tff.c

基于AVR UC/OS-II的FAT32文件系统。

/*-----------------------------------------------------------------------*/

#if _FS_READONLY == 0
static
BYTE* reserve_direntry (	/* !=NULL: successful, NULL: failed */
	DIR *dirobj				/* Target directory to create new entry */
)
{
	CLUST clust;
	DWORD sector;
	BYTE c, n, *dptr;
	FATFS *fs = FatFs;


	/* Re-initialize directory object */
	clust = dirobj->sclust;
	if (clust) {	/* Dyanmic directory table */
		dirobj->clust = clust;
		dirobj->sect = clust2sect(clust);
	} else {		/* Static directory table */
		dirobj->sect = fs->dirbase;
	}
	dirobj->index = 0;

	do {
		if (!move_window(dirobj->sect)) return NULL;
		dptr = &fs->win[(dirobj->index & 15) * 32];		/* Pointer to the directory entry */
		c = *dptr;
		if (c == 0 || c == 0xE5) return dptr;			/* Found an empty entry! */
	} while (next_dir_entry(dirobj));					/* Next directory pointer */
	/* Reached to end of the directory table */

	/* Abort when static table or could not stretch dynamic table */
	if (!clust || !(clust = create_chain(dirobj->clust))) return NULL;
	if (!move_window(0)) return 0;

	fs->winsect = sector = clust2sect(clust);			/* Cleanup the expanded table */
	memset(fs->win, 0, 512);
	for (n = fs->sects_clust; n; n--) {
		if (disk_write(0, fs->win, sector, 1) != RES_OK) return NULL;
		sector++;
	}
	fs->winflag = 1;
	return fs->win;
}
#endif /* _FS_READONLY */




/*-----------------------------------------------------------------------*/
/* Load boot record and check if it is a FAT boot record                 */
/*-----------------------------------------------------------------------*/

static
BYTE check_fs (		/* 0:Not a boot record, 1:Valid boot record but not a FAT, 2:FAT boot record */
	DWORD sect		/* Sector# to check if it is a FAT boot record or not */
)
{
	FATFS *fs = FatFs;

	if (disk_read(0, fs->win, sect, 1) != RES_OK)	/* Load boot record */
		return 0;
	if (LD_WORD(&fs->win[510]) != 0xAA55)			/* Check record signature */
		return 0;

	if (!memcmp(&fs->win[54], "FAT", 3))			/* Check FAT signature */
		return 2;
#if _FAT32 != 0
	if (!memcmp(&fs->win[82], "FAT32", 5) && !(fs->win[40] & 0x80))
		return 2;
#endif
	return 1;
}




/*-----------------------------------------------------------------------*/
/* Make sure that the file system is valid                               */
/*-----------------------------------------------------------------------*/

static
FRESULT auto_mount (		/* FR_OK(0): successful, !=0: any error occured */
	const char **path,		/* Pointer to pointer to the path name (drive number) */
	BYTE chk_wp				/* !=0: Check media write protection for wrinting fuctions */
)
{
	BYTE fmt;
	DSTATUS stat;
	DWORD basesect, fatsize, totalsect, maxclust;
	const char *p = *path;
	FATFS *fs = FatFs;



	while (*p == ' ') p++;	/* Strip leading spaces */
	if (*p == '/') p++;		/* Strip heading slash */
	*path = p;				/* Return pointer to the path name */

	/* Is the file system object registered? */
	if (!fs) return FR_NOT_ENABLED;

	/* Chekck if the logical drive has been mounted or not */
	if (fs->fs_type) {
		stat = disk_status(0);
		if (!(stat & STA_NOINIT)) {				/* If the physical drive is kept initialized */
#if _FS_READONLY == 0
			if (chk_wp && (stat & STA_PROTECT))	/* Check write protection if needed */
				return FR_WRITE_PROTECTED;
#endif
			return FR_OK;						/* The file system object is valid */
		}
	}

	/* The logical drive has not been mounted, following code attempts to mount the logical drive */

	memset(fs, 0, sizeof(FATFS));		/* Clean-up the file system object */
	stat = disk_initialize(0);			/* Initialize low level disk I/O layer */
	if (stat & STA_NOINIT)				/* Check if the drive is ready */
		return FR_NOT_READY;
#if _FS_READONLY == 0
	if (chk_wp && (stat & STA_PROTECT))	/* Check write protection if needed */
		return FR_WRITE_PROTECTED;
#endif

