#
# This message is used for dynamic Node ID allocation. This algorithm is an optional extension to the UAVCAN
# specification, and it is not mandatory to support it.
#
# On the client's side the protocol is defined through the following set of rules:
#
# Rule A. On initialization:
# 1. The client subscribes to this message.
# 2. The client starts the Request Timer with interval of DEFAULT_REQUEST_INTERVAL_MS.
#
# Rule B. On expiration of Request Timer:
# 1. Request Timer restarts.
# 2. The client broadcasts a first-stage Allocation request message, where the fields are assigned following values:
#    node_id                 - preferred node ID, or zero if the client doesn't have any preference
#    first_part_of_unique_id - true
#    unique_id               - first MAX_LENGTH_OF_UNIQUE_ID_IN_REQUEST bytes of unique ID
#
# Rule C. On any Allocation message, even if other rules also match:
# 1. Request Timer restarts.
#
# Rule D. On an Allocation message WHERE (source node ID is non-anonymous) AND (client's unique ID starts with the
# bytes available in the field unique_id) AND (unique_id is less than 16 bytes long):
# 1. The client broadcasts a second-stage Allocation request message, where the fields are assigned following values:
#    node_id                 - same value as in the first-stage
#    first_part_of_unique_id - false
#    unique_id               - at most MAX_LENGTH_OF_UNIQUE_ID_IN_REQUEST bytes of local unique ID with an offset
#                              equal to number of bytes in the received unique ID
#
# Rule E. On an Allocation message WHERE (source node ID is non-anonymous) AND (unique_id fully matches client's
# unique ID) AND (node_id in the received message is not zero):
# 1. Request Timer stops.
# 2. The client initializes its node_id with the received value.
# 3. The client terminates subscription to Allocation messages.
# 4. Exit.
#

#
# Recommended request transmission period.
#
uint16 DEFAULT_REQUEST_PERIOD_MS = 1000

#
# Any request message can accommodate no more than this number of bytes of unique ID.
# This limitation is needed to ensure that all request transfers are single-frame.
#
uint8 MAX_LENGTH_OF_UNIQUE_ID_IN_REQUEST = 7

#
# If transfer is anonymous, this is the preferred ID.
# If transfer is non-anonymous, this is allocated ID.
#
uint7 node_id

#
# If transfer is anonymous, this field indicates first-stage request.
# If transfer is non-anonymous, this field should be ignored.
#
bool first_part_of_unique_id

#
# If transfer is anonymous, this array must not contain more than MAX_LENGTH_OF_UNIQUE_ID_IN_REQUEST items.
# Note that array is tail-optimized, i.e. it will not be prepended with length field.
#
uint8[<=16] unique_id