aaru-dps/libaaruformat
1
0
Fork 0
mirror of https://github.com/aaru-dps/libaaruformat.git synced 2026-02-04 05:24:56 +00:00
Code Issues 3 Packages Projects Releases Wiki Activity

Use block alignment offset instead of absolute offset

Browse Source
This commit is contained in:
Rebecca Wallander
2026-01-01 12:51:26 +01:00
parent 86b6680e3e
commit c412030a8b
5 changed files with 53 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
docs/spec/blocks/flux.adoc
View File

@@ -19,7 +19,7 @@ The flux capture system uses two block types:
* `DataStreamPayloadBlock` (`DSPL` / `0x4C505344`): Contains the actual flux data payload (data and index buffers) for individual captures. This is a generic block type that can also be used for other data streams.
Each flux capture has one entry in the `FluxDataBlock` and one corresponding `DataStreamPayloadBlock` containing its data.
The `FluxEntry` structure in the data block contains a `payloadOffset` field that points to the file offset where the corresponding `DataStreamPayloadBlock` is stored.
The `FluxEntry` structure in the data block contains a `payloadOffset` field that points to the file offset where the corresponding `DataStreamPayloadBlock` is stored. The offset is stored divided by the block alignment (as indicated by `blockAlignmentShift` in the `FluxHeader`), consistent with DDT table offset storage.
==== Structure Definition
@@ -28,9 +28,10 @@ The `FluxEntry` structure in the data block contains a `payloadOffset` field tha
/** Flux data block header */
typedef struct FluxHeader
{
uint32_t identifier; ///< Block identifier, must be BlockType::FluxDataBlock (0x58554C46).
uint16_t entries; ///< Number of FluxEntry records following this header.
uint64_t crc64; ///< CRC64-ECMA checksum of the FluxEntry array (header excluded).
uint32_t identifier; ///< Block identifier, must be BlockType::FluxDataBlock (0x58554C46).
uint16_t entries; ///< Number of FluxEntry records following this header.
uint8_t blockAlignmentShift; ///< Block alignment shift: 2^blockAlignmentShift = block alignment boundary in bytes.
uint64_t crc64; ///< CRC64-ECMA checksum of the FluxEntry array (header excluded).
} FluxHeader;
==== Field Descriptions
@@ -52,6 +53,11 @@ typedef struct FluxHeader
|entries
|The number of flux entry records following this header
|uint8_t
|1 byte
|blockAlignmentShift
|Block alignment shift: 2^blockAlignmentShift = block alignment boundary in bytes. Used to decode payloadOffset values in FluxEntry structures, which are stored divided by this alignment. Stored in the header to make the block self-contained, similar to DDT headers.
|uint64_t
|8 bytes
|crc64
@@ -121,5 +127,5 @@ typedef struct FluxEntry
|uint64_t
|8 bytes
|payloadOffset
|File offset where the DataStreamPayloadBlock containing this capture's data is stored.
|Block-aligned file offset where the DataStreamPayloadBlock containing this capture's data is stored, divided by (1 << blockAlignmentShift). To get the absolute file offset, multiply by (1 << blockAlignmentShift) using the blockAlignmentShift value from FluxHeader. This storage method is consistent with DDT table offset storage.
|===