	/* Search FAT partition on the drive */
	fmt = check_fs(basesect = 0);		/* Check sector 0 as an SFD format */
	if (fmt == 1) {						/* Not a FAT boot record, it may be patitioned */
		/* Check a partition listed in top of the partition table */
		if (fs->win[0x1C2]) {						/* Is the 1st partition existing? */
			basesect = LD_DWORD(&fs->win[0x1C6]);	/* Partition offset in LBA */
			fmt = check_fs(basesect);				/* Check the partition */
		}
	}
	if (fmt != 2 || fs->win[12] != 2)			/* No valid FAT patition is found */
		return FR_NO_FILESYSTEM;

	/* Initialize the file system object */
	fatsize = LD_WORD(&fs->win[22]);					/* Number of sectors per FAT */
	if (!fatsize) fatsize = LD_DWORD(&fs->win[36]);
	fs->sects_fat = (CLUST)fatsize;
	fs->n_fats = fs->win[16];							/* Number of FAT copies */
	fatsize *= fs->n_fats;		/* Number of sectors in FAT area */
	fs->fatbase = basesect += LD_WORD(&fs->win[14]);	/* FAT start sector (lba) */
	basesect += fatsize;		/* Next sector of FAT area (lba) */
	fs->sects_clust = fs->win[13];						/* Number of sectors per cluster */
	fs->n_rootdir = LD_WORD(&fs->win[17]);				/* Nmuber of root directory entries */
	totalsect = LD_WORD(&fs->win[19]);					/* Number of sectors on the file system */
	if (!totalsect) totalsect = LD_DWORD(&fs->win[32]);
	fs->max_clust = maxclust = (totalsect				/* Last cluster# + 1 */
		- LD_WORD(&fs->win[14]) - fatsize - fs->n_rootdir / 16
		) / fs->sects_clust + 2;
	fmt = FS_FAT12;										/* Determins the FAT type */
	if (maxclust >= 0xFF7) fmt = FS_FAT16;
#if _FAT32 == 0
	if (maxclust >= 0xFFF7) return FR_NO_FILESYSTEM;
#else
	if (maxclust >= 0xFFF7) fmt = FS_FAT32;
	if (fmt == FS_FAT32)
		fs->dirbase = LD_DWORD(&fs->win[44]);			/* Root directory start cluster */
	else
#endif
		fs->dirbase = basesect;							/* Root directory start sector (lba) */
	fs->database = basesect + fs->n_rootdir / 16;		/* Data start sector (lba) */

	fs->fs_type = fmt;									/* FAT type */
	fs->id = ++fsid;									/* File system mount ID */

	return FR_OK;
}




/*-----------------------------------------------------------------------*/
/* Check if the file/dir object is valid or not                          */
/*-----------------------------------------------------------------------*/

static
FRESULT validate (		/* FR_OK(0): The id is valid, !=0: Not valid */
	const FATFS *fs,	/* Pointer to the file system object */
	WORD id				/* id member of the target object to be checked */
)
{
	if (!fs || (WORD)~fs->id != id)
		return FR_INVALID_OBJECT;
	if (disk_status(0) & STA_NOINIT)
		return FR_NOT_READY;

	return FR_OK;
}




/*--------------------------------------------------------------------------

   Public Functions

--------------------------------------------------------------------------*/


/*-----------------------------------------------------------------------*/
/* Mount/Unmount a Locical Drive                                         */
/*-----------------------------------------------------------------------*/

FRESULT f_mount (
	BYTE drv,		/* Logical drive number to be mounted/unmounted */
	FATFS *fs		/* Pointer to new file system object (NULL for unmount)*/
)
{
	FATFS *fsobj;


	if (drv) return FR_INVALID_DRIVE;
	fsobj = FatFs;
	FatFs = fs;
	if (fsobj) memset(fsobj, 0, sizeof(FATFS));
	if (fs) memset(fs, 0, sizeof(FATFS));

	return FR_OK;
}




/*-----------------------------------------------------------------------*/
/* Open or Create a File                                                 */
/*-----------------------------------------------------------------------*/

FRESULT f_open (
	FIL *fp,			/* Pointer to the blank file object */
	const char *path,	/* Pointer to the file name */
	BYTE mode			/* Access mode and file open mode flags */
)
{
	FRESULT res;
	BYTE *dir;
	DIR dirobj;
	char fn[8+3+1];
	FATFS *fs = FatFs;


#if _FS_READONLY == 0
	res = auto_mount(&path, mode & (FA_WRITE|FA_CREATE_ALWAYS|FA_OPEN_ALWAYS));
#else
	res = auto_mount(&path, 0);
#endif
	if (res != FR_OK) return res;

	/* Trace the file path */
	res = trace_path(&dirobj, fn, path, &dir);	/* Trace the file path */

