操作系统-存储管理动态分区分配及回收算法附源码.doc

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存储管理动态分区分配及回收算法

课程名称：计算机操作系统班级：信1501-2
实验者XX：琛实验日期：2021年5月20日
评分：教师签名：
一、实验目的
分区管理是应用较广泛的一种存储管理技术。本实验要求用一种构造化高级语言构造分区描述器，编制动态分区分配算法和回收算法模拟程序，并讨论不同分配算法的特点。
二、实验要求
1、编写：First Fit Algorithm
2、编写：Best Fit Algorithm
3、编写：空闲区回收算法
三、实验过程
〔一〕主程序
1、定义分区描述器 node，包括 3 个元素：
〔1〕adr——分区首地址
〔2〕size——分区大小
〔3〕next——指向下一个分区的指针
2、定义 3 个指向 node 构造的指针变量：
〔1〕head1——空闲区队列首指针
〔2〕back1——指向释放区 node 构造的指针
〔3〕assign——指向申请的存分区 node 构造的指针
3、定义 1 个整形变量：
free——用户申请存储区的大小〔由用户键入〕
〔二〕过程
1、定义 check 过程，用于检查指定的释放块〔由用户键入〕的合法性
2、定义 assignment1 过程，实现 First Fit Algorithm
3、定义 assignment2 过程，实现 Best Fit Algorithm
4、定义 acceptment1 过程，实现 First Fit Algorithm 的回收算法
5、定义 acceptment2 过程，实现 Best Fit Algorithm 的回收算法
6、定义 print 过程，打印空闲区队列
〔三〕执行
程序首先申请一整块空闲区，其首址为 0，大小为 32767；然后，提示用户使用哪种分
配算法，再提示是分配还是回收；分配时要求输入申请区的大小，回收时要求输入释放区的
首址和大小。
实验代码
Main.cpp
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<iostream>
usingnamespace std;
#defineMAX_SIZE 32767
typedefstructnode
{
int id;
int adr;
int size;
structnode *next;
}Node;
Node *head1, *head2, *back1, *back2, *assign;
int request;
int check(intadd, intsiz, charc)
{
Node *p, *head;
int check = 1;
if (add<0 || siz<0)
check = 0;/*地址和大小不能为负*/
if (c == 'f' || c == 'F')
head = head1;
else
head = head2;
p = head->next;
while ((p != NULL) && check)
if (((add<p->adr) && (add + siz>p->adr)) || ((add >= p->adr) && (add<p->adr + p->size)))
check = 0;
else
p = p->next;
if(check == 0)
printf("\t输入释放区地址或大小有错误！！！\n");
return check;
}
void init()
{
Node *p;
head1 = (Node*)malloc(sizeof(Node));
head2 = (Node*)malloc(sizeof(Node));
p = (Node*)malloc(sizeof(Node));
head1->next = p;
head2->next = p;
p->size = MAX_SIZE;
p->adr = 0;
p->next = NULL;
p->id = 0;
}
Node* assignment1(intnum, intreq)
{
Node *before, *after, *ass;
ass = (Node*)malloc(sizeof(Node));
before = head1;
after = head1->next;
ass->id = num;
ass->size = req;
while (after->size<req)
{
before = before->next;
after = after->next;
}
if (after == NULL)
{
ass->adr = -1;
}
else
{
if (after->size == req)
{
before->next = after->next;
ass->adr = after->adr;
}
else
{
after->size -= req;
ass->adr = after->adr;
after->adr += req;
}
}
return ass;
}
void acceptment1(intaddress, intsiz, intrd)
{
Node *before, *after;
int insert = 0;
back1 = (Node*)malloc(sizeof(Node));
before = head1;
after = head1->next;
back1->adr = address;
back1->size = siz;
back1->id = rd;
back1->next = NULL;
while (!insert&&after)
{//将要被回收的分区插入空闲区〔按首址大小从小到大插入〕
if ((after == NULL) || ((back1->adr <= after->adr) && (back1->adr >= before->adr)))
{
before->next = back1;
back1->next = after;
insert = 1;
}
else
{
before = before->next;
after = after->next;
}
}
if (insert)
{
if (back1->adr == before->adr + before->size)
{//和前边分区合并
before->size += back1->size;
before->next = back1->next;
free(back1);
}
elseif (after&&back1->adr + back1->size == after->adr)
{//和后边分区合并
back1->size += after->size;
back1->next = after->next;
back1->id = after->id;
free(after);
after = back1;
}
printf("\t首先分配算法回收存成功！\n");
}
else
printf("\t首先分配算法回收存失败！\n");
}
Node* assignment2(intnum, intreq)
{
Node *before, *after, *ass, *q;
ass = (Node*)malloc(sizeof(Node));
q = (Node*)malloc(sizeof(Node));
before = head2;
after = head2->next;
ass->id = num;
ass->size = req;
while (after->size<req)
{
before = before->next;
after = after->next;
}
if (after == NULL)
{
ass->adr = -1;
}
else
{
if (after->size == req)
{
before->next = after->next;
ass->adr = after->adr;
}
else
{
q = after;
before->next = after->next;
ass->adr = q->adr;
q->size -= req;
q->adr += req;
before = head2;
after = head2->next;
if (after == NULL)
{
before->next = q;
q->next = NULL;
}
else
{
while ((after->size)<(q->size))
{
before = before->next;
after = after->next;
}
before->next = q;
q->next = after;
}
}
}
return (ass);
}
void acceptment2(intaddress, intsiz, intrd)
{
Node *before, *after;
int insert = 0;
back2 = (Node*)malloc(sizeof(Node));
before = head2;
after = head2->next;
back2->adr = address;
back2->size = siz;
back2->id = rd;
back2->next = NULL;
if (head2->next == NULL)
{//空闲队列为空
head2->next = back2;
head2->size = back2->size;
}
else
{//空闲队列不为空
while (after)
{
if (back2->adr == after->adr + after->size)
{//和前边空闲分区合并
before->next = after->next;
after->size += back2->size;
back2 = after;
}
else
{
before = before->next;
after = after->next;
}

