新建 文本文档.txt

进程是操作系统实质的关键

#include<stdio.h>
#include<stdlib.h>
#define MAXPRI 100
#define  NIL -1
int s1,s2;
typedef struct messagetp {
	int num;
	struct messagetp *next;
	int pro;
} *message;
 struct procb{
	int id;
	char status;
	int nextwr;
	int priority;
	message  mess;
	int inum;
	char addr;};
 struct semaphore{
	int value;
	int firstwr;
};
struct procb  pcb[4];
struct semaphore sem[3];
char addr;
int i,seed,exe;
int style;
void send(int sender,int receiver,int snum)
{
    struct messagetp *p,*q;
	p=(struct messagetp*)malloc(sizeof( struct messagetp));
    p->num=snum;
	p->next=NULL;
	p->pro=sender;
	printf("send message to process%d.",receiver);
	printf("process%d already run %d times.",sender,snum);
	q=pcb[receiver].mess;
	if(q==NULL)
       pcb[receiver].mess=p;
	else
	{
		while(q->next!=NULL)
		{
			q=q->next;
			q->next=p;
		}
	}
}
void receive( int receiver )
{

  message p;
  p=pcb[receiver].mess;
  if(p!=NULL)
     while(p!=NULL)
	 {
		 printf("\n");
		 printf(" receive message from process %d .",p->pro);
		 printf(" process %d is already run %d times.\n",p->pro,p->num);
	     p=p->next;
	 }
  pcb[receiver].mess=NULL;
}
void init()
{
	int j;
	for(j=1;j<=3;j++)
	{
		pcb[j].id=j;
		pcb[j].status='r';
		pcb[j].nextwr=-1;
		printf("process %d priority?",j);
		scanf("%d",&i);
		pcb[j].priority=i;
		pcb[j].mess=NULL;
		pcb[j].inum=0;
		pcb[j].addr='0';
	}
	sem[1].value=1;
	sem[1].firstwr=-1;
	sem[2].value=1;
	sem[2].firstwr=-1;
	exe=-1;
}
double random()
{
	int m;double t;
	if(seed<=0)
		m=-seed;
	else
	{	m=seed;
	seed=(25173*seed+13849)%65536;
    t=m/32767.0;
	}return t;
}
int  find()
{
	int j,pd,w;
	pd=-1;
	w=MAXPRI;
	for(j=1;j<=3;j++)
	 if(pcb[j].status=='r')
		if(pcb[j].priority<w)
		{
			w=pcb[j].priority;
			pd=j;
		}
    if(pd==-1)
	  for(j=1;j<=3;j++)
	    if(pcb[j].status=='t')
		 if(pcb[j].priority<w)
		 {
			w=pcb[j].priority;
			pd=j;
		 }
    return pd;
}
int scheduler()
{
	int pd;
	pd=find();
	if((pd==-1)&&(exe==-1))
		return -1;
	else
	{  
	  if(pd!=-1)
	  {
		  if(exe==-1)
		  {
			  pcb[pd].status='e';
			  exe=pd;
			  printf("process %d is executing.",exe);
		  }
		  else
			if(pcb[pd].priority<pcb[exe].priority)
			{
				pcb[exe].status='r';
				printf("process %d enter into ready.",exe);
				pcb[pd].status='e';
				exe=pd;
				printf("process %d is executing.",exe);
			}
	  }

