1.c

抢占式的优先级调度

#include "stdio.h"
#include "stdlib.h"
#include "string.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;
   }
   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;
   int prior;
   char na[10];
   ready=NULL;
   finish=NULL;
   run=NULL;
    for(i=1;i<=N;i++)
   {
      p=malloc(sizeof(PCB));
      printf("Enter NAME of process:\n");
      scanf("%s",na);
      printf("Enter TIME of process(less than 50):\n");
      scanf("%d",&time);
      printf("Enter priority of process(less than 50):\n");
      scanf("%d",&prior);
      strcpy(p->name,na);
      p->cputime=0;
      p->needtime=time;
      p->prio=prior;
      p->state='w';
      if(ready!=NULL)
     insert(p);
      else
      {
     p->next=ready;
     ready=p;
      }
   }
   clrscr();
   printf("          DISPLAY OF THE PROGRESS:\n");
   printf("************************************************\n");
   prt(alg);
   run=ready;
   ready=ready->next;
   run->state='R';
}
 
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='F';
     run=NULL;
     if(ready!=NULL)
       firstin();
      }
      else
     if((ready!=NULL)&&(run->prio<ready->prio))
     {
        run->state='W';
        insert(run);
        firstin();
     }
      prt(alg);
   }
}
 
main()
{  char algo;
   clrscr();
loop:    printf("Enter THE TOTAL NUMBER of PCB(less than 10 is better):\n");
   scanf("%d",&N);
   if(N>10)
   {printf("it's too big,and select a small number.\n");
   goto loop;}
   create(algo);
   priority(algo);
   getch();
}