ff.c

S64和VS1003的MP3播放实现的源代码/

	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 & (S_SIZ - 1)) == 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(fs, fp->curr_clust);
				if (clust < 2 || clust >= fs->max_clust)
					goto fr_error;
				fp->curr_clust = clust;				/* Current cluster */
				sect = clust2sect(fs, clust);		/* Get current sector */
				fp->sect_clust = fs->sects_clust;	/* Re-initialize the left sector counter */
			}
#if _FS_READONLY == 0
			if (fp->flag & FA__DIRTY) {				/* Flush file I/O buffer if needed */
				if (disk_write(fs->drive, fp->buffer, fp->curr_sect, 1) != RES_OK)
					goto fr_error;
				fp->flag &= ~FA__DIRTY;
			}
#endif
			fp->curr_sect = sect;					/* Update current sector */
			cc = btr / S_SIZ;						/* When left bytes >= S_SIZ, */
			if (cc) {								/* Read maximum contiguous sectors directly */
				if (cc > fp->sect_clust) cc = fp->sect_clust;
				if (disk_read(fs->drive, rbuff, sect, cc) != RES_OK)
					goto fr_error;
				fp->sect_clust -= cc - 1;
				fp->curr_sect += cc - 1;
				rcnt = cc * S_SIZ; continue;
			}
			if (disk_read(fs->drive, fp->buffer, sect, 1) != RES_OK)	/* Load the sector into file I/O buffer */
				goto fr_error;
		}
		rcnt = S_SIZ - ((WORD)fp->fptr & (S_SIZ - 1));				/* Copy fractional bytes from file I/O buffer */
		if (rcnt > btr) rcnt = btr;
		memcpy(rbuff, &fp->buffer[fp->fptr & (S_SIZ - 1)], rcnt);
	}

	return FR_OK;

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




#if _FS_READONLY == 0
/*-----------------------------------------------------------------------*/
/* Write File                                                            */
/*-----------------------------------------------------------------------*/

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 clust, sect;
	WORD wcnt;
	BYTE cc;
	FRESULT res;
	const BYTE *wbuff = buff;
	FATFS *fs = fp->fs;


	*bw = 0;
	res = validate(fs, fp->id);						/* Check validity of the object */
	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) return FR_OK;	/* File size cannot reach 4GB */

	for ( ;  btw;									/* Repeat until all data transferred */
		wbuff += wcnt, fp->fptr += wcnt, *bw += wcnt, btw -= wcnt) {
		if ((fp->fptr & (S_SIZ - 1)) == 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(fs, 0);	/* Create a new cluster chain */
				} else {							/* Middle or end of file */
					clust = create_chain(fs, fp->curr_clust);			/* Trace or streach cluster chain */
				}
				if (clust == 0) break;				/* Disk full */
				if (clust == 1 || clust >= fs->max_clust) goto fw_error;
				fp->curr_clust = clust;				/* Current cluster */
				sect = clust2sect(fs, clust);		/* Get current sector */
				fp->sect_clust = fs->sects_clust;	/* Re-initialize the left sector counter */
			}
			if (fp->flag & FA__DIRTY) {				/* Flush file I/O buffer if needed */
				if (disk_write(fs->drive, fp->buffer, fp->curr_sect, 1) != RES_OK)
					goto fw_error;
				fp->flag &= ~FA__DIRTY;
			}
			fp->curr_sect = sect;					/* Update current sector */
			cc = btw / S_SIZ;						/* When left bytes >= S_SIZ, */
			if (cc) {								/* Write maximum contiguous sectors directly */
				if (cc > fp->sect_clust) cc = fp->sect_clust;
				if (disk_write(fs->drive, wbuff, sect, cc) != RES_OK)
					goto fw_error;
				fp->sect_clust -= cc - 1;
				fp->curr_sect += cc - 1;
				wcnt = cc * S_SIZ; continue;
			}
			if (fp->fptr < fp->fsize &&  			/* Fill sector buffer with file data if needed */
				disk_read(fs->drive, fp->buffer, sect, 1) != RES_OK)
					goto fw_error;
		}
		wcnt = S_SIZ - ((WORD)fp->fptr & (S_SIZ - 1));	/* Copy fractional bytes to file I/O buffer */
		if (wcnt > btw) wcnt = btw;
		memcpy(&fp->buffer[fp->fptr & (S_SIZ - 1)], wbuff, wcnt);
		fp->flag |= FA__DIRTY;
	}

	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 file due to an unrecoverable error */
	fp->flag |= FA__ERROR;
	return FR_RW_ERROR;
}




/*-----------------------------------------------------------------------*/
/* Synchronize between File and Disk                                     */
/*-----------------------------------------------------------------------*/

