用C++模拟操作系统进程调度的几种算法

        ***************************************
    *****1.******* 先来先服务算法 ***********
    *****2.********  时间片轮转   ************
    *****3.********  短作业优先   ************
    *****4.********  优先级调度   ************
    *****5.********  最短剩余时间 ***********

      *****0.**********退出*******************

具体算法的细节想必读者可以从很多地方了解到，下面给出简单的实现代码：

#include<iostream>
using namespace std;

#define MAX_PEOC_ID  65536
#define TIME_SLICE    2

//进程控制块
typedef struct PCB
{
	char name[10];//进程名 id
	char state;  //进程状态 W/R
	int ArriveTime; //进程到达时间
	int StartTime;  //进程开始时间
	int FinshTime;//进程结束时间
	int ServiceTime;//进程服务时间
	float WholeTime; //周转时间
    float Weight_WholeTime;//带权周转时间
	double Average_WholeTime;//平均周转时间
	double Average_Weight_WholeTime;//带权平均周转时间

     int RunTime;//已经占用CPU时间
	 int NeedTime;//还要占用CPU时间
       
	 int Prio;//优先级

	struct PCB *next;
}pcb;


double Sum_WholeTime=0,Sum_Weight_WholeTime=0;
int time=0;
int Proc_Num=0;
pcb *head = NULL;
pcb *tail=NULL;

void FCFS_RunProccess(pcb *proc)
{
	proc->StartTime=time;
	cout<<"时刻 "<<time<<" 开始执行当前作业  "<<proc->name<<endl;
	time+=proc->ServiceTime;
	proc->state='R';
	proc->FinshTime=time;
	proc->WholeTime=proc->FinshTime-proc->ArriveTime;
	proc->Weight_WholeTime=proc->WholeTime/proc->ServiceTime;
    
	Sum_WholeTime+=proc->WholeTime;
	Sum_Weight_WholeTime+=proc->Weight_WholeTime;

	proc->Average_WholeTime=Sum_WholeTime/Proc_Num;
	proc->Average_Weight_WholeTime=Sum_Weight_WholeTime/Proc_Num;
	printf("  到达时间  开始时间  服务时间  完成时间  周转时间  带权周转时间\n");
    printf("%6d    %6d    %6d    %6d    %8.1f    %8.2f\n",
		proc->ArriveTime,proc->StartTime,proc->ServiceTime,
		proc->FinshTime,proc->WholeTime,proc->Weight_WholeTime);
    
	//printf("共 %d 个进程\n",Proc_Num);
	printf("  平均周转时间  平均带权周转时间  \n");
	printf("  %10.2f        %10.2f\n",proc->Average_WholeTime,
		proc->Average_Weight_WholeTime);

}

void FCFS()
{
     pcb* cur_proc=head;
	 pcb*new_proc=NULL;
    while(cur_proc)
	{
        if(cur_proc->state == 'W')
		{
			new_proc=cur_proc;
			FCFS_RunProccess(new_proc);
		}
        cur_proc=cur_proc->next;
		head=cur_proc;
		free (new_proc);
		new_proc=NULL;
	 }
}

void FCFS_CreateProccess()
{
	cout<<"请输入进程的个数: ";
	cin>>Proc_Num;
	if(Proc_Num > MAX_PEOC_ID)
	{
		cout<<"sorry  I can't give you PCB \n";
		return;
	}
	for(int i=1;i<=Proc_Num;++i)
	{
	pcb*new_proc=NULL;
	if((new_proc=(pcb*)malloc(sizeof(pcb))) == NULL)
		{
			perror("malloc");
			return;
		}
		cout<<"请输入第"<<i<<"个进程名： ";
		cin>>new_proc->name;
        cout<<"请输入第"<<i<<"个进程到达时间： ";
		cin>>new_proc->ArriveTime;
		cout<<"请输入第"<<i<<"个进程服务时间：";
		cin>>new_proc->ServiceTime;
	    new_proc->next=NULL;
		if(head == NULL)
		{
		    new_proc->next=head;
			head=new_proc;
			tail=head;
			time=new_proc->ArriveTime;
		
		}
		else
		{
			if(head->ArriveTime>new_proc->ArriveTime)
			{
				new_proc->next=head;
				head=new_proc;
			}
			else
			{
			pcb* cur_proc=head;
            while(cur_proc->next != NULL && cur_proc->next->ArriveTime<new_proc->ArriveTime)
			{
				cur_proc=cur_proc->next;
			}
			if(cur_proc->next==NULL)
			{
				tail=new_proc;
			}
			new_proc->next=cur_proc->next;
			cur_proc->next=new_proc;
			
