osnew.cpp

一个模拟操作系统进程申请释放的简单程序

#include<iostream.h>
#include<stdlib.h>
static address=0;
struct FreeList
{
		//FreeList *h1;
	FreeList *next;
	int Freesize;//空闲区大小
	int isempty;//判断空闲区接点是否为空.1-空,2-满
	int Allocatesize;//分配区大小
	int name;//作业名称
	int start;//起始地址
};
struct ApplyList
{
		//ApplyList *h2;
	int name;//申请作业名称
	int Applysize;//申请作业大小
	int flag;
	ApplyList *next;
};
FreeList *h1;
ApplyList *h2;
ApplyList *np;
//ApplyList *temp;
class M
{
public:
	void setApplyList();
	void setAllocateList(FreeList *,ApplyList *);
	void DeleteProcess(FreeList *);
	void showApplyList(ApplyList *);
	void showAllocateList(FreeList *);
	void showFreeList(FreeList *);
	bool Find(FreeList *,int);
	bool declare(ApplyList *,int);
};
void M::setAllocateList(FreeList *head1,ApplyList *cp)
{
	FreeList *p=head1->next;
	while(p)
	{
		if((p->Freesize>=cp->Applysize)&&(p->isempty==1))
		{
			if(p->next==NULL)
			{
				p->isempty=2;
				p->Allocatesize=cp->Applysize;
				p->name=cp->name;
				p->start=address;  /*静态全局变量address的初值是0*/
				address+=cp->Applysize;
				FreeList *newfree=new FreeList;
				newfree->Freesize=p->Freesize-cp->Applysize;
				newfree->isempty=1;
				newfree->start=address;
				newfree->next=NULL;
				p->next=newfree;
				cp->flag=2;
			}
			else
			{
				p->name=cp->name;
				p->Allocatesize=cp->Applysize;
			    p->isempty=2;
				p->start=address;
				cp->flag=2;
			}
			break;
		}
		else  /*申请区大于空闲区或空闲区结点不为空*/
		{
			p=p->next;
		}
	}
	if(cp->flag==1)
		cout<<"内存暂时不够，作业"<<cp->name<<"内存分配失败!!!"<<endl;
}
void M::setApplyList()//设置申请表
{
	int name,Applysize;
	char op='y';
	while(op=='y')
	{
		
		cout<<"输入申请作业名称和大小:"<<endl;
		cin>>name>>Applysize;
		//if(declare(h2,name))
		//	continue;
		ApplyList *cp;
		cp=new ApplyList;
		cp->name=name;
		cp->Applysize=Applysize;
		cp->flag=1;
		np->next=cp;
		np=cp;
		//np->next=NULL;
		setAllocateList(h1,cp);
		cout<<"是否继续输入作业，y-是，任意键-否:";
		cin>>op;
		
	}
	np->next=NULL;
}
bool M::declare(ApplyList *head,int name)/*判断申请的作业名是否已经存在*/
{
	ApplyList *p=head->next;
	while(p)
	{
		if(p->name==name)
		{
			cout<<"有同名作业存在于申请表中，请重新输入作业名称!";
		return true;
		}
		p=p->next;
	}
	return false;
}

bool M::Find(FreeList *head,int name)//判断要删除的作业是否在分配表中
{
	FreeList *p=head->next;
	while(p)
	{
		if(p->isempty==2&&p->name==name)
			return true;
		p=p->next;
	}
	return false;
}