FRESULT f_sync (
	FIL *fp		/* Pointer to the file object */
)
{
	DWORD tim;
	BYTE *dir;
	FRESULT res;
	FATFS *fs = fp->fs;


	res = validate(fs, fp->id);			/* Check validity of the object */
	if (res == FR_OK) {
		if (fp->flag & FA__WRITTEN) {	/* Has the file been written? */
			/* Write back data buffer if needed */
			if (fp->flag & FA__DIRTY) {
				if (disk_write(fs->drive, fp->buffer, fp->curr_sect, 1) != RES_OK)
					return FR_RW_ERROR;
				fp->flag &= ~FA__DIRTY;
			}
			/* Update the directory entry */
			if (!move_window(fs, fp->dir_sect))
				return FR_RW_ERROR;
			dir = fp->dir_ptr;
			dir[DIR_Attr] |= AM_ARC;						/* Set archive bit */
			ST_DWORD(&dir[DIR_FileSize], fp->fsize);		/* Update file size */
			ST_WORD(&dir[DIR_FstClusLO], fp->org_clust);	/* Update start cluster */
			ST_WORD(&dir[DIR_FstClusHI], fp->org_clust >> 16);
			tim = get_fattime();					/* Updated time */
			ST_DWORD(&dir[DIR_WrtTime], tim);
			fp->flag &= ~FA__WRITTEN;
			res = sync(fs);
		}
	}
	return res;
}

#endif /* _FS_READONLY == 0 */




/*-----------------------------------------------------------------------*/
/* Close File                                                            */
/*-----------------------------------------------------------------------*/

FRESULT f_close (
	FIL *fp		/* Pointer to the file object to be closed */
)
{
	FRESULT res;


#if _FS_READONLY == 0
	res = f_sync(fp);
#else
	res = validate(fp->fs, fp->id);
#endif
	if (res == FR_OK)
		fp->fs = NULL;
	return res;
}




#if _FS_MINIMIZE <= 2
/*-----------------------------------------------------------------------*/
/* Seek File R/W Pointer                                                 */
/*-----------------------------------------------------------------------*/

FRESULT f_lseek (
	FIL *fp,		/* Pointer to the file object */
	DWORD ofs		/* File pointer from top of file */
)
{
	DWORD clust, csize;
	BYTE csect;
	FRESULT res;
	FATFS *fs = fp->fs;


	res = validate(fs, fp->id);			/* Check validity of the object */
	if (res) return res;
	if (fp->flag & FA__ERROR) return FR_RW_ERROR;
#if _FS_READONLY == 0
	if (fp->flag & FA__DIRTY) {			/* Write-back dirty buffer if needed */
		if (disk_write(fs->drive, fp->buffer, fp->curr_sect, 1) != RES_OK)
			goto fk_error;
		fp->flag &= ~FA__DIRTY;
	}
	if (ofs > fp->fsize && !(fp->flag & FA_WRITE))
#else
	if (ofs > fp->fsize)
#endif
		ofs = fp->fsize;
	fp->fptr = 0; fp->sect_clust = 1;		/* Set file R/W pointer to top of the file */

	/* Move file R/W pointer if needed */
	if (ofs) {
		clust = fp->org_clust;	/* Get start cluster */
#if _FS_READONLY == 0
		if (!clust) {			/* If the file does not have a cluster chain, create new cluster chain */
			clust = create_chain(fs, 0);
			if (clust == 1) goto fk_error;
			fp->org_clust = fp->curr_clust = clust;
		}
#endif
		if (clust) {			/* If the file has a cluster chain, it can be followed */
			csize = (DWORD)fs->sects_clust * S_SIZ;		/* Cluster size in unit of byte */
			while (ofs > csize) {						/* Skip leading clusters */
#if _FS_READONLY == 0
				if (fp->flag & FA_WRITE)					/* Check if in write mode or not */
					clust = create_chain(fs, clust);		/* Force streached if in write mode */
				else
#endif
					clust = get_cluster(fs, clust);			/* Only follow cluster chain if not in write mode */
				if (clust == 0) {							/* Stop if could not follow the cluster chain */
					ofs = csize;
					break;
				}
				if (clust == 1 || clust >= fs->max_clust) goto fk_error; /* Abort when any error occured */
				fp->curr_clust = clust;						/* Update current cluster and R/W pointer */
				fp->fptr += csize;
				ofs -= csize;
			}
			csect = (BYTE)((ofs - 1) / S_SIZ);			/* Sector offset in the cluster */
			fp->curr_sect = clust2sect(fs, clust) + csect;	/* Get current cluster */
			if ((ofs & (S_SIZ - 1)) &&					/* Load current sector if needed */
				disk_read(fs->drive, fp->buffer, fp->curr_sect, 1) != RES_OK)
				goto fk_error;
			fp->sect_clust = fs->sects_clust - csect;	/* Left sector counter in the cluster */
			fp->fptr += ofs;							/* Update file R/W pointer */
		}
	}
#if _FS_READONLY == 0
	if ((fp->flag & FA_WRITE) && fp->fptr > fp->fsize) {	/* Set updated flag if in write mode */
		fp->fsize = fp->fptr;
		fp->flag |= FA__WRITTEN;
	}
#endif

	return FR_OK;

