Function rumq_core::qos

pub fn qos(num: u8) -> Result<QoS, Error>

7 3 0 +--------------------------+--------------------------+ byte 1 | MQTT Control Packet Type | Flags for each type | +--------------------------+--------------------------+ | Remaining Bytes Len (1 - 4 bytes) | +-----------------------------------------------------+

http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#Figure_2.2-