RTL8181 Wireless LAN Access Point/Gateway Controller DATA ...

RTL81810 15-0 Frame_Le Transmit frame length. This field indicates the length in TX buffer, inngth byte, to be transmitted4 31-18 RSEV Reserved.4 17-16 TAGC VLAN tag control bits:00: Packet remains unchanged when transmitting10: Add TAG. 0x8100 (Ethernet encoded tag protocol ID, indicatingthat this is a IEEE 802.1Q VLAN packet) is inserted after sourceaddress, and 2 bytes are inserted after tag protocol ID fromVLAN_TAG field in transmit descriptor.4 15-0 VLAN_TAGThe 2-byte VLAN_TAG contains information, from upper layer, ofuser priority, canonical format indicator, and VLAN ID. Please refer toIEEE 802.1Q for detailed VLAN tag information.8 31-0 TxBuff Logic Address of transmission buffer.Tx Status Descriptor (after transmitting, OWN=0, Tx status mode) After having transmitted, the Tx descriptor turns to be a Txstatus descriptor.31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0CC3-0Offset 0OWN=0EORFSLSRESVRESVUNFRESVTESRESVOWCLNKFEXCTAGCFrame_LengthVLAN_TAGOffset 4TX_BUFFER_ADDRESSDummyOffset 8Offset 12Byte Bit# Bit Name DescriptionOffset#0 31 OWN When set, indicates that the descriptor is owned by NIC. When clearindicates that the descriptor is owned by host system. NIC clears thisbit when the relative buffer data is already transmitted. In this case,OWN=0.0 30 EOR End of descriptor Ring. When set, indicates that this is the lastdescriptor in descriptor ring. When NIC’s internal transmit pointerreaches here, the pointer will return to the first descriptor of thedescriptor ring after transmitting the data relative to this descriptor.0 29 FS First segment descriptor. When set, indicates that this is the firstdescriptor of a Tx packet, and this descriptor is pointing to the firstsegment of the packet.0 28 LS Last segment descriptor. When set, indicates that this is the lastdescriptor of a Tx packet, and this descriptor is pointing to the lastsegment of the packet.0 27-26 - Reserved.0 25 UNF FIFO underrun. A status bit. NIC sets this bit to inform driver thatFIFO underrun had ever occurred before this packet transmitted.0 24 - Reserved.0 23 TES Transmit Error Summary. When set, indicates that at least one of thefollowing errors occurred: OWC, EXC, LNKF. This bit is valid onlywhen LS (Last segment bit) is set.27CONFIDENTIAL v1.0