LRU算法

//LRU algorithm
//author:chillyCreator
//in the page_information, the bigger number means the newer page.
//if the number in the page_information is -1, it means no page is in this position.
#include<iostream>
using namespace std;

bool isNotIn(int p_page_num);
bool isNotFull(int& position);
void insert(int p_page_num,int position);
int delOldPage();

const int MAX_INT = 32767;
int process_num;//the total number of process pages
int page_size;//the total number of pages
int page_num=0;//the number of page which in the page array
int miss=0;//
int* page_information;//the page information array
int* page;//the page array
int old=0;//how old is a page?

int main()
{
cout << "how many pages of processes ?"<<endl;
cin >> process_num ;
cout << "how many pages in the memory?"<<endl;
cin >> page_size;
page_information = new int[page_size];
page = new int[page_size];
int i;
for(i=0; i<page_size; i++)
{
page[i] = -1;
page_information[i] = -1;
}
int user_test;
cout << "input 1 is user test, 2 is auto test"<<endl;
cin >> user_test;
switch(user_test)
{
case 1:
for(i=0; i < process_num; i++)
{
int process_page_num;
cin >> process_page_num;
cout <<"input process page num is :" <<process_page_num<<endl;
if(isNotIn(process_page_num))
{
miss++;
int temp_position;
if(isNotFull(temp_position))
{
insert(process_page_num,temp_position);
page_num++;
}
else
{
temp_position = delOldPage();
insert(process_page_num,temp_position);
}
}
}
break;
default:
for(i=0; i < process_num; i++)
{
int process_page_num = rand();
cout << process_page_num<<endl;
if(isNotIn(process_page_num))
{
miss++;
int temp_position;
if(isNotFull(temp_position))
{
insert(process_page_num,temp_position);
page_num++;
}
else
{
temp_position = delOldPage();
insert(process_page_num,temp_position);
}
}
}
break;
}
cout <<"miss is " <<miss << "/t the total process num is "<<process_num<<endl;
cout << endl;
cout <<"the miss percentage is miss/process_num = "<<double(miss)/process_num<<endl;
return 0;
}
//the process page is in the page array?;
bool isNotIn(int p_page_num)
{
for(int i=0; i<page_size; i++)
{
if(page[i]==p_page_num)
return false;
}
return true;
}
//the page array is full or not.
//and return the empty position
bool isNotFull(int& position)
{
if(page_size <= page_num)
return false;
int i;
for(i=0; i<page_size; i++)
{
if(page_information[i]==-1)
break;
}
position = i;
return true;
}
//insert a process page to the page in an empty position.
//and the function protect the primite: old from flowover error.
void insert(int p_page_num,int position)
{
old++;
if(old==MAX_INT)
{
old = 1;
for(int i=0; i<page_size; i++)
{
if(page_information[i]!=-1)
page_information[i] = old;
}
}
old++;
page[position] = p_page_num;
page_information[position] = old;
}
int delOldPage()
{
int i;
int min=page_information[0],min_i=0;
for(i=1; i<page_size; i++)
{
if(min > page_information[i])
{
min = page_information[i];
min_i = i;
}
}
return min_i;
}