diskmem.c

用位示图管理磁盘空间的分配与回收

#include <stdio.h>
#include <process.h>

void Initbitmap(int map[8][8])
{
 int cylinder,track,sector;
 char choice='Y';
 printf("初始化位视图...\n");
 while(choice=='y'||choice=='Y')
 {
  printf("柱面号:");
  scanf("%d",&cylinder);
  printf("磁道号:");
  scanf("%d",&track);
  printf("物理记录号:");
  scanf("%d",&sector);
  map[cylinder][4*track+sector]=1;
  printf("contiune?");
  getchar();
  scanf("%c",&choice);
  
 }
}
 
void allocate(int map[8][8])
{
  int i,j;
  int flag=0;
  int cylinder,track,sector; 
  for(i=0;i<8;i++)
      { for(j=0;j<8;j++)
        if(map[i][j]==0) {map[i][j]=1;flag=1;break;} 
        if(flag==1) break;
      }
  if(flag==1)
  {  
    cylinder=i;
    track=j/4;
    sector=j%4;
    printf("分配到的柱面号、磁道号、物理记录数");
    printf("%d\t%d\t%d",cylinder,track,sector);
	printf("\n");
  }
 else printf("空间不足，分配失败!");
}

void reclaim(int map[8][8])
{ int cylinder,track,sector;
  printf("柱面号:");
  scanf("%d",&cylinder);
  printf("磁道号:");
  scanf("%d",&track);
  printf("物理记录号:");
  scanf("%d",&sector);
  if(map[cylinder][4*track+sector]==0)
  {
	  printf("此块为未分配块！回收出错！");
      getchar();
  }
  else
  {
	  map[cylinder][4*track+sector]=0;
      printf("回收块对应的字节号:%4d\t位数:%4d\n",cylinder,4*track+sector);
  
  }
}

void main()
{
int bitmap[8][8];
int i,j;
int choice;
for(i=0;i<8;i++)
   for(j=0;j<8;j++)
        bitmap[i][j]=0;
Initbitmap(bitmap);

while(1)
{
  printf("\n请输入选择:");
  printf("1--分配，2---回收，3--显示位示图，0--退出\n");
  scanf("%d",&choice);  
  switch(choice)
  {
   case 1:allocate(bitmap);break;
   case 2:reclaim(bitmap);break;
   case 3:for(i=0;i<8;i++)
                 {for(j=0;j<8;j++)
                  printf("%8d",bitmap[i][j]);
                  printf("\n");
                  }
	        break;
                
   case 0:exit(0);
   default:printf("错误选择！");break;
  
  }
}
}