模拟操作系统FIFO置换算法

来源：互联网发布：mac哑光唇釉色号编辑：程序博客网时间：2024/06/04 00:30
1.简介
写的时候数据结构用了链表而不是数组，所以才有了这么麻烦的一个程序，有的地方比较多余
2.源码
//命中率=1-页面失效次数/页地址流长度。/*地址按下述原则生成：①50%的指令是顺序执行的；②25%的指令是均匀分布在(跳转到)前地址部分；③25%的指令是均匀分布在(跳转到)后地址部分；#具体的实施方法是：A.在[0，119]的指令地址之间随机选取一起点M;B.顺序执行一条指令，即执行地址为M+1的指令；C.在前地址[0，M+1]中随机选取一条指令(跳转到)并执行，该指令的地址为M’;D.顺序执行一条指令，其地址为M’+1；E.在后地址[M’+2，119]中随机选取一条指令(跳转到)并执行；F.重复A—E，直到执行150次指令。*/#include <iostream>using namespace std;#include <stdlib.h>#include <time.h>typedef struct PAGE {int page;PAGE* next;}PAGE;class List {public:PAGE* head, *tail, *temp, *table;int m;List() { m = 0;table = new(PAGE);head = table;tail = table;temp = table; }void InitList();int setm(int m);};void List::InitList() {table = new (PAGE);head = table;table->page = -1;temp = table;for (int i = 2;i <= m;i++) {table = new(PAGE);table->page = -1;temp->next = table;temp = table;if (i == m)table->next = NULL;}tail = table;}int List::setm(int m) {List::m = m;return List::m;}class AddrStream {public:int count, pageNum[150], pageN, i, addr;AddrStream() { count = 0;i = 0;addr = 0;pageN = 0;for (i;i<150;i++) pageNum[i] = 0; };void Generate();void outStream();};void AddrStream::Generate() {srand((unsigned)time(NULL));count = 0;i = 0;while (i<150) {if (count == 0){addr = (int)(120 * rand() / (RAND_MAX + 1));addr = (addr + 1) % 120;pageN = (int)addr / 10;}if (count == 1){addr = (int)((addr + 1)*rand() / (RAND_MAX + 1));pageN = (int)addr / 10;}if (count == 2){addr = (addr + 1) % 120;pageN = (int)addr / 10;}if (count == 3){addr = (int)(/*120 - ((120 - (addr + 2))*rand() / (RAND_MAX + 1))*/ rand() % (120 - (addr + 2)) + addr + 2);addr = addr % 120;pageN = (int)addr / 10;}++count;pageNum[i] = pageN;if (count == 4) { count = 0; }i++;}}void AddrStream::outStream() {for (i = 0;i<150;i++) { cout << pageNum[i] << "  "; }cout << endl;}int main() {int False, answer, m, flag;int hit;int a;PAGE* tail, *output, *temp, *table, *t;False = 0;List list;AddrStream address;cout << "请输入用户页面数：";cin >> a;m = list.setm(a);list.InitList();address.Generate();address.outStream();for (int i = 0;i<150;i++){hit = 0;flag = 0;answer = 1;                        //answer置1代表队满tail = list.tail;temp = list.head;t = list.head;table = list.head;output = list.head;while (table != NULL){if (table->page == -1) { answer = 0; }//answer=0代表队未满table = table->next;}if (answer == 0){while (temp != NULL)   // 遍历{if (temp->page == address.pageNum[i]){hit = 1;     //命中则置一}temp = temp->next;}if (hit == 0)    //hit为0则缺页{False++;int flag2 = 0;do {if (t->page == -1){t->page = address.pageNum[i]; flag2 = 1;}t = t->next;} while (flag2 != 1);}}if (answer == 1){while (temp != NULL){if (temp->page == address.pageNum[i]){flag = 1;//flag置1代表有命中，置0代表没有命中}temp = temp->next;}if (flag == 0){False++;   //没有命中则缺页加一while (t != NULL){if(t->next!=NULL)t->page = t->next->page;  //队列每个元素都前移t = t->next;}tail->page = address.pageNum[i];   //插入缺的页}}for (output;output != NULL;output = output->next)cout << output->page << "  ";cout << endl;}double sum = 1.0 - False / 120.0;cout << "FIFO算法的命中率为：" << sum << "  " << endl;return 0;}
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