Address Member
The following example shows the eight bits that are contained in the address member of an IrLAP frame.
C/R |
A |
A |
A |
A |
A |
A |
A |
The first bit of the address member is used as the command and response (C/R) bit. If this bit is set, the packet specifies that it is being sent from the primary station to the secondary station. If the C/R bit is clear, the packet specifies that it is being sent from the secondary station to the primary station. Because the IrDA miniport driver does not require information about the C/R bit, the driver does not monitor the bit. Note that primary stations initiate connections to secondary stations and run the timers that keep those connections active.
The least-significant 7 bits of the address member specify the Link Access Protocol (LAP) address. The LAP address is the address of a device that belongs to a particular IrDA miniport driver. The IrDA miniport driver transmits and receives packets through this device.
The IrLAP protocol can specify a list of addresses of devices from which it can receive packets; thereby restricting all other devices from receiving packets. To specify this list, the IrLAP protocol requests the IrDA miniport driver to set addresses in a UNICAST list using OID_IRDA_UNICAST_LIST. A UNICAST list is an array of addresses of devices from which the IrDA miniport driver accepts packets. If the UNICAST list is set, the IrDA miniport driver must accept only valid infrared packets from the specified addresses. If the UNICAST list is not set or contains zero elements, the IrDA miniport driver must accept all valid infrared packets. The IrDA miniport driver then indicates packets up to the IrLAP protocol.