uflashfs.c File Reference

UFLASH File System. More...

#include <fs/fs.h>
#include <sys/nutdebug.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <string.h>
#include <errno.h>
#include <dirent.h>
#include <dev/spi_at45dib.h>
#include <fs/uflashfs.h>

Include dependency graph for uflashfs.c:

Go to the source code of this file.

Data Structures
struct	_BLOCK_USAGE
	Internal block usage cache structure. More...
struct	_BLOCKHEAD
	UFLASH block header. More...
struct	_BLOCKFOOT
	UFLASH block footer. More...
struct	_ENTRYHEAD
struct	_UFLASHENTRY
	File system entry descriptor. More...
struct	_UFLASHVOLUME
	Volume info structure. More...
struct	_UFLASHFIND
	Entry search structure. More...
Defines
#define	UFLASH_MAX_BLOCKS   8192
	Max. number of blocks per file system.
#define	UFLASH_BLOCK_UNITS   4
	Number of units per block.
#define	UFLASH_ENTRIES   128
	Number of file system entries.
#define	UFLASH_USAGE_CACHE   32
	Size of the least used buffer.
#define	UFLASH_MAX_PATH   0
	Maximum lenght of a full absolute path.
#define	UFLASH_BLOCK_INVALID   ((blknum_t)-1)
#define	UFLASH_VOLF_FIXED   0x80
Typedefs
typedef uint16_t	blknum_t
typedef uint_fast16_t	blknum_fast_t
typedef struct _BLOCK_USAGE	BLOCK_USAGE
	Internal block usage cache structure.
typedef struct _BLOCKHEAD	BLOCKHEAD
	UFLASH block header.
typedef struct _BLOCKFOOT	BLOCKFOOT
	UFLASH block footer.
typedef struct _ENTRYHEAD	ENTRYHEAD
typedef struct _UFLASHENTRY	UFLASHENTRY
	File system entry descriptor.
typedef struct _UFLASHVOLUME	UFLASHVOLUME
	Volume info structure type.
typedef struct _UFLASHFIND	UFLASHFIND
	Entry search structure.
Functions
int	UFlashAttach (NUTDEVICE *dev, NUTSERIALFLASH *sfi, NUTSPIBUS *bus)
	Attach an UFLASH file system to a serial flash device.
void	UFlashDetach (NUTDEVICE *dev)
	Detach an UFLASH file system from a serial flash device.
int	UFlashFormat (NUTDEVICE *dev, NUTSERIALFLASH *sfi, NUTSPIBUS *bus)
	Format an UFLASH volume.
Variables
NUTDEVICE	devUFlash0
	UFLASH0 file system device.
NUTDEVICE	devUFlash1
	UFLASH1 file system device.

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Detailed Description

UFLASH File System.

The UFLASH file system has been specifically designed for serial flash memory chips used on tiny embedded systems.

Such memory chips do not allow to program single bytes. Instead, only full pages can be programmed. On the other hand, these chips provide one or two integrated RAM buffers. They allow to modify single bytes without transfering full pages between the memory chip and the microcontroller's RAM.

Although no mechanism has been implemented to replace worn out pages, the file system maintains a very well balanced wear levelling. This includes regular movement of static files.

Furthermore, previously unfinished write accesses are automatically detected and reverted when mounting a volume. However, this features still needs to be tested more thoroughly.

Note, that directories do not really exist in the UFLASH file system. They are mimicked in a limited way. When scanning a directory, all subdirectories will appear again for each file they contain.

 * $Id$
 * 

Definition in file uflashfs.c.