动态存储管理

题目：

阅读教材《计算机操作系统》第四章，掌握存储器管理相关概念和原理。

编写程序模拟实现内存的动态分区法存储管理。内存空闲区使用自由链管理，采用最坏适应算法从自由链中寻找空闲区进行分配，内存回收时假定不做与相邻空闲区的合并。

假定系统的内存共640K，初始状态为操作系统本身占用64K。在t1时间之后，有作业A、B、C、D分别请求8K、16K、64K、124K的内存空间；在t2时间之后，作业C完成；在t3时间之后，作业E请求50K的内存空间；在t4时间之后，作业D完成。要求编程序分别输出t1、t2、t3、t4时刻内存的空闲区的状态。

#include<stdio.h>#include<stdlib.h>typedef struct freelink{int len,address;/*len 为分区长度，address为分区起始地址*/struct freelink *next ;}freelink;typedef struct busylink{char name; /* 作业或进程名*/int len , address;struct busylink *next;}busylink; freelink *free_head=NULL; //自由链队列（带头结点）队首指针 busylink *busy_head=NULL; //占用区队列队（带头结点）首指针 busylink *busy_tail=NULL; //占用区队列队尾指针void start(void); /* 设置系统初始状态*/ void requireMemo(char name, int require); /*模拟内存分配*/void freeMemo(char name); /* 模拟内存回收*/ void printflink(); /* 模拟系统过了time 时间*/void printfbusy();void main(){int n,i,require; char str; n=1;start(); while(n) {system("cls");printf("/n*********************************************");printf("/n** 进程存储演示 **");printf("/n*********************************************");printf("/n** 1.创建进程并存入内存 **");printf("/n** 2.查看内存空闲区大小 **");printf("/n** 3.唤出进程并释放内存 **");printf("/n** 4.查看内存占用区大小 **");printf("/n** 5.退出程序 **");printf("/n*********************************************");printf("/n请选:(1~5)");scanf("%d",&i); switch(i) { case 1: printf("输入进程名称:"); scanf("/n%c",&str); printf(" 内存大小:"); scanf("%d",&require); requireMemo(str,require); break; case 2: printflink(); system("pause"); break; case 3: printf("输入唤醒进程名称:"); scanf("/n%c",&str); freeMemo(str); break; case 4: printfbusy(); system("pause"); break; case 5: printf("Welcome!/n"); exit(0); } }}void start(void){ freelink * p; busylink *q; free_head=(freelink*)malloc(sizeof( freelink)); free_head->next=NULL; // 创建自由链头结点 busy_head=busy_tail=(busylink*)malloc(sizeof( busylink)); busy_head->next=NULL; // 创建占用链头结点 p=( freelink *)malloc(sizeof( freelink)); p->address=64; p->len=640-64; //OS占用了64K p->next=NULL; free_head->next=p; q=(busylink *)malloc(sizeof( busylink)); q->name='S'; /* S表示操作系统占用 */ q->len=64; q->address=0; q->next=NULL; busy_head->next=q; busy_tail=q;}void requireMemo(char name, int require){if(require<=free_head->next->len){ busylink *q; freelink * w,*v,*u; q=(busylink *)malloc(sizeof( busylink)); q->name=name; q->len=require; q->address=free_head->next->address; q->next=NULL; busy_tail->next=q; busy_tail=q; w=free_head->next; free_head->next=w->next; w->len=w->len-require; w->address=w->address+require; if(w->len==require) { free(w); return ; } u=free_head; v=free_head->next; while(v!=NULL&&v->len>=w->len) { u=v; v=v->next; } u->next=w; w->next=v; }else {printf("Can not allocate/n");}}void printflink() /* 模拟系统过了time 时间*/{freelink *w;int i=1;w=free_head->next;while(w){printf("第%d空闲区的起始地址为: %d/n",i,w->address);printf(" 长度为: %d/n",w->len);w=w->next;i++;}}void printfbusy() /* 模拟系统过了time 时间*/{busylink *w;int i=1;w=busy_head->next;while(w){printf("第%d占用区的起始地址为: %d/n",i,w->address);printf(" 长度为: %d/n",w->len);printf(" 名称为: %c/n",w->name);w=w->next;i++;}}/*void freeMemo(char name) {busylink *q1,*q2;freelink *p1,*p2;freelink *u;q1=busy_head;q2=busy_head->next;while(q2){if(q2->name==name)break ;q1=q2;q2=q2->next;}if(q2==NULL){printf("不存在该进程/n");system("pause");return ;}q1->next=q2->next;p2=(freelink *)malloc(sizeof(freelink));p2->address=q2->address;p2->len=q2->len;p2->next=NULL;free(q2);u=free_head;p1=free_head->next;while(p1){if(p1->len>=p2->len){u=p1;p1=p1->next;continue ;}else{u->next=p2;p2->next=p1;return ;}}if(p1==NULL){u->next=p2;return ;}}*/void freeMemo(char name) {busylink *q1,*q2;freelink *p1,*p2,*m1,*m2,*v1,*v2;freelink *u;v1=NULL;v2=NULL;m1=NULL; //标记前驱空闲区间m2=NULL; //标记后继空闲区间q1=busy_head;q2=busy_head->next;while(q2){if(q2->name==name)break ;q1=q2;q2=q2->next;}if(q2==NULL){printf("不存在该进程/n");system("pause");return ;}q1->next=q2->next;p2=(freelink *)malloc(sizeof(freelink));p2->address=q2->address;p2->len=q2->len;p2->next=NULL;free(q2);p1=free_head->next;v1=free_head;while(p1) //找是否有相邻的前驱空闲区间{ if(p1->address+p1->len==p2->address){m1=p1;break;}v1=p1;p1=p1->next;}p1=free_head->next;v2=free_head;while(p1) //找是否有相邻的后继空闲区间{if(p2->address+p2->len==p1->address){m2=p1;break;}v2=p1;p1=p1->next;}if(m1&&m2) //有前后相邻空闲区{m1->len=m1->len+m2->len+p2->len;v1->next=m1->next;v2->next=m2->next;u=free_head;p1=free_head->next;while(p1){if(p1->len>=m1->len){u=p1;p1=p1->next;continue ;}else{u->next=m1;m1->next=p1;return ;}}if(p1==NULL){u->next=m1;return ;}}if(m1&&m2==NULL){v1->next=m1->next;m1->len=m1->len+p2->len;u=free_head;p1=free_head->next;while(p1){if(p1->len>=m1->len){u=p1;p1=p1->next;continue ;}else{u->next=m1;m1->next=p1;return ;}}if(p1==NULL){u->next=m1;return ;}}if(m1==NULL&&m2){v2->next=m2->next;p2->len=m2->len+p2->len;u=free_head;p1=free_head->next;while(p1){if(p1->len>=p2->len){u=p1;p1=p1->next;continue ;}else{u->next=p2;p2->next=p1;return ;}}if(p1==NULL){u->next=p2;return ;}}if(m1==NULL&&m2==NULL){u=free_head;p1=free_head->next;while(p1){if(p1->len>=p2->len){u=p1;p1=p1->next;continue ;}else{u->next=p2;p2->next=p1;return ;}}if(p1==NULL){u->next=p2;return ;}}}