操作系统内存分配与回收

#include<stdio.h>
#include<malloc.h>
#include<conio.h>
typedef struct area{//区
int startaddress;
int size;
int state; //0表示闲置,1表示已分配
struct area *next;
}block;
typedef struct job{//作业
int startaddress;
char name[20];
struct job *next;
}job;
block *head1;//空闲区头指针
block *current;//每次寻找合适空闲区的起始地址
job *head2;
void outputblock()//输出内存状态
{
block *p=head1;
printf("============================================================= ===============\n");
printf("当前分区说明表(0表示闲置,1表示已分配):\n");
printf("起始地址长度状态\n");
printf(" %d %d %d\n",p->startaddress,p->size,p->state);
p=p->next;
while(p!=head1)
{
printf(" %d %d %d\n",p->startaddress,p->size,p->state);
p=p->next;
}
printf("============================================================= ===============\n");
}
block * search(int m)
{
block *p;
p=current;
if(p->state==0&&p->size>=m)
{
return p;
}
p=p->next;
while(p!=current)
{
if(p->state==0&&p->size>=m)
{
return p;
}
p=p->next;
}
return NULL;
}
int searchjobname(char s[20]){//找作业并删除
job *tempjob;
job *tempjob1;
int address;
tempjob=head2->next;
tempjob1=head2;
while(tempjob!=NULL){
if(*tempjob->name==*s){
address=tempjob->startaddress;
tempjob1->next=tempjob->next;
free(tempjob);
return address;
}
tempjob1=tempjob;
tempjob=tempjob->next;
}
return -1;
}
void deleteblock(int address){//回收地址为address的分配区block * tempblock=head1;
block * aimblock=head1;
block *p;
block *q;
while(aimblock->startaddress!=address){aimblock=aimblock->next;} while(tempblock->next!=aimblock){tempblock=tempblock->next;} q=tempblock->next;
p=q;
if(aimblock!=head1&&tempblock->state==0){
tempblock->size=tempblock->size+aimblock->size;
tempblock->next=p->next;
free(aimblock);
aimblock=tempblock;
tempblock=tempblock->next;
}
else{aimblock->state=0;}
q=aimblock->next;
p=q;
if(q!=head1&&q->state==0){
aimblock->size=aimblock->size+q->size;
aimblock->next=p->next;
free(q);
aimblock->state=0;
}
else{aimblock->state=0;}
}
void main()
{
int applyarea;
int chioc;
char jobname[20];
int address;
job *tempjob;
block *tempblock;
block *h;
head1=new block;
head1->startaddress=0;
head1->size=1000;
head1->state=0;
head1->next=head1;
head2=new job;//作业链表的头结点
head2->next=NULL;
outputblock();
while(1)
{ if(head1==head1->next){current=head1;} printf("申请主存空间按“1”,");
printf("回收主存空间按“2”");
printf("请选择:");
scanf("%d",&chioc);
if(chioc==1)
{
printf("请输入要申请的内存大小：");
scanf("%d",&applyarea);
h=search(applyarea);
if(h!=NULL)
{ if(h->size==applyarea){
h->state=1;
address=h->startaddress;
current=h->next;
}
else{
tempblock=new block;//新的空闲块
tempblock->size=h->size-applyarea;
tempblock->startaddress=h->startaddress+applyarea;
tempblock->state=0;
h->size=applyarea;
h->state=1;
address=h->startaddress;
tempblock->next=h->next;
h->next=tempblock;
current=tempblock;
}
tempjob=new job;
printf("请输入作业名：");
scanf("%s",tempjob->name);
tempjob->startaddress=address;
tempjob->next=head2->next;
head2->next=tempjob;
outputblock();
}
else{printf("无法满足请求!\n");printf("-------------------\n");}
}
if(chioc==2)
{
printf("请输入要回收的作业的作业名：");
scanf("%s",jobname);
address=searchjobname(jobname);
if(address>=0){
deleteblock(address);
outputblock();
}
else{printf("该作业不存在!");}
}
} }。