shijianpian.cpp

操作系统课程设计之时间片轮转算法

#include"stdio.h"
#include"iostream.h"
struct  pcb
{
	char  *name;
	int   time;
	int   T; 
	char  state;
	struct  pcb  *next;
};
pcb * in()
{
	pcb *head,*s,*r;
	for(int i=0;i<5;i++)
	{
		s=(pcb *)new(pcb);
		cout<<"进程P"<<i+1<<"运行时间:";
    	cin>>s->time;
		s->next=NULL; 
		s->T=0;s->state='R';
		switch(i)
		{
		case 0: 		s->name="p1"; break;
		case 1: 		s->name="p2"; break;
		case 2: 		s->name="p3"; break;
		case 3: 		s->name="p4"; break;
		case 4: 		s->name="p5"; break;
		}
		if(i==0)
		{   head=s;r=s;  }
		else
		{
			r->next=s; 
			if (i==4) s->next=head;
			r=s;
		}
	}
	return head;
}

void dis(pcb *h,int m)
{
	pcb *s,*r;
	r=h;	cout<<endl<<"进程对列为: ";
	if(m==0) cout<<"空"<<endl; 
	else
	{
		for(int i=0;i<5;i++)
		{
			if((r!=NULL)&&(r->state!='E'))  cout<<r->name<<"  ";
			r=r->next;
		}
		cout<<endl;
		r=h;	cout<<endl<<"             进程信息"<<endl;
		cout<<" 进程名 要求运行 已运行 状态 指针"<<endl;
		for( i=0;i<5;i++)
		{
			if((r!=NULL)&&(r->state!='E'))
			{
				cout<<"   "<<r->name<<"      "<<r->time<<"       "<<r->T<<"     "<<r->state;
				s=r->next; 
				for(int i=0;i<5;i++)
				{
					if((s->state!='E'))
					{
						cout<<"    "<<s->name<<endl; break;
					}
					s=s->next;
				}
			}
			r=r->next;
		}
	}
}
void run(pcb *h)
{
	for(int i=0;i<5;i++)
	{
		if(h->state!='E')
		{
			h->T=h->T+1;
			cout<<h->name<<"  ";
			if(h->time==h->T)   h->state='E';
		}
		h=h->next;
	}
	cout<<endl;
}
void main()
{
	pcb *head,*s;int j=1,m=1;
	head=in(); 

	dis(head,m);
	while(m!=0)
	{   
		cout<<"------------------------------------"<<endl;
		cout<<"第"<<j<<"次执行：";
		run(head);s=head;m=5;
		for(int i=0;i<5;i++)
		{
			if(s->state=='E')  m--;
			s=s->next;
		}
		dis(head,m);
		j++;
	}
    cout<<endl<<"*****调度结束*****"<<endl;
}