pcd.c

这它用C语言编写的实现模拟进程调度的程序

//进程调度-----优先级算法源程序
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>

typedef struct node              //创建PCB     
{
	char name[10];               //进程标识
    int prio;                    //进程优先数
    int cputime;                 //进程占用CPU时间
    int needtime;                //进程完成所需时间
    int count;                   //计数器
    char state;                  //进程的状态
    struct node *next;           //链指针
}PCB;
PCB *finish,*ready,*tail,*run;
int N;
 
firstin()                        //创建就绪队列对头指针
{
   run=ready;  
   run->state='R';  
   ready=ready->next; 
}
 
 
void prt(char algo)              //演示进程调度
{
   PCB *p;
   printf("   NAME  CPUTIME   NEEDTIME   PRIORITY   STATUS\n");
   if(run!=NULL)
   printf("  %-10s%-10d%-10d%-10d %c\n",run->name,
       run->cputime,run->needtime,run->prio,run->state); 
   p=ready; 
   while(p!=NULL)
   {  printf("  %-10s%-10d%-10d%-10d %c\n",p->name,
      p->cputime,p->needtime,p->prio,p->state);
      p=p->next;
   }
   p=finish; 
   while(p!=NULL)
   {  printf("  %-10s%-10d%-10d%-10d %c\n",p->name,
      p->cputime,p->needtime,p->prio,p->state);
      p=p->next;
   }
   printf("************************************************\n");
   getch();
}
 
insert(PCB *q)
{
   PCB *p1,*s,*r;
   int b;
   s=q;
   p1=ready;
   r=p1;
   b=1;
   while((p1!=NULL)&&b)
      if(p1->prio>=s->prio)
      {
		  r=p1;
		  p1=p1->next;
      }
	  else
      b=0;
	  if(r!=p1)
	  {
		  r->next=s;
          s->next=p1;
	  }
	  else
	  {
		  s->next=p1;
          ready=s;
	  }
}
 



void create(char alg)                //创建各个进程
{
   PCB *p;
   int i,time,priority;
   char na[10];
   ready=NULL;
   finish=NULL;
   run=NULL;
   for(i=1;i<=N;i++)
   {
      p=malloc(sizeof(PCB));
      printf("\nEnter NAME of the NO.%d process:\n",i);
      scanf("%s",na);
loop1:
      printf("Enter TIME of process(less than 10 is better):\n");
      scanf("%d",&time);
	  if(time<=0)
	  {
		  printf("Time can't below zero,Please Enter AGain:\n");//时间不能小于或等于零
		  goto loop1;
	  }
	  printf("Enter PRIORITY of process:\n");
	  scanf("%d",&priority);
      strcpy(p->name,na);
      p->cputime=0;
      p->needtime=time;
      p->state='R';                     //R为就绪状态
      p->prio=priority;               
	  if(ready!=NULL)
      insert(p);
      else
	  {
		  p->next=ready;
          ready=p;
      }
   }
   printf("          DISPLAY OF THE PROGRESS:\n");
   printf("************************************************\n");
   prt(alg);
   run=ready;
   ready=ready->next;
   run->state='W';                     //除就绪和结束状态的其它状态
}
 


priority(char alg)                   //优先级算法调度
{
   while(run!=NULL&&run->prio>=0)
   {
      run->cputime=run->cputime+1;
      run->needtime=run->needtime-1;
      run->prio=run->prio-1;
      if(run->needtime==0)
      {
		  run->next=finish;
          finish=run;
          run->state='E';                 //E为结束状态
          run=NULL;
          if(ready!=NULL)
          firstin();
      }
      else
		  if((ready!=NULL)&&(run->prio<ready->prio))
		  {
			  run->state='R';
			  insert(run);
              firstin();          //创建就绪队列对头指针
		  }
		  prt(alg);               //演示进程调度
   }
}
 


main()                            //主函数
{
	char algo;
	printf("\n\n");
	printf("\t\t\t******模拟进程调度程序演示******\n");
loop:
	printf("****Enter THE TOTAL NUMBER of PCB(less than 10):\n");
    scanf("%d",&N);
    if(N<=0||N>10)
	{
		printf("Your input NUMBER is too big or less than 1.\n");
		printf("Enter AGAIN:\n\n");
        goto loop;
	}
	create(algo);
    priority(algo);
}