实验四存储器管理.docx

1、实验四存储器管理实验四 存储器管理1、目的与要求 本实验的目的是让学生熟悉存储器管理的方法，加深对所学各种存储器管理方案的了解；要求采用一些常用的存储器分配算法，设计一个存储器管理模拟系统，模拟内存空间的分配和释放。2、实验内容设计一个存放空闲块的自由链和一个内存作业分配表，存放内存中已经存在的作业。编制一个按照首次适应法分配内存的算法，进行内存分配。同时设计内存的回收以及内存清理（如果要分配的作业块大于任何一个空闲块，但小于总的空闲分区，则需要进行内存的清理，空出大块的空闲分区）的算法。3实验环境PC兼容机Windows、DOS系统、Turbo c 2.0C语言4实验提示一、数据结构1、自由

2、链内存空区采用自由链结构，链首由指针freep指向，链中各空区按地址递增次序排列。初启动时整个用户内存区为一个大空区，每个空区首部设置一个区头（freearea）结构，区头信息包括：Size 空区大小Next 前向指针，指向下一个空区Back 反向指针，指向上一个空区Adderss 本空区首地址2、内存分配表JOBMAT系统设置一个MAT，每个运行的作业都在MAT中占有一个表目，回收分区时清除相应表目，表目信息包括：Name 用户作业名Length 作业区大小Addr 作业区首地址二、算法存储分配算法采用首次适应法，根据指针freep查找自由链，当找到第一块可满足分配请求的空区便分配，当某空区

3、被分配后的剩余空闲空间大于所规定的碎片最小量mini时，则形成一个较小的空区留在自由链中。回收时，根据MAT将制定分区链入自由链，若该分区有前邻或后邻分区，则将他们拼成一个较大的空区。当某个分配请求不能被满足，但此时系统中所有碎片总容量满足分配请求的容量时，系统立即进行内存搬家，消除碎片。即将各作业占用区集中下移到用户内存区的下部（高地址部分），形成一片连续的作业区，而在用户内存区的上部形成一块较大的空闲，然后再进行分配。本系统的主要程序模块包括：分配模块ffallocation，回收模块ffcollection，搬家模块coalesce及命令处理模块menu，menu用以模拟系统的输入，通过

4、键盘命令选择进行分配模块、回收模块、内存查询以及退出的操作。程序运行的流程如下图：5实验运行情况*MENU*You can select one of the following:(1)Require to be allocate. 请分配内存(2)Require to collecte the size. 将分配的内存回收(3)Check the memory. 检查当前的内存情况(4)Quit. 退出*1Enter your job name:JOB1Enter your job length:1000name length(b) addreJOB1 1000 2000The total

5、left is 4000 bytes6实验程序#include #include #include #include #include #include string.h#define TOTALSPACE 5000 /*起始空闲空间大小#define INITADDRESS 2000 /*起始地址#define MINSPACE 100#define MAXJOBCNT 10 /* 内存中作业数量最大值struct JobMat char name10; int address; int length; struct JobMat * next; struct JobMat * back;s

6、truct FreeArea int address; int size; struct FreeArea * next; struct FreeArea * back;struct JobMat *p_JobMat;struct FreeArea *p_FreeArea;int UnusedSpace; /*未分配的空闲空间大小int CurrentJobCnt; /*目前内存中的作业数量int JobSize; /*目前要分配的作业的大小char JobName10;int JobAddress; void initiation() p_FreeArea=(struct FreeArea

7、*)malloc(sizeof(struct FreeArea); p_FreeArea-size=TOTALSPACE; p_FreeArea-address=INITADDRESS; p_FreeArea-next=NULL; p_FreeArea-back=NULL; UnusedSpace=TOTALSPACE; p_JobMat=NULL; CurrentJobCnt=0; JobSize=0; memset(JobName, 0, 10); JobAddress=0;void ffallocation() struct FreeArea * fp; struct JobMat *j

8、p; struct JobMat *jp1; struct JobMat *jp2; JobAddress=-1; if (UnusedSpacesize) next; else CurrentJobCnt=CurrentJobCnt+1; UnusedSpace=UnusedSpace-JobSize; jp2=(struct JobMat *)malloc(sizeof(struct JobMat); strcpy(jp2-name,JobName); jp2-length=JobSize; jp2-address=fp-address; JobAddress=jp2-address; i

