Configuration

A blob is a contiguous, self-describing binary region. All multi-byte fields are stored in big-endian byte order. The region begins with a fixed-size header, followed by the blob data, which is itself a sequence of configurations.

Blob layout

Field	Size	Description
`version`	4 bytes	Blob format version. Currently `0x00000001`.
`magic`	4 bytes	Magic number identifying a blob. Always `0xDEADBEEF`.
`size`	4 bytes	Size, in bytes, of the blob data that follows the header.
`data`	`size`	Concatenated configurations (see below).

The header is consumed by checkHeader() (see blob APIs), which verifies the version and magic number and records the declared data size. The Blob constructor additionally checks that the actual memory region matches HEADER_SIZE + size.

Configuration layout

Each configuration inside the blob data has its own header followed by a payload. The type field identifies how the payload should be interpreted.

Field	Size	Description
`type`	4 bytes	Configuration type identifier (see Configuration types below).
`reserved`	8 bytes	Reserved space, i.e., configuration-specific data that is not interpreted by the blob module.
`size`	4 bytes	Size, in bytes, of the configuration `data` (including padding and the trailing CRC).
`data`	`size`	Configuration payload, optionally padded, ending with a 4-byte CRC.

The last four bytes of every configuration data hold a big-endian CRC computed over the full configuration entry bytes except these final CRC bytes. In other words, the CRC input starts at type and includes reserved, size, and the payload bytes. The CRC is verified by checkCrc(), which re-computes a 32-bit CRC using etl::crc32 (standard CRC-32). The payload is padded with 0xFF bytes so that its length is a multiple of four before the CRC is appended.

Configuration types

The supported configuration types are defined by the ConfigType enum:

Type	Value	Description
`ROUTING`	`0x00`	PDU routing table.
`RX_ADAPTER`	`0x01`	RX adapter table.
`TX_ADAPTER`	`0x02`	TX adapter table.
`CHANNEL`	`0xCC`	Channel configuration.
`CHANNEL_NAMES`	`0xDD`	Channel name configuration.
`META`	`0xFE`	Metaconfiguration: a list of descriptive strings about other configurations.
`UNKNOWN`	`0xFFFFFFFF`	Sentinel for an unrecognized configuration type.

A byte-level example of a complete blob containing a CHANNEL_NAMES and a ROUTING configuration is given in Examples.