pagebest.c

来自「一个操作系统试验 虚拟存储器页面转换FIFO算法模拟实现」· C语言 代码 · 共 117 行

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#define null 0
#define len sizeof(struct page)

struct page
{ int num;
  int tag;
  struct page *next;
};


struct page *create(int n)    /*建立分配的内存空间，并初始化，返回头结点*/
{int count=1;
 struct page *p1,*p2,*head;
 head=p2=p1=(struct page *)malloc(len);
 p1->tag=-1;p1->num=-1;
 while(count<n)
 {count++;
  p1=(struct page *)malloc(len);
  p1->tag=-1;p1->num=-1;
  p2->next=p1;
  p2=p1;
 }
 p2->next=null;
 return(head);
}


void FIFO(array,n)
int array[],n;
{int *p;
 struct page *cp,*dp,*head,*new;
 int count=0;
 head=create(n);
 p=array;
 while(*p!=-1)
{ cp=dp=head;
  for(;cp->num!=*p&&cp->next!=null;) cp=cp->next;
  if (cp->num==*p) printf(" ! " );
  else
      { count++;
        cp=head;
        for(;cp->tag!=-1&&cp->next!=null;) cp=cp->next;
        if(cp->tag==-1)
 	  {cp->num=*p;
           cp->tag=0;
	   printf(" * ");
 	  }
        else
          {new=(struct page*)malloc(len);
           new->num=*p;
 	   new->tag=0;
	   new->next=null;
           cp->next=new;
           head=head->next;
	   printf(" %d ",dp->num);
	   free(dp);
          }
      }
  p++;
}
printf("\nQueye Zongshu : %d \n",count);
}

main()
{
	FILE *fp;
	char pt;
	char str[10];
	int i,j=0;
	int page[50],space=0;
	for(i=0;i<50;i++)
	page[i]=-1;
	fp=fopen("page.txt","r+");
	if(fp==NULL)
	{
		printf("Cann't open the file\n");
		exit(0);
        }
	i=0;
	while((pt=fgetc(fp))!=EOF)/*将数字字符串转化成整型—开始*/
	{
		if(pt>='0'&&pt<='9')
		{
			str[i]=pt;i++;
			space=0;
		}
		else
		{
			if(pt==' '||pt=='\n')
			{if(space==1) break;
			 else
			  {str[i]='\0';
			   page[j]=atoi(str);
			   if(pt=='\n') break;
			   else
				{
					space=1;
					j++;
			   		i=0;
			   	}
			  }
			}
		}
	 }/*结束*/
	if(pt==EOF) {str[i]='\0';page[j]=atoi(str);}
	i=0;
	while(page[i]!=-1) {printf(" %d ",page[i]);i++;}
	fclose(fp);
printf("\n");
printf(" ! : mean no moved \n * : mean have free space \n\n");
printf("FIFO ");
FIFO(page,3);
}