9、f (p_JobMat=NULL) jp2-next=NULL; jp2-back=NULL; p_JobMat=jp2; else jp=p_JobMat; while(jp!=NULL)&(jp2-addressaddress) jp1=jp; jp=jp-next; jp2-next=jp; if (jp=NULL) jp2-back=jp1; jp1-next=jp2; else jp2-back=jp-back; if (jp-back!=NULL) jp1-next=jp2; else p_JobMat=jp2; jp-back=jp2; if (fp-size-JobSizene

10、xt!=NULL) fp-next-back=fp-back; if (fp-back!=NULL) fp-back-next=fp-next; else p_FreeArea=fp-next; else fp-size=fp-size-JobSize; fp-address=fp-address+JobSize; /*exit(1);*/ return; void ffcollection() struct FreeArea *fp; struct FreeArea *fp1; struct FreeArea *fp2; struct JobMat *jp; int f; jp=p_JobM

11、at; f=0; while(jp!=NULL) & strcmp(jp-name, JobName) != 0) jp=jp-next; if (jp!=NULL) CurrentJobCnt=CurrentJobCnt-1; UnusedSpace=UnusedSpace+jp-length; if (p_FreeArea=NULL) p_FreeArea=(struct FreeArea *)malloc(sizeof(struct FreeArea); p_FreeArea-address=jp-address; p_FreeArea-size=jp-length; p_FreeAre

12、a-next=NULL; p_FreeArea-back=NULL; else fp=p_FreeArea; while(fp!=NULL)&(fp-addressaddress) fp1=fp; fp=fp-next; if (fp!=NULL) if (fp-next!=NULL)&(fp-next-address=jp-address+jp-length) f=f+1; if (fp-back!=NULL)&(jp-address=fp1-address+fp1-size) f=f+2; else if (jp-address) = (fp1-address+(fp1-size) f=f

13、+2; switch (f) case 0: fp2=(struct FreeArea *)malloc(sizeof(struct FreeArea); fp2-address=jp-address; fp2-size=jp-length; fp2-next=fp; if (fp!=NULL) fp2-back=fp-back; if (fp-back!=NULL) fp1-next=fp2; else p_FreeArea=fp2; fp-back=fp2; else fp2-back=fp1; fp1-next=fp2; break; case 1: fp-size=fp-size+jp

14、-length; fp-address=jp-address; break; case 2: fp1-size=fp1-size+jp-length; break; case 3: fp1-size=fp1-size+jp-length+fp-size; fp1-next=fp-next; if (fp-next!=NULL) fp-next-back=fp2; free (fp); break; if (jp=p_JobMat) p_JobMat=jp-next; if (jp-next!=NULL) jp-next-back=jp-back; if (jp-back!=NULL) jp-b

15、ack-next=jp-next; free(jp); void showyou() struct JobMat *jp; /*clrscr();*/ if (CurrentJobCntname, jp-length,jp-address); jp=jp-next; printf(The total left is %d bytesn,UnusedSpace);void coalesce() struct FreeArea *fp; struct FreeArea *fp1; struct JobMat *jp; int bottom; if (CurrentJobCnt0) jp=p_Job

16、Mat; bottom=TOTALSPACE+INITADDRESS; while (jp!=NULL) jp-address=bottom-jp-length; bottom=bottom-jp-length; jp=jp-next; fp=p_FreeArea; while(fp!=NULL) fp1=fp; fp=fp-next; free(fp1); p_FreeArea=(struct FreeArea *)malloc(sizeof(struct FreeArea); p_FreeArea-size=UnusedSpace; p_FreeArea-address=INITADDRE

17、SS; p_FreeArea-next=NULL; p_FreeArea-back=NULL; void menu() int select; printf(nnn*MENU*n); printf(You can select one of the following:n); printf(1)Require to be allocate.n); printf(2)Require to collecte the size.n); printf(3)Check the memory.n); printf(4)Quit.n); printf(*n); scanf(%d,&select); swit

18、ch(select) case 1: if( CurrentJobCnt=MAXJOBCNT) printf(The job is too many); else printf(Enter your job name:); scanf(%s,JobName); printf(Enter your job length:); scanf(%d,&JobSize); ffallocation(); switch (JobAddress) case -1: printf(the memory is full); break; case 0: coalesce(); ffallocation(); break; default: break; break; case 2: printf(Enter the name of job:); scanf(%s,JobName); ffcollection(); break; case 3: break; case 4: exit(1); break; default: printf(You input a wrong number!n); break; void main() initiation(); while (1) menu(); showyou(); 7.实验结果