			}
		if(new_proc->ArriveTime < time)
			{
				time=new_proc->ArriveTime;
			}
		}
			new_proc->StartTime=0;
			new_proc->FinshTime=0;
			new_proc->WholeTime=0;
			new_proc->Weight_WholeTime=0;
			new_proc->Average_Weight_WholeTime=0;
			new_proc->Average_WholeTime=0;
			new_proc->state= 'W';
			new_proc->RunTime=0;
			new_proc->NeedTime=0;
	}
}

void ShortJobsCreateProccess()
{
	cout<<"请输入进程的个数: ";
	cin>>Proc_Num;
	if(Proc_Num > MAX_PEOC_ID)
	{
		cout<<"sorry  I can't give you PCB \n";
		return;
	}
	for(int i=1;i<=Proc_Num;++i)
	{
		pcb*new_proc=NULL;
		if((new_proc=(pcb*)malloc(sizeof(pcb))) == NULL)
		{
			perror("malloc");
			return;
		}
		cout<<"请输入第"<<i<<"个进程名： ";
		cin>>new_proc->name;
        cout<<"请输入第"<<i<<"个进程到达时间： ";
		cin>>new_proc->ArriveTime;
		cout<<"请输入第"<<i<<"个进程服务时间：";
		cin>>new_proc->ServiceTime;
		new_proc->next=NULL;
		if(head == NULL)
		{
			new_proc->next=head;
			head=new_proc;
			tail=head;
			time=new_proc->ArriveTime;
			
		}
		else
		{
			if(head->ServiceTime>new_proc->ServiceTime)
			{
				new_proc->next=head;
				head=new_proc;
			}
			else
			{
				pcb* cur_proc=head;
				while(cur_proc->next != NULL && cur_proc->next->ServiceTime<new_proc->ServiceTime)
				{
					cur_proc=cur_proc->next;
				}
				if(cur_proc->next==NULL)
				{
					tail=new_proc;
				}
				new_proc->next=cur_proc->next;
				cur_proc->next=new_proc;
				
			}
			if(new_proc->ArriveTime < time)
			{
				time=new_proc->ArriveTime;
			}
		}
		new_proc->StartTime=0;
		new_proc->FinshTime=0;
		new_proc->WholeTime=0;
		new_proc->Weight_WholeTime=0;
		new_proc->Average_Weight_WholeTime=0;
		new_proc->Average_WholeTime=0;
		new_proc->state= 'W';
		new_proc->RunTime=0;
		new_proc->NeedTime=0;
	}
}

void PrioCreateProccess()
{
	cout<<"请输入进程的个数: ";
	cin>>Proc_Num;
	if(Proc_Num > MAX_PEOC_ID)
	{
		cout<<"sorry  I can't give you PCB \n";
		return;
	}
	for(int i=1;i<=Proc_Num;++i)
	{
		pcb*new_proc=NULL;
		if((new_proc=(pcb*)malloc(sizeof(pcb))) == NULL)
		{
			perror("malloc");
			return;
		}
		cout<<"请输入第"<<i<<"个进程名： ";
		cin>>new_proc->name;
        cout<<"请输入第"<<i<<"个进程到达时间： ";
		cin>>new_proc->ArriveTime;
		cout<<"请输入第"<<i<<"个进程服务时间：";
		cin>>new_proc->ServiceTime;
		cout<<"请输入第"<<i<<"个进程优先级:(值越小优先级越高) ";
		cin>>new_proc->Prio;
		new_proc->next=NULL;
		if(head == NULL)
		{
			new_proc->next=head;
			head=new_proc;
			tail=head;
			time=new_proc->ArriveTime;
			
		}
		else
		{
			if(head->Prio>new_proc->Prio)
			{
				new_proc->next=head;
				head=new_proc;
			}
			else
			{
				pcb* cur_proc=head;
				while(cur_proc->next != NULL && cur_proc->next->Prio<new_proc->Prio)
				{
					cur_proc=cur_proc->next;
				}
				if(cur_proc->next==NULL)
				{
					tail=new_proc;
				}
				new_proc->next=cur_proc->next;
				cur_proc->next=new_proc;
				