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




#if _FS_MINIMIZE <= 1
/*-----------------------------------------------------------------------*/
/* Create a directroy object                                             */
/*-----------------------------------------------------------------------*/

FRESULT f_opendir (
	DIR *dirobj,		/* Pointer to directory object to create */
	const char *path	/* Pointer to the directory path */
)
{
	BYTE *dir;
	char fn[8+3+1];
	FRESULT res;
	FATFS *fs;


	res = auto_mount(&path, &fs, 0);
	if (res != FR_OK) return res;
	dirobj->fs = fs;

	res = trace_path(dirobj, fn, path, &dir);	/* Trace the directory path */
	if (res == FR_OK) {						/* Trace completed */
		if (dir != NULL) {					/* It is not the root dir */
			if (dir[DIR_Attr] & AM_DIR) {		/* The entry is a directory */
				dirobj->clust = ((DWORD)LD_WORD(&dir[DIR_FstClusHI]) << 16) | LD_WORD(&dir[DIR_FstClusLO]);
				dirobj->sect = clust2sect(fs, dirobj->clust);
				dirobj->index = 2;
			} else {						/* The entry is not a directory */
				res = FR_NO_FILE;
			}
		}
		dirobj->id = fs->id;
	}
	return res;
}




/*-----------------------------------------------------------------------*/
/* Read Directory Entry in Sequense                                      */
/*-----------------------------------------------------------------------*/

FRESULT f_readdir (
	DIR *dirobj,		/* Pointer to the directory object */
	FILINFO *finfo		/* Pointer to file information to return */
)
{
	BYTE *dir, c, res;
	FATFS *fs = dirobj->fs;


	res = validate(fs, dirobj->id);			/* Check validity of the object */
	if (res) return res;

	finfo->fname[0] = 0;
	while (dirobj->sect) {
		if (!move_window(fs, dirobj->sect))
			return FR_RW_ERROR;
		dir = &fs->win[(dirobj->index & ((S_SIZ - 1) >> 5)) * 32];	/* pointer to the directory entry */
		c = *dir;
		if (c == 0) break;								/* Has it reached to end of dir? */
		if (c != 0xE5 && !(dir[DIR_Attr] & AM_VOL))		/* Is it a valid entry? */
			get_fileinfo(finfo, dir);
		if (!next_dir_entry(dirobj)) dirobj->sect = 0;	/* Next entry */
		if (finfo->fname[0]) break;						/* Found valid entry */
	}

	return FR_OK;
}




#if _FS_MINIMIZE == 0
/*-----------------------------------------------------------------------*/
/* Get File Status                                                       */
/*-----------------------------------------------------------------------*/

FRESULT f_stat (
	const char *path,	/* Pointer to the file path */
	FILINFO *finfo		/* Pointer to file information to return */
)
{
	BYTE *dir;
	char fn[8+3+1];
	FRESULT res;
	DIR dirobj;
	FATFS *fs;


	res = auto_mount(&path, &fs, 0);
	if (res != FR_OK) return res;
	dirobj.fs = fs;

	res = trace_path(&dirobj, fn, path, &dir);	/* Trace the file path */
	if (res == FR_OK) {							/* Trace completed */
		if (dir)	/* Found an object */
			get_fileinfo(finfo, dir);
		else		/* It is root dir */
			res = FR_INVALID_NAME;
	}

	return res;
}



#if _FS_READONLY == 0
/*-----------------------------------------------------------------------*/
/* Get Number of Free Clusters                                           */
/*-----------------------------------------------------------------------*/

FRESULT f_getfree (
	const char *drv,	/* Logical drive number */
	DWORD *nclust,		/* Pointer to the double word to return number of free clusters */
	FATFS **fatfs		/* Pointer to pointer to the file system object to return */
)
{
	DWORD n, clust, sect;
	BYTE fat, f, *p;
	FRESULT res;
	FATFS *fs;


	/* Get drive number */
	res = auto_mount(&drv, &fs, 0);
	if (res != FR_OK) return res;
	*fatfs = fs;

	/* Count number of free clusters */
	fat = fs->fs_type;
	n = 0;
	if (fat == FS_FAT12) {
		clust = 2;
		do {
			if ((WORD)get_cluster(fs, clust) == 0) n++;
		} while (++clust < fs->max_clust);
	} else {