#if _FS_READONLY == 0
	/* Create or Open a File */
	if (mode & (FA_CREATE_ALWAYS|FA_OPEN_ALWAYS)) {
		CLUST ps, rs;
		DWORD tm;
		if (res != FR_OK) {		/* No file, create new */
			mode |= FA_CREATE_ALWAYS;
			if (res != FR_NO_FILE) return res;
			dir = reserve_direntry(&dirobj);	/* Reserve a directory entry */
			if (dir == NULL) return FR_DENIED;
			memset(dir, 0, 32);		/* Initialize the new entry */
			memcpy(dir, fn, 8+3);
			*(dir+12) = fn[11];
		} else {				/* Any object is already existing */
			if (dir == NULL || (*(dir+11) & (AM_RDO|AM_DIR)))	/* Could not overwrite (R/O or DIR) */
				return FR_DENIED;
			if (mode & FA_CREATE_ALWAYS) {	/* Resize it to zero */
#if _FAT32 != 0
				rs = ((DWORD)LD_WORD(dir+20) << 16) | LD_WORD(dir+26);
				ST_WORD(dir+20, 0);
#else
				rs = LD_WORD(dir+26);
#endif
				ST_WORD(dir+26, 0);						/* cluster = 0 */
				ST_DWORD(dir+28, 0);					/* size = 0 */
				fs->winflag = 1;
				ps = fs->winsect;						/* Remove the cluster chain */
				if (!remove_chain(rs) || !move_window(ps))
					return FR_RW_ERROR;
			}
		}
		if (mode & FA_CREATE_ALWAYS) {
			*(dir+11) = AM_ARC;
			tm = get_fattime();
			ST_DWORD(dir+14, tm);	/* Created time */
			ST_DWORD(dir+22, tm);	/* Updated time */
			fs->winflag = 1;
		}
	}
	/* Open a File */
	else {
#endif /* _FS_READONLY */
		if (res != FR_OK) return res;		/* Trace failed */
		if (dir == NULL || (*(dir+11) & AM_DIR))	/* It is a directory */
			return FR_NO_FILE;
#if _FS_READONLY == 0
		if ((mode & FA_WRITE) && (*(dir+11) & AM_RDO)) /* R/O violation */
			return FR_DENIED;
	}
#endif

#if _FS_READONLY == 0
	fp->flag = mode & (FA_WRITE|FA_READ);
	fp->dir_sect = fs->winsect;			/* Pointer to the directory entry */
	fp->dir_ptr = dir;
#else
	fp->flag = mode & FA_READ;
#endif
	fp->org_clust =	LD_WORD(dir+26);	/* File start cluster */
	fp->fsize = LD_DWORD(dir+28);		/* File size */
	fp->fptr = 0;						/* File ptr */
	fp->sect_clust = 1;					/* Sector counter */
	fp->fs = fs; fp->id = ~fs->id;		/* Owner file system object of the file */
	return FR_OK;
}




/*-----------------------------------------------------------------------*/
/* Read File                                                             */
/*-----------------------------------------------------------------------*/

FRESULT f_read (
	FIL *fp, 		/* Pointer to the file object */
	void *buff,		/* Pointer to data buffer */
	WORD btr,		/* Number of bytes to read */
	WORD *br		/* Pointer to number of bytes read */
)
{
	DWORD sect, remain;
	WORD rcnt;
	CLUST clust;
	BYTE cc, *rbuff = buff;
	FRESULT res;
	FATFS *fs = fp->fs;


	*br = 0;
	res = validate(fs, fp->id);
	if (res) return res;
	if (fp->flag & FA__ERROR) return FR_RW_ERROR;	/* Check error flag */
	if (!(fp->flag & FA_READ)) return FR_DENIED;	/* Check access mode */
	remain = fp->fsize - fp->fptr;
	if (btr > remain) btr = (WORD)remain;			/* Truncate read count by number of bytes left */

	for ( ;  btr;									/* Repeat until all data transferred */
		rbuff += rcnt, fp->fptr += rcnt, *br += rcnt, btr -= rcnt) {
		if ((fp->fptr % 512) == 0) {				/* On the sector boundary */
			if (--(fp->sect_clust)) {				/* Decrement left sector counter */
				sect = fp->curr_sect + 1;			/* Get current sector */
			} else {								/* On the cluster boundary, get next cluster */
				clust = (fp->fptr == 0) ? 
					fp->org_clust : get_cluster(fp->curr_clust);
				if (clust < 2 || clust >= fs->max_clust)
					goto fr_error;
				fp->curr_clust = clust;				/* Current cluster */
				sect = clust2sect(clust);			/* Get current sector */
				fp->sect_clust = fs->sects_clust;	/* Re-initialize the left sector counter */
			}
			fp->curr_sect = sect;					/* Update current sector */
			cc = btr / 512;							/* When left bytes >= 512, */
			if (cc) {								/* Read maximum contiguous sectors directly */
				if (cc > fp->sect_clust) cc = fp->sect_clust;
				if (disk_read(0, rbuff, sect, cc) != RES_OK)
					goto fr_error;
				fp->sect_clust -= cc - 1;
				fp->curr_sect += cc - 1;
				rcnt = cc * 512; continue;
			}
		}
		if (!move_window(fp->curr_sect)) goto fr_error;	/* Move sector window */
		rcnt = 512 - (WORD)(fp->fptr % 512);			/* Copy fractional bytes from sector window */
		if (rcnt > btr) rcnt = btr;
		memcpy(rbuff, &fs->win[fp->fptr % 512], rcnt);
	}

