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5.0 Buffer Management
(Continued)
DP83816
Table 5-4 Receive Status Bit Definitions
5.1.2 Single Descriptor Packets
To represent a packet in a single descriptor, the MORE bit in the cmdsts field is set to 0.
Figure 5-1 Single Descriptor Packets
Bit
Tag
Description
Usage
26
RXA
Receive Aborted
Set to 1 by DP83816 when the receive was aborted, the value of
this bit always equals RXO. Exists for backward compatibility.
25
RXO
Receive Overrun
Set to 1 by DP83816 to indicate that a receive overrun condition
occurred. RXA will also be set.
24-23
DEST
Destination Class
When the receive filter is enabled, these bits will indicate the
destination address class as follows:
00 - Packet was rejected
01 - Destination is a Unicast address
10 - Destination is a Multicast address
11 - Destination is a Broadcast address
If the Receive Filter is enabled, 00 indicates that the packet was
rejected. Normally packets that are rejected do not cause any bus
activity, nor do they consume receive descriptors. However, this
condition could occur if the packet is rejected by the Receive Filter
later in the packet than the receive drain threshold
(RXCFG:DRTH).
Note:
The DEST bits may not represent a correct DA class for runt
packets received with less than 6 bytes.
22
LONG
Too Long Packet
Received
If RXCFG:ALP=0, this flag indicates that the size of the receive
packet exceeded 1518 bytes.
If RXCFG:ALP=1, this flag indicates that the size of the receive
packet exceeded 2046 bytes.
21
RUNT
Runt Packet Received The size of the receive packet was less than 64 bytes (inc. CRC).
20
ISE
Invalid Symbol Error
(100 Mb/s only) An invalid symbol was encountered during the
reception of this packet.
19
CRCE
CRC Error
The CRC appended to the end of this packet was invalid.
18
FAE
Frame Alignment Error The packet did not contain an integral number of octets.
17
LBP
Loopback Packet
The packet is the result of a loopback transmission.
16
COL
Collision Activity
The receive packet had a collision during reception.
link
ptr
MAC hdr
netwk hdr
data
0
64
single descriptor / single fragment
Содержание DP83816AVNG
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