Function messageCrcExtra

messageCrcExtra(name: string, fields: mavlink.MavlinkField[]): number
Derives the CRC_EXTRA seed of a message from its definition.

This is what makes a dialect this build has never seen usable: given a message's name and its base fields in wire order, the seed comes out the same as the one the dialect publishes, and a frame carrying that message then checks like any other.

Extension fields are excluded from the seed and must not be listed, which is what lets a peer that predates them still check the frame.
Parameters
- name: string
  The message name, such as HEARTBEAT.
- fields: mavlink.MavlinkField[]
  The base fields in wire order.
Returns number
The seed.
Example
```
const seed = messageCrcExtra('PRIVATE_STATUS', [
  { typeName: 'uint32_t', fieldName: 'uptime' },
])
```
- Defined in mavlink/dist/index.d.ts:90