libaaruformat/docs/spec/blocks/track_layout.adoc

=== Track Layout Block (`TKLY`)

The `TKLY` block defines the mapping between physical tracks and logical sectors, as referenced by the deduplication table.

Magnetic media such as floppies and hard disks may exhibit complex physical layouts that do not cleanly translate to logical block addresses.
This block enables accurate sector location resolution by maintaining explicit layout information.

Each `TKLY` block corresponds to a unique combination of (sub)track and head, and is followed by a series of sector mapping entries.
If known, sectors should be listed in physical order to preserve potential interleaving.
Sector numbers may be duplicated.

NOTE: This block must not be used for optical or other logically addressable block-based media.

If a referenced LBA is marked as undumped and a `FLUX` block is present, it indicates the corresponding sector could not be decoded (e.g., damaged or unreadable), and should be considered undumped unless flags state otherwise.

If a `FLUX` block exists for a given (sub)track but no corresponding `TKLY` block is present, the entire (sub)track is considered not decoded.

==== Structure Definition

[source,c]
/* Undefined */

==== Field Descriptions

[cols="2,2,2,6",options="header"]
|===
|Type
|Size
|Name
|Description

|uint32_t
|4 bytes
|identifier
|The track layout block identifier, always `TKLY`

|uint64_t
|8 bytes
|crc64
|The CRC64-ECMA checksum of the data following this header

|uint32_t
|4 bytes
|head
|Head the block corresponds to

|uint16_t
|2 bytes
|track
|Track the block corresponds to

|uint8_t
|1 byte
|subtrack
|Substep of a track the data corresponds to

|uint16_t
|2 bytes
|sectors
|Number of sectors in this (sub)track, and therefore, number of entries following this header

|uint64_t
|8 bytes
|flux
|Pointer to the flux data block that contains the flux information for this (sub)track

|uint64_t
|8 bytes
|bitstream
|Pointer to the bitstream data block that contains the flux information for this (sub)track
|===

==== Sector Mapping Entries

[source,c]
/* Undefined */

==== Field Descriptions

[cols="2,2,2,6",options="header"]
|===
|Type
|Size
|Name
|Description

|uint16_t
|2 bytes
|sector
|Sector number as present in the appropriate media sector header or equivalent

|uint64_t
|8 bytes
|block
|Position in the deduplication table this sector and its flags is stored
|===