spooling.c

包含操作系统原理书籍中所提到的很多方法的实现函数

/*SPOOLING 模拟实验*/
#include<stdio.h>
#include<stdlib.h>
#include<time.h>

struct pcb     
{
	int id;/*进程标识*/
	int status; /*进程状态*/
	int firstaddr; /*信息块首地址*/
	int length; /*输出长度*/
	int outbufword; /*输出缓冲字*/
}*PCB[3];
/*进程状态status的可能取值：
*0：可执行
*1：输出井满等待
*2：输出井空等待
*3：结束
*/

FILE *f;
struct req/*输出请求块*/
{
	int reqname; /*请求进程名*/
	int length;  /*本次输出长度*/
	int addr;    /*地址*/
}reqblock[10];

int buffer[2][100],C3=10; /* buffer为输出井*/
int l1=1, l2=1;
int head= 0, tail= 0; /*输出井的头尾指针*/
int t1, t2;
 
void request(int i)  /*i为请求输出的进程标识“1或2”*/
{
	int j, length= 0,m;
	struct req *run;
	/* 
	   if( (tail-head) == 10)
	   {
	   PCB[i-1].status = 1;
	   return;
	   }
	   */
	if(i == 1)
	{
		t1--;
	}
	else
	{
		t2--;
	}
	   run = &reqblock[tail%10];
       run->reqname = i;
       run->length = 0;
       if (tail == 0)
	   {
		   run->addr= 0;
	   }
	   else
	   {
		   int index = (tail-1)%10;
		   run->addr = reqblock[index].addr + reqblock[index].length;
	   }
	   for(m=0; m < 100; m++)
	   {
		   if(buffer[i-1][m] == 0)
		   {
			   run->addr=m;
			   break;
		   }
	   }
	   while(1)
	   {
		   j = rand()%10;
		   if (j == 0)
		   {
			   run->length=length;
			   break;
		   }
		   buffer[i-1][ ( run->addr + length ) ] = j;
		   length++;
	   }
	   PCB[i-1]->length += length;
	   length = 0;
	   if(PCB[2]->status == 2)
	   {
		   PCB[2]->status=0;
	   }
	   tail++;
}

void spooling()
{
    int i,j;
    struct req * run;
    run = &reqblock[head%10];
    printf("%d  ",run->reqname);
	fprintf(f,"%d  ",run->reqname);
    for(i = 0; i < run->length; i++)
	{
		printf("%d ",buffer[run->reqname-1][run->addr+i]);
		fprintf(f,"%d ",buffer[run->reqname-1][run->addr+i]);
	}
	printf("\n");
	fprintf(f,"\n");
	head++;
	for( j = 0; j < 2; j++)
	{ 
		if(PCB[j]->status == 1)
		{
			PCB[j]->status=0;
		}
	}
}

int main()
{
	int i, j, n;
	f=fopen("result.txt","w");
	for (i = 0; i < 2; i++)
		for (n = 0; n < 100; n++)
			buffer[i][n] = 0;
	for( i = 0; i < 3; i++)
	{
		struct pcb *tmpPcb = (struct pcb*)malloc(sizeof(struct pcb));
		
		tmpPcb->id= i;
		tmpPcb->status= 0;
		tmpPcb->firstaddr= 0;
		tmpPcb->length= 0;
		tmpPcb->outbufword= 1;
		PCB[i] = tmpPcb;
	}
	printf("How many work do p1 want to do?");
	fprintf(f,"How many work do p1 want to do?");
	scanf("%d",&t1);
	fprintf(f,"%d\n",t1);
	printf("How many work do p2 want  to do?");
	fprintf(f,"How many work do p2 want  to do?");
	scanf("%d",&t2);
	fprintf(f,"%d\n",t2);
	srand((unsigned)time(NULL));
	while(1)
	{
		i=rand()%100;                      
		
		if(i <= 45)
		{
			if( (PCB[0]->status == 0) && (t1 > 0) )
			{
				request(1);
			}
		}
		//else 
		else if( (i <= 90) && (t2>0) )                
		{
			if(PCB[1]->status == 0 )
			{
				request(2);
			}
		}
		else
		{
			spooling();
		}
		if( (t1 == 0) &&(t2 == 0)&& (head==tail) )        
			break;
	}
	for( i = 0; i < 3; i++)
	{
		free(PCB[i]);
		PCB[i] = NULL;
	}
	fclose(f);
	return 0;
}

/*
运行程序的结果如下：
How many work do P1 want  to do?9
How many work do P2 want  to do?9
2  3 3 8 9 3
2  8 9 3
2  7
2  8 6 5 5
2  9 3 7
1  3 8 6 8 8 6 1 4 9 8 1 9 9
2
2  5 8
2  1 8 3 5 5 6 5 1 2
2  1 9 7 7 6 4 1 3 9 8 9 4 6 3 3 7 5 6 9 5 7 2
1  7
1  7
1  1 6 7 6 4 7 3 8 9 2 7 2 6
1  1 7 2 4 3 9 6
1  7 2 8 4 4 7 6 5 8 3 8 6 9 8 5 7 5 8 6 3 4 4 4 6 1
1  8 6 2 2 1 8 7 1
1  1 4 4 6 1 6 7 3 1 1 8 5 5 5 6 6 9 8
1  3 2 6 4
*/