = 0; i < win; i++){
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int findOptimal(int current_index) {
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int max_index = -1, farthest = current_index;
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for (int i=0; i<window; i++) {
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int j;
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for(j = currentIndex + 1; j < len; j++){
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if(res[i] == rf[j]){
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if(j > farthest){
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for (j=current_index+1; j<len; j++) {
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if (currentPages[i] == refString[j]) {
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if (j > farthest) {
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farthest = j;
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maxIndex = i;
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max_index = i;
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}
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break;
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}
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}
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if(j == len)
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if (j == len) {
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return i;
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}
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return maxIndex;
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}
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return max_index;
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}
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void optimal(int rf[], int len){
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void Optimal() {
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hit = 0;
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miss = 0;
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for(int i = 0; i < win; i++){
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res[i] = -1;
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for (int i=0; i<window; i++) {
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currentPages[i] = -1;
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}
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for(int j = 0; j < len; j++){
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for (int i=0; i<len; i++) {
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bool hitFlag = false;
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for(int k = 0; k < win; k++){
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if (res[k] == rf[j]){
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for (int j=0; j<window; j++) {
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if (currentPages[j] == refString[i]) {
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hit++;
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hitFlag = true;
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break;
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}
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}
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if (!hitFlag){
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if (hitFlag == false) {
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miss++;
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bool emptyFound = false;
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for(int k = 0; k < win; k++){
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if (res[k] == -1){
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res[k] = rf[j];
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for (int j=0; j<window; j++) {
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if (currentPages[j] == -1) {
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emptyFound = true;
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currentPages[j] = refString[i];
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break;
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}
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}
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if(!emptyFound){
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int optimalIndex = findOptimal(rf, len, j);
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res[optimalIndex] = rf[j];
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if (emptyFound == false) {
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int optimal_index = findOptimal(i);
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currentPages[optimal_index] = refString[i];
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}
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}
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}
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cout<<"\nNo of hits (Optimal): "<<hit;
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cout<<"\nNo of misses (Optimal): "<<miss;
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cout<<endl<<"----- OPTIMAL -----";
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cout<<endl<<"Number of hits: "<<hit;
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cout<<endl<<"Number of misses: "<<miss;
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}
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void display()
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{
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cout<<"\nPages in window are: \n";
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for(int i = 0; i < win; i++){
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cout<<res[i]<<"\n";
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void display() {
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cout<<endl<<"Current pages are:\t";
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for (int i=0; i<window; i++) {
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cout<<currentPages[i]<<" ";
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}
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cout<<endl;
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}
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int main()
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{
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cout<<"\nEnter window size: ";
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cin>>win;
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int len = sizeof(refstring)/sizeof(refstring[0]);
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cout<<"\nBy LRU algorithm: ";
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lru(refstring, len);
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int main() {
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cout<<endl<<"Enter window size:\t";
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cin>>window;
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LRU();
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display();
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cout<<"\n\nBy Optimal Algorithm: ";
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optimal(refstring, len);
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Optimal();
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display();
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}
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// END OF CODE
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