}
before = head2;
after = head2->next;
while (after)
{
if (after->adr == back2->adr + back2->size)
{//和后边空闲区合并
before->next = after->next;
back2->size += after->size;
}
else
{
before = before->next;
after = after->next;
}
}
before = head2;
after = head2->next;
while (!insert)
{//将被回收的块插入到恰当的位置〔按分区大小从小到大〕
if (after == NULL || ((after->size>back2->size) && (before->size<back2->size)))
{
before->next = back2;
back2->next = after;
insert = 1;
break;
}
else
{
before = before->next;
after = after->next;
}
}
}
if (insert)
printf("\t最正确适应算法回收存成功！\n");
else
printf("\t最正确适应算法回收存失败！！\n");
}

void print(charchoice)//输出空闲区队列信息
{
Node *p;
if (choice == 'f' || choice == 'F')
p = head1->next;
else
p = head2->next;
if (p)
{
printf("\n空闲区队列的情况为：\n");
printf("\t编号\t首址\t终址\t大小\n");
while (p)
{
printf("\t%d\t%d\t%d\t%d\n", p->id, p->adr, p->adr + p->size - 1, p->size);
p = p->next;
}
}
}

void menu()//菜单及主要过程
{
char chose;
int ch, num=0, r, add, rd;
while (1)
{
system("cls");
printf("-------存储管理动态分区分配及回收算法-------\n");
printf(" F 最先适应算法\n");
printf(" B 最正确适应算法\n");
printf(" E 退出程序\n");
printf("----------------------------------------------\n");
printf("请选择算法:");
cin >> chose;
//scanf("%c", &chose);

if (chose == 'e' || chose == 'E')
exit(0);
else
{
system("cls");
while (1)
{
if (chose == 'f' || chose == 'F')
printf("最先适应算法:\n");
if (chose == 'b' || chose == 'B')
printf("最正确适应算法:\n");
printf("----------------------------------------------\n");
printf(" 1 分配存\n");
printf(" 2 回收存\n");
printf(" 3 查看存\n");
printf(" 4 返回\n");
printf("----------------------------------------------\n\n");
printf("请选择:");
scanf("%d", &ch);
fflush(stdin);
switch (ch)
{
case 1:
printf("输入申请的分区大小："); scanf("%d", &r);
if (chose == 'f' || chose == 'F')
assign = assignment1(num, r);
else
assign = assignment2(num, r);
if (assign->adr == -1)
{
printf("分配存失败！\n");
}
else
printf("分配成功！分配的存的首址为:%d\n", assign->adr);
break;
case 2:
printf("输入释放的存的首址："); scanf("%d", &add);
printf("输入释放的存的大小："); scanf("%d", &r);
printf("输入释放的存的编号："); scanf("%d", &rd);
if (check(add, r, chose))
{
if (chose == 'f' || chose == 'F')
acceptment1(add, r, rd);
else
acceptment2(add, r, rd);
}
break;
case 3:print(chose); break;
case 4:menu(); break;
}
}
}
}
}
void main()//主函数
{
init();
menu();
}

四、实验结果

五、实验总结

通过这次实验我练习了存储管理动态分区分配及回收算法，对操作系统中动态可变分区存储管理有了更深刻的了解。刚开场编程时并没有什么思路，查阅相关书籍，浏览网上的论坛后，才对这次实验有了编程思路，在编程中总会遇到各种意想不到问题，这些问题一定要解决。在解决问题的同时，自己的编程能力也在提高。

. .word.zl.