	  i=pcb[exe].inum;
	  addr=pcb[exe].addr;
	  return exe;
	}
}
void  block(int se)
{
	int w;
	printf(" process %d is blocked.",exe);
	pcb[exe].status='w';
	pcb[exe].nextwr=-1;
	w=sem[se].firstwr;
	if(w==-1)
		sem[se].firstwr=exe;
	else
		while(pcb[w].nextwr!=-1)
		{
			w=pcb[w].nextwr;
            pcb[w].nextwr=exe;
		}
}
int p(int se,char ad)
{
	sem[se].value--;
	if(	sem[se].value>=0)
	   return 0;
	else
	{
		block(se);
		pcb[exe].inum=i;
		pcb[exe].addr=ad;
		exe=-1;
		return 1;
	}
}
void wakeup(int se)
{
	int w;
	w=sem[se].firstwr;
	if(w!=-1)
	{
		sem[se].firstwr=pcb[w].nextwr;
		pcb[se].status='r';
		printf("process %d is waken up." ,w);
	}
}
int v(int se ,char ad)
{
	sem[se].value++;
	if(	sem[se].value>0)
	   return 0;
	else
	{
		wakeup(se);
		pcb[exe].inum=i;
		pcb[exe].addr=ad;
	   return 1;
	}
}
int timeint(char ad)
{
	double x;
	x=random();
	if((x<0.3)&&(exe==1))
	 return 0;
	else
		if((x<0.6)&&(exe==2))
			return 0;
		else
			if((x<1.0)&&(exe==3))
				return 0;
			else
			{
				pcb[exe].inum=i;
				pcb[exe].addr=ad;
				pcb[exe].status='t';
				printf("Time silce interrupt.\n");
				printf("process %d enter into ready",exe);
				exe=-1;
				return 1;
			}
}
void eexit(int n)
{
	pcb[n].status='c';
	printf("process %d is completed!",n);
	exe=-1;
}
void process1()
{
	if(addr=='a')
	    goto a1;
	if(addr=='b')
	    goto b1;
	if(addr=='c')
	    goto c1;
	if(addr=='d')
	    goto d1;
	if(addr=='e')
	    goto e1;
	if(addr=='f')
	    goto f1;
	while(i<5)
	{ 
		receive(1);
		printf("process 1 calls P on semaphore 1.");
		if(p(1,'a'))
			goto stop1;
a1:{printf("process 1 is executing on its cretical section 1 .");
		     if(timeint('b'))
				 goto stop1;}
b1:{s1=s1+1;
		   printf("\ns1=%d\n",s1);
		   printf("process1 calls V on semaphore 1 and quit cretical section 1.");
		   if(v(1,'c'))
			   goto stop1;}
c1:{printf("process 1 calls P on semaphore 2.");
	       if(p(2,'d'))
			   goto stop1;}
d1:{printf("process 1 is executing  cretical section 2.");
		   if(timeint('e'))
			   goto stop1;}
e1:{s2=s2+1;
		   printf("\ns2=%d\n",s2);
		   printf("process1 calls V on semaphore 2 and quit cretical section 2.");
		   if(v(2,'f'))
			   goto stop1;}
f1:{printf("process 1 cyclen count=%d",i+1);
	       i=i+1;
           send(1,2,i);
		   send(1,3,i);
         }
	}
stop1:{if(i<5)
		  goto end1;
	     eexit(1);}
  end1:;
}
void process2()
{
	if(addr=='a')
	    goto a2;
	if(addr=='b')
	    goto b2;
	if(addr=='c')
	    goto c2;
	if(addr=='d')
	    goto d2;
	if(addr=='e')
	    goto e2;
	if(addr=='f')
	    goto f2;
	while(i<5)
	{ 
		receive(2);
		printf("process 2 calls P on semaphore 2.");
		if(p(2,'a'))
			goto stop2;
        a2:printf("process 2 is executing on its cretical section 2 .");
		   if(timeint('b')) 
			  goto stop2;
        b2:s2=s2+1;
		   printf("\ns2=%d\n",s2);
		   printf("process 2 calls V on semaphore 2 and quit cretical section 2.");
		   if(v(2,'c'))
			   goto stop2;
        c2:printf("process 2 calls P on semaphore 1.");
	       if(p(1,'d'))
			goto stop2;
        d2:printf("process 2 is executing  cretical section 1.");
		   if(timeint('e'))
			   goto stop2;
        e2:s1=s1+1;
		   printf("\ns1=%d\n",s1);
		   printf("process 2 calls V on semaphore 1 and quit cretical section 1.");
		   if(v(1,'f'))
			   goto stop2;
        f2:printf("process 2 cyclen count=%d",i+1);
	       i=i+1;
           send(2,1,i);
		   send(2,3,i);
          
	}
   stop2:if(i<5)
		  goto end2;
	     eexit(2);
   end2:;
}

void process3()
{
	if(addr=='a')
	    goto a3;
	if(addr=='b')
	    goto b3;
	if(addr=='c')
	    goto c3;
    while(i<5)
	{ 
		receive(3);
		printf("process 3 calls P on semaphore 2.");
		if(p(2,'a'))
			goto stop3;
        a3:printf("process 3 is executing on its cretical section 2 .");
		   if(timeint('b')) 
			  goto stop3;
        b3:s2=s2+1;
		   printf("\ns2=%d\n",s2);
		   printf("process 3 calls V on semaphore 2 and quit cretical section 2.");
		   if(v(2,'c'))
			   goto stop3;
        c3:printf("process 3 cyclen count=%d",i+1);
	        i=i+1;
           send(3,1,i);
		   send(3,2,i);
         
	}
   stop3:if(i<5)
		  goto end3;
	     eexit(3);
   end3:;

}

/*

  void  creat(int n)
  {
       procb a;

    	a.id=j;
		a.status='r';
		a.nextwr=-1;
         a.priority=n;
		a.mess=NULL;
		a.inum=0;
		a.addr='0';
		}
		*/
void main()
{
	int k; 
	printf("**********************C.O.S  Example one******************************\n");
	init();
	s1=0;
	s2=0;
    printf("\ns1=%d,s2=%d\n",s1,s2);	
	printf("process1,process2,process3 are all in ready!\n");
ll:k=scheduler();
    if(k!=-1)
	{   switch(k)
	   {
		   case 1:{ process1(); goto ll ;break;}
           case 2:{ process2(); goto ll ;break;}
	       case 3:{ process3(); goto ll ;break;}
		   default:printf("process identifer error.\n"); 
	   }
	}
   printf("\n\n");
   printf("\ns1=%d,s2=%d\n",s1,s2);
   printf("**********************  Completed!!    ******************************\n");
   getchar();
}