	return FR_OK;

fr_error:	/* Abort this function due to an unrecoverable error */
	fp->flag |= FA__ERROR;
	return FR_RW_ERROR;
}




/*-----------------------------------------------------------------------*/
/* Write File                                                            */
/*-----------------------------------------------------------------------*/

#if _FS_READONLY == 0
FRESULT f_write (
	FIL *fp,			/* Pointer to the file object */
	const void *buff,	/* Pointer to the data to be written */
	WORD btw,			/* Number of bytes to write */
	WORD *bw			/* Pointer to number of bytes written */
)
{
	DWORD sect;
	WORD wcnt;
	CLUST clust;
	BYTE cc;
	FRESULT res;
	const BYTE *wbuff = buff;
	FATFS *fs = fp->fs;


	*bw = 0;
	res = validate(fs, fp->id);
	if (res) return res;
	if (fp->flag & FA__ERROR) return FR_RW_ERROR;	/* Check error flag */
	if (!(fp->flag & FA_WRITE)) return FR_DENIED;	/* Check access mode */
	if (fp->fsize + btw < fp->fsize) btw = 0;		/* File size cannot reach 4GB */

	for ( ;  btw;									/* Repeat until all data transferred */
		wbuff += wcnt, fp->fptr += wcnt, *bw += wcnt, btw -= wcnt) {
		if ((fp->fptr % 512) == 0) {				/* On the sector boundary */
			if (--(fp->sect_clust)) {				/* Decrement left sector counter */
				sect = fp->curr_sect + 1;			/* Get current sector */
			} else {								/* On the cluster boundary, get next cluster */
				if (fp->fptr == 0) {				/* Is top of the file */
					clust = fp->org_clust;
					if (clust == 0)					/* No cluster is created yet */
						fp->org_clust = clust = create_chain(0);	/* Create a new cluster chain */
				} else {							/* Middle or end of file */
					clust = create_chain(fp->curr_clust);			/* Trace or streach cluster chain */
				}
				if (clust < 2 || clust >= fs->max_clust) break;
				fp->curr_clust = clust;				/* Current cluster */
				sect = clust2sect(clust);			/* Get current sector */
				fp->sect_clust = fs->sects_clust;	/* Re-initialize the left sector counter */
			}
			fp->curr_sect = sect;					/* Update current sector */
			cc = btw / 512;							/* When left bytes >= 512, */
			if (cc) {								/* Write maximum contiguous sectors directly */
				if (cc > fp->sect_clust) cc = fp->sect_clust;
				if (disk_write(0, wbuff, sect, cc) != RES_OK)
					goto fw_error;
				fp->sect_clust -= cc - 1;
				fp->curr_sect += cc - 1;
				wcnt = cc * 512; continue;
			}
			if (fp->fptr >= fp->fsize) {			/* Flush R/W window if needed */
				if (!move_window(0)) goto fw_error;
				fs->winsect = fp->curr_sect;
			}
		}
		if (!move_window(fp->curr_sect))			/* Move sector window */
			goto fw_error;
		wcnt = 512 - (WORD)(fp->fptr % 512);			/* Copy fractional bytes bytes to sector window */
		if (wcnt > btw) wcnt = btw;
		memcpy(&fs->win[fp->fptr % 512], wbuff, wcnt);
		fs->winflag = 1;
	}

	if (fp->fptr > fp->fsize) fp->fsize = fp->fptr;	/* Update file size if needed */
	fp->flag |= FA__WRITTEN;						/* Set file changed flag */
	return FR_OK;

fw_error:	/* Abort this function due to an unrecoverable error */
	fp->flag |= FA__ERROR;
	return FR_RW_ERROR;
}
#endif /* _FS_READONLY */




/*-----------------------------------------------------------------------*/
/* Seek File Pointer                                                     */
/*-----------------------------------------------------------------------*/

FRESULT f_lseek (
	FIL *fp,		/* Pointer to the file object */
	DWORD ofs		/* File pointer from top of file */
)
{
	CLUST clust;