sched.cpp

几个实现操作系统算法的小程序 有哲学家 算法 生产者消费者等算法的实现 供初学者学习参考

#include <stdio.h>
#include <stdlib.h>
#define MaxProc 10//最大进程数
#define INF 1000//无穷大

int COUNT;//实际里程数

struct _PCB
{//进程控制块
	int ID;//进程ID
	int Time_server;//进程的服务时间
	int Time_arrive;//进程的到达时间
	int Time_start;//进程的开始时间
	int Time_over;//进程的结速时间
};
typedef struct _PCB PCB;


void ReadProcess(PCB * head);
int SPF_sched(PCB * head);//最短进程优先调度
int RR_sched(PCB * head);//轮转调度

int main()
{
	int choose;
	int i =0;
	PCB process[MaxProc];//进程运行队列

back:	
	ReadProcess( process );
	//显示选择信息
	printf("\t1. Shortest Process First(SPF)\n"
           "\t2. Round Robin(RR)\n"
		   "\t3. Concel\n"
           "\tPlease input your choose: ");
	scanf("%d", &choose);
	
	while(1)
	{//根据选择进行相应处理
		switch(choose)
		{ 
		case 1:
			printf("The shortest process first algorithm:\n");
			SPF_sched( process );
			goto back;
		case 2:
			printf("The round robin algorithm:\n");
			RR_sched( process );
			goto back;
		case 3:
			goto over;
		default:
			printf(" No that choice!!!\n");
			goto over;
		}
	}

over:
	printf("Over!\n");
	return 0;
}

void ReadProcess( PCB * head )
{//从process.txt文件中读取进程数和进程信息
	int i =0;
	FILE * fp;

	if( !(fp = fopen("process.txt","r")))
	{
		printf("Read process fail!!!\n");
		return ;
	}
	
	fscanf(fp,"%d",&COUNT);//读取进程数

	for( ; i < COUNT; i++ )
	{//从文件中读取进程
		fscanf(fp,"%d %d %d", &head[i].ID, &head[i].Time_server, &head[i].Time_arrive);
		head[i].Time_start = head[i].Time_arrive;//设置里程的运行时间为到达时间
		head[i].Time_over = 0;
	}
}

int SPF_sched(PCB * head)
{//对不是同时到达的进程也适用
	PCB * ExecProc = head;
	int i,j;
	int startTime = 0;//记录下一进程的开始运行时间
	int overTime[MaxProc];//记录运行完成进程的结束时间

	for( i = 0; i < COUNT; i++)
	{
		for(j = 0; j < COUNT; j++ )
		{//寻找最早最短的进程
			if( head[j].Time_server < ExecProc -> Time_server && head[j].Time_start <= ExecProc -> Time_start)
					ExecProc = &head[j];
		}
		
		ExecProc -> Time_over = ExecProc -> Time_start + ExecProc -> Time_server;
		ExecProc -> Time_server = INF;//结速进程的服务时间和开始时间设为无穷大
		ExecProc -> Time_start = INF;
		startTime = ExecProc -> Time_over;
		overTime[i] = startTime;
		printf("%d\t", ExecProc -> ID);

		for( j = 0; j < COUNT; j++)
		{//设置在运行过程中到达的进程的开始运行时间
			if( head[j].Time_start < startTime )
				head[j].Time_start = startTime;
		}
	}

	printf("\n");
	for( i = 0; i < COUNT; i++)
		printf("%d\t", overTime[i]);
	printf("\n");
	return 1;
}

int RR_sched(PCB * head)
{//对不同时到达的进程也适用
	int timeSlice = 1;//时间片
	int startTime = 0;//进程开始运行时间
	int i = 0, flag = 0;
	while( 1 )
	{
		if( i == COUNT )	i = 0;

		if( head[i].Time_start <= startTime && head[i].Time_over < head[i].Time_server )
		{
			head[i].Time_start = startTime;
			head[i].Time_over += timeSlice;
			startTime += timeSlice;
			printf("%d ", head[i].ID);//输出运行进程的ID
			
			if( head[i].Time_over == head[i].Time_server )
			{
				head[i].Time_over = startTime;//记录完成进程的结束时间
				flag++;//记录运行完进程数
			}
		}
		
		i++;
		if( flag == COUNT )
			break;//进程全部运行完毕,退出循环
	}

	printf("\nthe process finished time:\n");
	for( i = 0; i < COUNT; i++)//输出进程的ID
		printf("%d\t", head[i].ID);

	printf("\n");
	for( i = 0; i < COUNT; i++)//输出进程的结束时间
		printf("%d\t", head[i].Time_over);

	printf("\n");
	return 1;
}