TOCBLOCK - Technical

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The TOCBLOCK is 512 bytes long. There are two identical copies of this information (each has an adjacent previous copy). One of the two contiguous pair is located at (Private Region Start LBA + 1) and the other is located at (Private Region Start LBA + Size LBA - 3).

The sizes are in sectors and the starts are relative to the start of the private region.

At the moment there are two regions, config and log.


Offset Size Description
0x00 8 TOCBLOCK Magic number
0x08 4 Checksum (a)
0x0C 8 Update Sequence Number (b)
0x14 16 Zeros
0x24 34 TOC Region 0
0x46 34 TOC Region 1
0x68 34 ...

TOC Region Layout

Offset Size Description
0x00 8 Region Name
0x08 2 Region Flags (see below)
0x0A 8 Region Start LBA (relative to Private Region Start)
0x12 8 Region Size LBA
0x1A 2
Unknown (always 00 06)
0x1C 2 Copy Number (always 00 01)
0x1E 4 Zeros

Region Flags:

Flag Description
0x01 not exist
0x02 new
0x04 delete
0x08 disabled


(a) Sum of all the bytes in the sector excluding the 4 bytes of the checksum field
(b) The most recent TOCBlock has this value in sync with the Private Header's Update Sequence Number.
(c) you can tell if a region is present by checking if the first byte (the first character of Name) is not null

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