os2.cpp

操作系统的内存分配与回收的实验代码

#include <iostream.h>
#include <stdio.h>
#include <malloc.h>
#define free 0;//可用
#define busy 1;//不可用
#define null 0;


struct node{ int name;
             int size;
			 int address_begin;
			 int address_end;
			 int state;
			 };
struct queue{  struct node p;
               struct queue *front;
			   struct queue *rear;
			 };
struct queue *head,*find;
void initial()//初始化一个size1000的空间
{  
   head=(struct queue*)malloc(sizeof(struct node));
   find=head;
   head->p.name=1;
   head->p.size=1000;
   head->p.address_begin=0;
   head->p.address_end=1000;
   head->front=head;
   head->rear=null;
   head->p.state=free;
}

void creat()//创建一个进程并为该进程申请一个空间
{ 
  struct queue *t;
  int n;
  cout<<"please enter the size"<<endl;
  cin>>n;
   t=find;
    while(n<t->p.size)
	{  
	   if(!t)
		 cout<<"分配失败，找不到足够大的空间"<<endl;
	   
	   else if(n>t->p.size) t=t->rear;         // 最佳适应算法
         
	   else
		 { 
		    
			 if((t->p.size-n)>10)
			{   

				//先处理剩余空间然后修改原来的节点的信息即可
               struct queue *k;
				//把剩余的空间化为一个节点并连入队列
			   k=(struct queue*)malloc(sizeof(struct node));
               k->p.size=t->p.size-n;
               k->p.address_begin=t->p.address_begin+n;
               k->p.address_end=t->p.address_end;
			   k->p.state=free;
			   
			   //节点进栈
			     if(t==head)
				 {  find=k;
			        find->front=t;
				    t->rear=find;
				    find->rear=null;
				 }

			      else
				  {
			         struct queue *r;
                     r=find;
				     while((r->p.size<k->p.size)&&(r->rear))
					      r=r->rear;
					 if(r==find)
					 {  find=k;
			            find->front=t;
				        t->rear=find;
				        find->rear=null;
					 }
					 else
					 {
					   r->front=k;
			           k->front=r->front;
			           k->rear=r;
					   r->front->rear=k;
					 }
					 
				  }

               
			 // 修改使用节点的信息
               int name1;
	           cout<<"enter the program's name"<<endl;
	           cin>>name1;
	           t->p.name=name1;
	           t->p.size=n;
               t->p.address_end=t->p.address_begin+n;
               t->p.state=busy;
			   
			   
			 }
			 
		    else
			{   
			   //如果剩余空间过小就不再划分，直接修改节点信息
	           int name1;
	           cout<<"enter the program's name"<<endl;
	           cin>>name1;
	           t->p.name=name1;
	           t->p.size=n;
               t->p.state=busy;

			 }
		 }
	}
}
//-------------------------------------------
void exit(int e)//结束一个进程并释放它发空间
{ struct queue *t,*p1,*p2;
  t=head;
  while(t->p.name!=e)
	  t=t->rear;
  if(!t) cout<<"找不到该进程"<<endl;
  else 
  {   
	 
	 
	 p1=t->front;//要释放的节点的前一个节点
     p2=t->rear;//要释放的节点的后一个节点
	
	 if((p1->p.state==0)&&(p2->p.state==0))//要释放的节点的前后节点都free
         { 
	       p1->p.size=t->p.size+p2->p.size+p1->p.size;
           p1->rear=p2->rear;
           p2->rear->front=p1;
	       p1->p.address_end=p2->p.address_end;
         }
       else if(p1->p.state==0)//要释放的节点的前节点free
             { 
	           p1->p.size=t->p.size+p1->p.size;
               p1->rear=p2;
               p2->front=p1;
               p1->p.address_end=p2->p.address_end;

	          }
	        else if(p2->p.state==0)//要释放的节点的后节点free
			    {    
				     t->p.state=free;
                     t->p.size=t->p.size+p2->p.size;
                     t->rear=p2->rear;
					if(p2->rear)
                    p2->rear->front=t;
					t->p.address_end=p2->p.address_end;
			     }
		
			
			else   t->p.state=free;//一般情况，直接修改state状态即可
			

  }
}

//-------------------------------------------
void show() //显示内存的使用情况
{ 
   struct queue *r;
   r=head;
   cout<<"show the information"<<endl;
   while(r)
   { 
	    cout<<"the name is  "<<r->p.name<<endl;
        cout<<"the size is  "<<r->p.size<<endl;
		cout<<"the address is from  "<<r->p.address_begin;
		cout<<"  to  "<<r->p.address_end<<endl;
		cout<<"the state is  "<<r->p.state<<endl;
		r=r->rear;
		cout<<"-------------------------------"<<endl;
   }
}

//-------------------------------------------
void main()
{ 
  int i=1;
  initial();
  char s;
  while(i)
  { 
	cout<<"************************************"<<endl;
	cout<<"creat a program please enter c "<<endl;
    cout<<"stop a progam please enter e "<<endl;
	cout<<"show the queue information enter s"<<endl;
    cout<<"************************************"<<endl;
	cin>>s;
    switch(s)
	{  
	   case 'c':  creat();break;
       case 'e': int name0;
		         cout<<"输进你要结束的进程的名字"<<endl;
		         cin>>name0;
		         exit(name0);
				 break;
       case 's': show();
       default: break;
	}

  }
}