void M::DeleteProcess(FreeList *head)
{
	FreeList *p=head->next;
	FreeList *front=head;
	FreeList *q;
	char option='y';
	int name;
	while(option=='y')
	{
		cout<<"请从分配表中输入要删除的作业名称:"<<endl;
		cin>>name;
		if(!Find(head,name))//如果想要删除的作业不在分配表中，则重新输入
		{
			cout<<"你要删除的作业不在分配表中，请重新输入!"<<endl;
			continue;
		}
		else
		{
			while(p->name!=name&&p!=NULL)/*往下查找，找到,p为止*/
			{
				front=p;
				p=p->next;
			}
			q=p->next;
			if(q==NULL)//要删除的是最后一个结点
			{
				if(front->isempty==1)
				{
					address-=p->Allocatesize;/*删除后，释放空闲区*/
					front->Freesize+=p->Allocatesize;
					front->next=NULL;
					delete p;
				}
				else
				{
					address-=p->Allocatesize;
					p->Freesize=p->Allocatesize;
					p->isempty=1;
				}
			}
			else if(p==head->next)//要删除的是第一个结点
			{
				if(p->next->isempty==1)/*如果下一段相邻内存是空闲区的话，*/
				{                                      /*则把它与释放掉后的空闲区连起来*/
					address-=p->Allocatesize;
					p->Freesize=p->Allocatesize+p->next->Freesize;
					p->isempty=1;
					p->next=q->next;
					delete q;
				}
				else                   
				{
					address-=p->Allocatesize;
					p->Freesize=p->Allocatesize;
					p->isempty=1;
				}
			}
			else//要删除的是中间结点
			{
				if(front->isempty==1&&q->isempty==2)
				{
					address-=p->Allocatesize;
					front->Freesize+=p->Allocatesize;
					front->next=p->next;
					delete p;
				}
				else if(front->isempty==2&&q->isempty==1)
				{
					address-=p->Allocatesize;
					p->Freesize=p->Allocatesize+q->Freesize;
					p->isempty=1;
					p->next=q->next;
					delete q;
				}
				else if(front->isempty==1&&q->isempty==1)
				{
					address-=p->Allocatesize;
					front->Freesize+=p->Allocatesize+q->Freesize;
					front->next=q->next;
					delete p;
					delete q;
				}
				else
				{
					address-=p->Allocatesize;
					p->Freesize=p->Allocatesize;
					p->isempty=1;
				}
			}
		}
			cout<<"是否继续删除作业，y-是，任意键-否:"<<endl;
			cin>>option;
	}
}
void M::showAllocateList(FreeList *head)//输出分配表的函数
{
	FreeList *p=head->next;
	cout<<"分配的作业名称，大小，地址为:"<<endl;
	while(p)
	{
		if(p->isempty==2)
		{
		cout<<p->name<<"  "<<p->Allocatesize<<"  "<<p->start<<endl;
		}
	    p=p->next;
	}
}
void M::showApplyList(ApplyList *head)//输出申请表
{
    ApplyList *p=head->next;
	cout<<"申请的作业名称和大小:"<<endl;
	while(p!=NULL)
	{
		cout<<p->name<<"\t"<<p->Applysize<<endl;
	p=p->next;
	}
}
void M::showFreeList(FreeList *head)//输出空闲表
{
	FreeList *p=head;//->next;
	cout<<"空闲区起始地址和大小:"<<endl;
	while(p)
	{
		if(p->isempty==1)
		cout<<p->start<<"  "<<p->Freesize<<endl;
		p=p->next;
	}
}
void main()
{
	h1=new FreeList;
	FreeList *f=new FreeList;
	f->Freesize=640;
	f->Allocatesize=0;
	f->isempty=1;
	f->start=0;
	f->next=NULL;
	h1->next=f;
    h2=new ApplyList;
	h2->next=NULL;
	np=h2;
	int choosen;
	M m;
	char c='y';
	while(c=='y')
	{
		cout<<"输入你的选择:1-输入，2-删除，3-退出";
	cin>>choosen;
	switch(choosen)
	{
	case 1:
		m.setApplyList();
		m.showApplyList(h2);
		m.showAllocateList(h1);
		m.showFreeList(h1);
		break;
		   
	case 2:
		    m.DeleteProcess(h1);
			m.showApplyList(h2);
			m.showAllocateList(h1);
			m.showFreeList(h1);
			break;
	case 3:
		exit(1);
	}
	cout<<"是否继续,y-是，任意键-否:";
	cin>>c;
	}
}