fat32.c

os arm os arm os arm os arm os arm os arm os arm os arm os arm os arm os arm os arm os arm os arm

#include "../include/fs/fat32.h"

#define PHY_SECT(n)	(n)
#define SECTS(n)	(n)

//获得磁盘簇clus所对应的第一个扇区号
#define FIRST_SECT_CLUST(clus) \
((clus-2)*super_block.SecPerClus)+first_data_sector

#define BUF_LEN	1024
extern char 	sys_dma2_done;

struct super_block super_block;
FAT32_DIR_ENTRY_SHORT *fat32_dir_entry_short;
FAT32_DIR_ENTRY_LONG *fat32_dir_entry_long;
unsigned char 	fs_buf[BUF_LEN] __attribute__ ((aligned(4)));
unsigned int 	root_dir_secs;	//根目录占用的扇区数，对FAT32来说为0
unsigned int 	fat_sz;			//FAT区域占用的扇区数
unsigned int 	total_sec;		//文件系统的总扇区数
unsigned int 	data_sec;		//文件系统中存放文件数据的扇区数目
unsigned int 	data_clus;		//文件系统中存放文件数据的磁盘簇数目
unsigned int 	first_data_sector;	//文件系统中存放文件数据的第一个扇区号
unsigned int 	current_clus;		//当前目录的簇号


void dump_fs_info()
{
	printk("BytsPerSec 	:0x%0x\n",super_block.BytsPerSec);
	printk("SecPerClus 	:0x%0x\n",super_block.SecPerClus);
	printk("RsvdSecCnt 	:0x%0x\n",super_block.RsvdSecCnt);
	printk("NumFATs 	:0x%0x\n",super_block.NumFATs);
	printk("RootEntCnt 	:0x%0x\n",super_block.RootEntCnt);
	printk("TotSec16 	:0x%0x\n",super_block.TotSec16);
	printk("Media 		:0x%0x\n",super_block.Media);
	printk("FATSz16 	:0x%0x\n",super_block.FATSz16);
	printk("SecPerTrk 	:0x%0x\n",super_block.SecPerTrk);
	printk("NumHeads 	:0x%0x\n",super_block.NumHeads);
	printk("HiddSec 	:0x%0x\n",super_block.HiddSec);
	printk("TotSec32 	:0x%0x\n",super_block.TotSec32);
	
	printk("FAT32_FATSz32 	:0x%0x\n",super_block.FAT32_FATSz32);
	printk("FAT32_ExtFlags 	:0x%0x\n",super_block.FAT32_ExtFlags);
	printk("FAT32_FSVer 	:0x%0x\n",super_block.FAT32_FSVer);
	printk("FAT32_RootClus 	:0x%0x\n",super_block.FAT32_RootClus);
	printk("FAT32_FSInfo 	:0x%0x\n",super_block.FAT32_FSInfo);
	printk("FAT32_BkBootSec :0x%0x\n",super_block.FAT32_BkBootSec);
	printk("FAT32_DrvNum 	:0x%0x\n",super_block.FAT32_DrvNum);
	printk("FAT32_BootSig 	:0x%0x\n",super_block.FAT32_BootSig);
	printk("FAT32_VolID 	:0x%0x\n",super_block.FAT32_VolID);

}

/*
 *	读0号扇区初始化超级块
 */
void init_super_block()
{
	sdRead(0,1,fs_buf);
	
