Random.cpp

// FILE: Random.cpp
// A Bautista, B Franco, E Mora
// OS, Fall 2023, Transy U
//
// Implementation for Random that contains all functions needed to page a process using the Random algorithm
//

#include "Random.h"
#include "Table.h"
#include <iostream>

using namespace std;

Random::Random(){
  pageFaults = 0;
  srand(time(NULL));
}

Random::~Random(){}

int Random::randomPager(queue<int>& addresses,Table& table){
	int freeFrame, address, victimPage, victimFrame, page; 
	int iteration = 0;
	while(!addresses.empty()){
	  //print out page table before manipulation 
	  cout << "iteration: " << iteration++ << endl;
	  table.print();

	  //push all addresses to its specific page
	  address = addresses.front();
	  addresses.pop();
	  page = table.addressPage(address);
	  
	  //if valid bit is not set increase page faults and find a free frame
	  if(!table.valid(page)){
	    pageFaults++;
	    freeFrame = table.freeFrame();

	    //if we have a free frame put page there
	    if(freeFrame != -1){
	      cout << "\t\tfreeFrame: " << freeFrame << endl;
	      table.load(page,freeFrame);
	      table.setValid(page);
	    }
	    
	    // page replacement must be conducted
	    //victim is selected and removed randomly
	    else{
	      victimPage = selectVictim(table);
	      table.setInvalid(victimPage);
	      cout << "\t\tvictimPage: " << victimPage << endl;
	      
	      table.load(page,table.getFrame(victimPage));
	      table.setValid(page);
	    }
	  }
	  cout << "pageFaults: " << pageFaults << endl << endl;
	}
	return pageFaults;
}

int Random::selectVictim(Table& table){
  return table.findPage(rand()%table.totalFrames());
}