PROJECT: SINGLIX Operating System Issue: 3 Revision: 12 Date: 19/05/2009 OWNER: ERDOĞAN TAN / Istanbul / Turkiye
DIRECTORY DESCRIPTION TABLE Format of SINGLIX FS1, FS2 file systems
Offset	Item	DATA	Type	Size	Description of Item
0	DDT Sign	‘DDT’	Char	3 byte	TR-SINGLIX Directory Description Table
3	FS DDT Version	XXh	Byte	1 byte	Must be 0 for Current/This DDT Version
4	Sector Size	XXXXh	Word	2 byte	Bytes per Sector (FS1=512, FS2=2048)
6	DDT Number	XXXXh	Word	2 byte	DDT (Sequence) Number of This Dir.
8	Directory Number	XXXXXXXXh	Dword	4 byte	The 1st DDT Address of This Dir. (LBA)
12	Next DDT Number	XXXXXXXXh	Dword	4 byte	DDT address of the next section (LBA)
16	Sector Count	XXXXXXXXh	Dword	4 byte	Number of Sectors in this section
20	Parent Dir Number	XXXXXXXXh	Dword	4 byte	The Parent DDT Addr. of This Dir. (LBA)
24	Parent Dir Serial	XXXXXXXXh	Dword	4 byte	The Parent Dir’s Serial No. (Tick Count)
28	Directory Serial	XXXXXXXXh	Dword	4 byte	Directory Serial Number (Tick Count)
32	Entry Size	04h	Byte	1 byte	Directory Entry Size (= 4 bytes)
33	Reserved	XXh	Byte	1 byte	Reserved (Sub Directory Level)
34	Directory Type	XXXXh	Word	2 byte	Major, Minor Type Descriptor of This Dir.
36	CheckSum	XXh	Byte	1 byte	DirectoryName CheckSum
37	Attributes	XXh	Byte	1 byte	Permissions for Owner, Group, Others
38*	Owner Code	XXXXXXXXh	Dword	4 byte	Owner Description Table Address (LBA)
42*	Group Code	XXXXXXXXh	Dword	4 byte	Group Description Table Address (LBA)
46	Country	XXh	Byte	1 byte	Language, Date, Text Format (default = 0)
47	Time Zone	XXh	Byte	1 byte	-11 to +12  (GMT = 0, default = 0)
48	Creating year	XXXXXXXXh	Word	2 byte	Year in Binary Coded Decimal (BCD)
50	Creating Month	XXh	Byte	1 byte	Month in Binary Coded Decimal (BCD)
51	Creating Day	XXh	Byte	1 byte	Day in Binary Coded Decimal (BCD)
52	Creating Hour	XXXXh (CCYY)	Byte	1 byte	Hour in Binary Coded Decimal (BCD)
53	Creating Minute	XXh	Byte	1 byte	Minute in Binary Coded Decimal (BCD)
54	Creating Second	XXh	Byte	1 byte	Second in Binary Coded Decimal (BCD)
55	C. Time Mode	XXh	Byte	1 byte	0 = Standard Time, 1 = Daylight Saving
56	Last Modif. Date	XXXXXXXXh	Dword	4 byte	The Last Modification/Write Date (BCD)
60	Last Modif. Time	XXXXXXh	Byte	3 byte	The Last Modification/Write Time (BCD)
63	L. M. Time Mode	XXh	Byte	1 byte	0= Standard, 1 = Daylight Saving Time
64	Directory Name	<FileName>	Char	64 byte	64 byte full or zero terminated Dir. Name
128	Dir. Description	Text	Char	128 byte	Directory Description Text
256	Reserved	?	Byte	256 byte	256 byte Reserved/Optional Data Field
512**	Reserved	?	Byte	1536 byte	Optional/Reserved Area for FS2 Files
* Used by TR-MULTIX (Multi User, Multi Tasking) Operating System, only! ** 1536 byte extra description for 2048 bytes per sector File System (FS2), only ! Optional ! NOTE: Erased/Deleted Dir. Sign: ‘DDE’, ‘E’ at offset 2 instead of ‘T’. (Parent Dir’s Entry: FFFFFFFFh is erased entry, 0 is end of directory entries.) Directory entries are the 1st FDT or DDT addresses of files or child/sub directories. (32 bit sector offset number which is > 0 and < FFFFFFFFh) Parent Dir. Serial used for that purpose: When a dir or file is deleted, it will be removed from parent dir entries by replacing child directory or file number to FFFFFFFFh = deleted entry sign. And, it will be located in UNDELETE Directory as a new deleted file entry. When user want to undelete this file/dir, if parent dir serial number same with in the parent directory descriptor table (as number) declared in child dir decriptor table, the deleted directory or file will be restored in the parent directory. Directory serial number is just a tick count which always different by the computer’s timer ticks. (as like as volume serial number.) For the First DDT (DDT0) of every file, this 1 sector DDT structure is completely valid and used. If a file has multiple DDTs (has more than one data section on the disk), except DDT 0, next and other DDTs use or carry the first 20 bytes of DDT structure as valid. Remain items are not used or not valid. So, the first DDT (FileNumber, Offset 8) is only reference to full FDT structure for file recovery or reverse/trace procedures. (Offset 8 points the DDT 0 address , Offset 6 has the current DDT seguence number.) By using only DDT0 parameters (except the first 20 bytes of DDTs), all of DDT contents after directory create, move, update (directory name, path and size changements etc.) procedures are kept true/correct for all DDTs. DDT1 and others must have valid 20 bytes on to Offset 20, then, must have ZERO bytes.(If all directory entries are in a single data section, only DDT0 is used and Offset 12 of DDT0 has ZERO.) ATTRIBUTES byte: Bit 0 = Owner’s Write Permission (1= Yes, 0= No) [ 0 => Read only directory ] Bit 1 = Owner’s Execute Permission (Always 0) Bit 2 = Group User’s Read Permission (1=Yes, 0= No) [ 0 => This dir. is not visible except the owner ] Bit 3 = Group User’s Write Permission (1=Yes, 0= No) [ Can be YES if Bit 0 is YES ] Bit 4 = Group User’s Execute Permission (Always 0) Bit 5 = Other User’s Read Permission (1=Yes, 0= No) [ 0 => This dir. is not visible except the group ] Bit 6 = Other User’s Write Permission (1=Yes, 0= No) [ Can be YES if Bit 0 and Bit 3 are YES ] Bit 7 = Other User’s Execute Permission (Always 0)