rr.c

os课程设计会用到

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
typedef struct node
{
   char name[10];  /*进程标识符*/
   int prio;   /*进程优先数*/
   int round;  /*进程时间轮转时间片*/
   int cputime; /*进程占用CPU时间*/
   int needtime; /*进程到完成还要的时间*/
   int count;  /*计数器*/
   char state; /*进程的状态*/
   struct node *next; /*链指针*/
}PCB;
PCB *finish,*ready,*tail,*run; /*队列指针*/
int N; /*进程数*/
/*将就绪队列中的第一个进程投入运行*/
firstin()
{
   run=ready;   /*就绪队列头指针赋值给运行头指针*/
   run->state='R';   /*进程状态变为运行态*/
   ready=ready->next;  /*就绪对列头指针后移到下一进程*/
}
/*标题输出函数*/
void prt1(char a)
{
   if(toupper(a)=='P') /*优先数法*/
      printf("  name     cputime  needtime  priority  state\n");
   else
      printf("  name     cputime  needtime   count   round     state\n");
}
/*进程PCB输出*/
void prt2(char a,PCB *q)
{
   if(toupper(a)=='P')  /*优先数法的输出*/
      printf("  %-10s%-10d%-10d%-10d %c\n",q->name,
       q->cputime,q->needtime,q->prio,q->state);
   else/*轮转法的输出*/
      printf("  %-10s%-10d%-10d%-10d%-10d %-c\n",q->name,
       q->cputime,q->needtime,q->count,q->round,q->state);
}
/*输出函数*/
void prt(char algo)
{
   PCB *p;
   prt1(algo);  /*输出标题*/
   if(run!=NULL) /*如果运行指针不空*/
      prt2(algo,run); /*输出当前正在运行的PCB*/
   p=ready;  /*输出就绪队列PCB*/
   while(p!=NULL)
   {
      prt2(algo,p);
      p=p->next;
   }
   p=finish;  /*输出完成队列的PCB*/
   while(p!=NULL)
   {
      prt2(algo,p);
      p=p->next;
   }
   getch();  /*压任意键继续*/
}

/*轮转法插入函数*/
insert2(PCB *p2)
{
   tail->next=p2;  /*将新的PCB插入在当前就绪队列的尾*/
   tail=p2;
   p2->next=NULL;
}


/*轮转法创建进程PCB*/
void create2(char alg)
{
   PCB *p;
   int i,time;
   char na[10];
   ready=NULL;
   finish=NULL;
   run=NULL;
   printf("Enter name and time of round process\n");
   for(i=1;i<=N;i++)
   {
      p=malloc(sizeof(PCB));
      scanf("%s",na);
      scanf("%d",&time);
      strcpy(p->name,na);
      p->cputime=0;
      p->needtime=time;
      p->count=0; /*计数器*/
      p->state='w';
      p->round=2;  /*时间片*/
      if(ready!=NULL)
  insert2(p);
      else
      {
  p->next=ready;
  ready=p;
  tail=p;
      }
   }
   clrscr();
   printf("              output of round\n");
   printf("************************************************\n");
   prt(alg);   /*输出进程PCB信息*/
   run=ready;  /*将就绪队列的第一个进程投入运行*/
   ready=ready->next;
   run->state='R';
}

/*时间片轮转法*/
roundrun(char alg)
{
   while(run!=NULL)
   {
      run->cputime=run->cputime+1;
      run->needtime=run->needtime-1;
      run->count=run->count+1;
      if(run->needtime==0)/*运行完将其变为完成态，插入完成队列*/
      {
  run->next=finish;
  finish=run;
  run->state='F';
  run=NULL;
  if(ready!=NULL)
     firstin(); /*就绪对列不空，将第一个进程投入运行*/
      }
      else
  if(run->count==run->round)  /*如果时间片到*/
  {
     run->count=0;  /*计数器置0*/
     if(ready!=NULL) /*如就绪队列不空*/
     {
        run->state='W'; /*将进程插入到就绪队列中等待轮转*/
        insert2(run);
        firstin(); /*将就绪对列的第一个进程投入运行*/
     }
  }
      prt(alg); /*输出进程信息*/
   }
}
/*主函数*/
main()
{
   clrscr();
   printf("welcome to the roundrobin algorithm!\n");
   printf("Enter process number\n");
   scanf("%d",&N); /*输入进程数*/
   
   
  create2('r'); /*轮转法*/
  roundrun('r');
      
}