	*(((char *)&super_block.BytsPerSec)+0)	=*((unsigned char *)(fs_buf+BPB_BYTES_PER_SEC));
	*(((char *)&super_block.BytsPerSec)+1)	=*((unsigned char *)(fs_buf+BPB_BYTES_PER_SEC+1));
	super_block.SecPerClus			=*((unsigned char *)(fs_buf+BPB_SEC_PER_CLUS));
	super_block.RsvdSecCnt			=*((unsigned short *)(fs_buf+BPB_RSVD_SEC_CNT));
	super_block.NumFATs			=*((unsigned char *)(fs_buf+BPB_NUM_FATS));
	*(((char *)&super_block.RootEntCnt)+0)	=*((unsigned char *)(fs_buf+BPB_ROOT_ENT_CNT));
	*(((char *)&super_block.RootEntCnt)+1)	=*((unsigned char *)(fs_buf+BPB_ROOT_ENT_CNT+1));
	super_block.TotSec16			=*((unsigned short *)(fs_buf+BPB_TOT_SEC16));
	super_block.Media			=*((unsigned char *)(fs_buf+BPB_MEDIA));
	super_block.FATSz16			=*((unsigned short *)(fs_buf+BPB_FATSZ16));
	super_block.SecPerTrk			=*((unsigned short *)(fs_buf+BPB_SEC_PER_TRK));
	super_block.NumHeads			=*((unsigned short *)(fs_buf+BPB_NUM_HEADS));
	super_block.HiddSec			=*((unsigned int *)(fs_buf+BPB_HIDD_SEC));
	super_block.TotSec32			=*((unsigned int *)(fs_buf+BPB_TOT_SEC32));
	super_block.FAT32_FATSz32		=*((unsigned int *)(fs_buf+BPB_FAT32_FATSZ32));
	super_block.FAT32_ExtFlags		=*((unsigned short *)(fs_buf+BPB_FAT32_EXT_FLAGS));
	super_block.FAT32_FSVer			=*((unsigned short *)(fs_buf+BPB_FAT32_FSVER));
	super_block.FAT32_RootClus		=*((unsigned int *)(fs_buf+BPB_FAT32_ROOT_CLUS));
	super_block.FAT32_FSInfo		=*((unsigned short *)(fs_buf+BPB_FAT32_FS_INFO));
	super_block.FAT32_BkBootSec		=*((unsigned short *)(fs_buf+BPB_FAT32_BKBOOT_SEC));
	super_block.FAT32_DrvNum		=*((unsigned char *)(fs_buf+BS_FAT32_DRV_NUM));
	super_block.FAT32_BootSig		=*((unsigned char *)(fs_buf+BS_FAT32_BOOT_SIG));
	super_block.FAT32_VolID			=*((unsigned int *)(fs_buf+BS_FAT32_VOL_ID));
}




/*
 *	本函数根据超级块中的数据判断文件系统的类型
 *	目前只支持FAT32
 */
char dete_fat_type()
{
	/*
	 *	root_dir_secs为文件系统根目录所占用的扇区,
	 *	FAT32的root_dir_secs为0
	 */
	root_dir_secs =((super_block.RootEntCnt*32)+
			(super_block.BytsPerSec-1))/
			super_block.BytsPerSec;
	
	//获得fat区占用的扇区数
	if(super_block.FATSz16!=0)
		fat_sz=super_block.FATSz16;
	else
		fat_sz=super_block.FAT32_FATSz32;
	
	//获得文件系统中的扇区总数
	if(super_block.TotSec16!=0)
		total_sec=super_block.TotSec16;
	else
		total_sec=super_block.TotSec32;
	
	/*
	 *	获得文件系统中存放文件数据的扇区数
	 *	存放数据的扇区数=总扇区数-保留扇区数-fat扇
	 *	区数-根目录占用的扇区数
	 */
	data_sec=total_sec-(super_block.RsvdSecCnt+
		(super_block.NumFATs*fat_sz)+
		root_dir_secs);
	
	//获得文件系统中存放文件数据的的磁盘簇数目
	data_clus=data_sec/super_block.SecPerClus;
	
	//根据data_clus的数目判断本文件系统的类型
	if(data_clus<4085)
	{
		return FAT12;
	}
	else if(data_clus<65525)
	{
		return FAT16;
	}
	else
	{
		return FAT32;
	}
		
