Summary of FAT file system 3

Eight, long file names

Long file names are on the original FAT system introduced on only supports short file name system, like the long file name does not exist. To achieve this goal, the long file name by introducing a new character attributes (Attribute) in the original directory entry can be achieved.

ATTR_LONG_NAME = ATTR_READ_ONLY |

ATTR_HIDDEN |

ATTR_SYSTEM |

ATTR_VOLUME_ID

Determine whether a directory entry for the long file name, to MASK achieved through the following:

ATTR_LONG_NAME_MASK = ATTR_READ_ONLY |

ATTR_HIDDEN |

ATTR_SYSTEM |

ATTR_VOLUME_ID |

ATTR_DIRECTORY |

ATTR_ARCHIVE

Long filename directory entry data structure is as follows:

Name	Offset	Size	Description
	(Byte)	(Bytes)
LDIR_Ord	0x00	1	The number in the file name of the leader.
			If the first 6 bit is 1 (Mask with 0x40), illustrate this
			This is the last leader of the file name.Each group of effective long file
			Name must have this flag.

LDIR_Name1	0x01	10	1-5 characters long file names
LDIR_Attr	0x0B	1	Properties words - must be 0x0F (ATTR_LONG_NAME)
LDIR_Type	0x0C	1	If it is 0, it means that the directory entry is part of the long file names.
			Non-zero value for the retention settings.
LDIR_Chksum	0x0D	1	Corresponding short file name checksum (Checksum)
LDIR_Name2	0x0E	12	6-11 characters long file names
LDIR_FstClusLO	0x1A	2	Must be ZERO. This is an artifact of the
			FAT "first cluster" and must be zero for
			Compatibility with existing disk
			utilities. It's Meaningless in the
			context of a long dir entry.
LDIR_Name3	0x1C	4	12-13 characters long file names

Long file names using Unicode character encoding.

Checksum algorithms, implemented in C language as follows:

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