			}
			if(new_proc->ArriveTime < time)
			{
				time=new_proc->ArriveTime;
			}
		}
		new_proc->StartTime=0;
		new_proc->FinshTime=0;
		new_proc->WholeTime=0;
		new_proc->Weight_WholeTime=0;
		new_proc->Average_Weight_WholeTime=0;
		new_proc->Average_WholeTime=0;
		new_proc->state= 'W';
		new_proc->RunTime=0;
		new_proc->NeedTime=0;
	}
}
void  RR_RunProccess(PCB *proc)
{
	proc->StartTime=time;
	cout<<"时刻 "<<time<<" 开始执行当前作业  "<<proc->name<<endl;
    proc->RunTime+=TIME_SLICE;
	time+=TIME_SLICE;
	proc->NeedTime=proc->ServiceTime-proc->RunTime;
	if(proc->NeedTime <=0)
	{
		cout<<"时刻 "<<time<<" 结束作业  "<<proc->name<<endl;
        	head=proc->next;
			free(proc);
			proc=NULL;
			if(head==NULL)
			{
				tail=head;
			}
	}
	else
	{
        cout<<"时刻 "<<time<<" 挂起作业  "<<proc->name<<endl;
		cout<<"已经运行了"<<proc->RunTime<<"还需要执行"<<proc->NeedTime<<endl;
		if(proc->next != NULL)
		{
		head=proc->next;
		proc->next=NULL;
		tail->next=proc;
		tail=proc;
		}
	}
      
}

void RoundRobin()
{
	pcb* cur_proc=head;
	pcb* new_proc=NULL;
    while(cur_proc)
	{
        if(cur_proc->state == 'W')
		{
			new_proc=cur_proc;
			RR_RunProccess(new_proc);
		}
        cur_proc=head;
	}
}

void Sort_By_NeedTime()
{
	pcb* prev=head;
	pcb*cur=head->next;
	prev->next=NULL;
    pcb*nxt=NULL;
	
	if( cur && head->NeedTime <= cur->NeedTime)
	{
		cur->next=head;
		head=cur;
	}
	else if(cur)
	{ 
		
		while(cur && prev->next != NULL && prev->next->NeedTime <= cur->NeedTime)
		{
			prev=prev->next;
		}
		nxt=cur->next;
		cur->next=prev->next;
		prev->next=cur;
		cur=nxt;
	}	
	
}
void ShortNeed_Time_RunProccess(pcb *proc)
{
	proc->StartTime=time;
	cout<<"时刻 "<<time<<" 开始执行当前作业  "<<proc->name<<endl;
    proc->RunTime+=TIME_SLICE;
	time+=TIME_SLICE;
	proc->NeedTime=proc->ServiceTime-proc->RunTime;
	if(proc->NeedTime <=0)
	{
		cout<<"时刻 "<<time<<" 结束作业  "<<proc->name<<endl;
		head=proc->next;
		free(proc);
		proc=NULL;
		if(head==NULL)
		{
			tail=head;
		}
	}
	else
	{
        cout<<"时刻 "<<time<<" 挂起作业  "<<proc->name<<endl;
		cout<<"已经运行了"<<proc->RunTime<<"还需要执行"<<proc->NeedTime<<endl;
		Sort_By_NeedTime();
	}

}


void ShortNeed_Time()
{
	pcb* cur_proc=head;
	pcb* new_proc=NULL;
    while(cur_proc)
	{
        if(cur_proc->state == 'W')
		{
			new_proc=cur_proc;
			ShortNeed_Time_RunProccess(new_proc);
		}
        cur_proc=head;
	}
}
void main()
{
    int select=1;
	while(select)
	{
		cout<<"******************************************\n";
		cout<<"*****1.******* 先来先服务算法 ************\n";
		cout<<"*****2.********  时间片轮转   ************\n";
		cout<<"*****3.********  短作业优先   ************\n";
		cout<<"*****4.********  优先级调度   ************\n";
		cout<<"*****5.********  最短剩余时间 ************\n";
		cout<<"*****0.**********退出*********************\n";

	cout<<"请选择:> ";
    cin>>select;
	switch(select)
	{
	case 1:
		FCFS_CreateProccess();
	    FCFS();
		break;
	case 2:
		FCFS_CreateProccess();
	    RoundRobin();
		break;
	case 3:
		ShortJobsCreateProccess();
		FCFS();
		break;
	case 4:
		PrioCreateProccess();
		FCFS();
		break;
	case 5:
		ShortJobsCreateProccess();
		ShortNeed_Time();
		break;
	default:
		break;
	}
	}

}