}



/*


void ShowDate(unsigned short date)
{
    printk("%d-",((date>>9)&0x7f)+1980);
    printk("%d-",(date>>5)&0xf);
    printk("%d",date&0x1f);    
}

void ShowTime(unsigned short time)
{
    printk("%d:",((time>>11)&0x1f));
    printk("%d:",(time&0x1f)*2);
    printk("%d",(time>>5)&0x3f);
}

void ShowShortName(unsigned char *buf)
{
	int i;
	for(i=0;i<11;i++)
		printk("%c",buf[i]);
}

void ShowLongName(FAT32_DIR_ENTRY_LONG *long_entry)
{
	printk("%s",fat32_dir_entry_long->LDIR_Name1);
	printk("%s",fat32_dir_entry_long->LDIR_Name2);
	printk("%s",fat32_dir_entry_long->LDIR_Name3);
}

unsigned int get_root_dir()
{
	unsigned int next_clus=super_block.FAT32_RootClus;
	int j;
	int k;
	int entry;
	int long_entry_counter;
	
	do
	{
		sdRead(FIRST_SECT_CLUST(next_clus),2,(unsigned char *)fs_buf);
		entry=0;
		long_entry_counter=0;
		while(entry<1024/32)
		{
			fat32_dir_entry_short=(FAT32_DIR_ENTRY_SHORT *)fs_buf+entry;
			//是一个long entry
			if(fat32_dir_entry_short->Dir_Attr==ATTR_LONG_NAME)
			{
				entry++;
				long_entry_counter++;
				continue;
			}
			else//是一个short entry
			{
				if(fat32_dir_entry_short->Dir_Name[0]==0xe5)
				{
					entry++;
					long_entry_counter=0;
					continue;
				}
				if(fat32_dir_entry_short->Dir_Name[0]==0x00)
				{
					long_entry_counter=0;
					break;
				}
				//directory entry完全有short entry组成
				if(long_entry_counter==0)
				{
					ShowShortName(fat32_dir_entry_short->Dir_Name);
					printk(" ");
				}
				else//directory entry由short entry和long entry组成
				{
					for(k=1;k<=long_entry_counter;k++)
					{
						fat32_dir_entry_long=(FAT32_DIR_ENTRY_LONG *)fat32_dir_entry_short-k;
						ShowLongName(fat32_dir_entry_long);
					}
					printk(" ");
				}

				ShowDate(fat32_dir_entry_short->DIR_CrtDate);
				printk(" ");
				ShowTime(fat32_dir_entry_short->DIR_CrtTime);
				printk(" ");
				printk("0x%0x",fat32_dir_entry_short->Dir_Attr);
				printk("\n");
				
				entry++;
				long_entry_counter=0;
			}
		}
	}while((next_clus=FAT32_entry(next_clus))&0x0fffffff!=0x0fffffff);
	printk("show root done.\n");
	
	return 1;
}

*/

/*
 *	根据磁盘簇号获得该磁盘簇对应的FAT条目
 */
unsigned int get_fat_entry(unsigned int cluster_num)
{
	unsigned int FAT32_SECTNUM=super_block.RsvdSecCnt+
			((cluster_num*4)/super_block.BytsPerSec);
	
	unsigned int FAT32_ENT_OFFSET=(cluster_num*4)%super_block.BytsPerSec;
	
	unsigned int fat32_entry;

	sdRead(FAT32_SECTNUM,1,&fs_buf);
	fat32_entry=(*((unsigned int *)fs_buf[FAT32_ENT_OFFSET]))&0x0FFFFFFF;
	return fat32_entry;
}

//获得根目录的簇号
unsigned int get_root_clus()
{
	return super_block.FAT32_RootClus;
}


/*
 *	获得第一个存放文件数据的扇区号
 */
unsigned int get_first_data_sec()
{
	unsigned int sec=super_block.RsvdSecCnt+
		(super_block.NumFATs * super_block.FAT32_FATSz32) +
		root_dir_secs;
	
	return sec;
}

int mount_fat32()
{
	//初始化super_block
	init_super_block();
	//打印超级块信息
	//dump_fs_info();
	
	if(dete_fat_type()!=FAT32)
	{
		return -1;
	}
	
	//系统启动的时候当前磁盘簇为根目录磁盘簇
	current_clus=get_root_clus();
	
	//获得文件系统中第一个存放文件数据的扇区号
	first_data_sector=get_first_data_sec();

	//get_root_dir();
	
	return 1;
}