分页式存储的页面置换算法

来源：互联网发布：薛冰是怎么死的知乎编辑：程序博客网时间：2024/05/17 10:55
#include"stdio.h"#include"stdlib.h"#include"conio.h"#define N 16#define num 5  /*进程分配物理块数目*/int A[N]={1,2,3,4,5,6,7,8,5,2,3,2,7,8,1,4};  /*页表映像*/typedef struct page    {  int address;           /*页面地址*/  struct page *next;        }page;struct page *head,*run,*rear;void jccreat()   /*进程分配物理块*/{ int i=1; page *p,*q; head=(page *)malloc(sizeof(page)); p=head; for(i=1;i<=num;i++) { q=(page *)malloc(sizeof(page));                p->next=q;  q->address=0; q->next=NULL; p=q; }            rear=p;}int search(int n){  page *p;  int i=0;  p=head;  while(p->next)  {   if(p->next->address==n)   {   printf("Get it at the page %d\n",i+1);   run=p;   return 1;}   p=p->next;   i++;  }   return 0;} void changeOPT(int n,int position){  int i;  int total=0;  int flag=1;  int distance[num];  int MAX;  int order=0;  page *p,*q;  p=head->next;  q=head->next;   for(i=0;i<num;i++)  distance[i]=100;  i=0;  while(p)  {   if(p->address==0)   {flag=0;    break;}   p=p->next;   i++;  }   if(!flag)   {p->address=n;    printf("Change the page %d\n",i+1);   }   else   {    while(q)    {     for(i=position;i<N;i++)     {if(q->address==A[i])     distance[total]=i-position;}     total++;     q=q->next;    }    MAX=distance[0];    for(i=0;i<num;i++)    {     if(distance[i]>MAX)      {        MAX=distance[i];        order=i;       }    }    printf("Change the page %d\n",order+1);    i=0;    while(p)    {     if(i==order)     p->address=n;     i++;     p=p->next;    }   }   } void changeLRU(int n){  int i=0;  int flag=1;  page *p,*delect;  p=head->next;   while(p)  {   if(p->address==0)   {flag=0;    p->address=n;    printf("Change the page %d\n",i+1);    break;}   p=p->next;   i++;  }   if(flag)   {    delect=head->next;    head->next=delect->next;    printf("Delect from the head, and add new to the end.\n");    delect->address=n;    rear->next=delect;    rear=delect;    rear->next=NULL;   }} float OPT(){ int i; int lose=0; float losef; float percent; for(i=0;i<N;i++) {  if(search(A[i])==0)    {    lose++;    changeOPT(A[i],i);  } }   losef=lose;    percent=1-(losef/N);   return percent;} float LRU(){ int i; int lose=0; float losef; float percent; page *p; for(i=0;i<N;i++) {  if(search(A[i])==0)  {    lose++;    changeLRU(A[i]);  }  else    {    p=run->next;    run->next=p->next;    rear->next=p;    rear=p;    rear->next=NULL;    printf("Move it to end of queue.\n");   } }   losef=lose;    percent=1-(losef/N);   return percent;}  main()  /*主函数部分*/{float percent;   int choice;  printf("Select the arithmetic:\n(1)OPT\n(2)LRU\nyour choice is:");  scanf("%d",&choice);/*选择页面置换算法*/  jccreat();               /*创建进程*/  if(choice==1)           /*采用OPT算法置换*/  {percent=OPT();        /*计算OPT时的缺页率*/  printf("The percent of OPT is %f",percent);}  else if(choice==2)      /*采用LRU算法置换*/  {percent=LRU();       /*计算LRU时的缺页率*/  printf("The percent of OPT is %f",percent);}  else printf("Your choice is invalid.");  getch();}
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