FLP Format
FLP uses a TLV encoding scheme to store its data. Unlike JSON and XML where data is already stored like an object, converting this bulk of data into a proper object model gets quite tricky.
Structure of an FLP event
| Field | Size | Notes |
|---|---|---|
| event_id | 1 | For classification of the type of event. |
| length | varint | Used only by TextEvent and DataEvent |
| data | 1, 2, 4 or length |
Size decided by event_id (see below) |
where size of data is decided by
event_id |
Size | Notes |
|---|---|---|
| 0-63 | 1 | ByteEvent |
| 63-127 | 2 | WordEvent |
| 128-191 | 4 | DWordEvent |
| 192-207 | length |
TextEvent |
| 208-255 | length |
DataEvent |
Variable-sized events (TextEvent and DataEvent) are used for storing
strings or a blob of a collection of various simple types like int, bool,
float etc. Since event_id can hold only 256 different values, it is easier
to use just a single event_id > 192 and store all sorts of data in it without
worrying a lot about size and event ID space.
DataEvents
As newer features get introduced, many times IL just adds more data at the
end of an existing DataEvent, making for e.g. a 62 byte event in FL 20
to a 66 byte event in a later version.