uflashfs.c File Reference

UFLASH File System. More...

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Defines

#define UFLASH_BLOCK_UNITS   4
 Max. number of blocks per file system.
#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 uint8_t blknum_t
typedef uint_fast8_t blknum_fast_t

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.

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.

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Definition in file uflashfs.c.


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