Cirrus-logic EP93xx Instrukcja Użytkownika Strona 327

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DS785UM1 9-25
Copyright 2007 Cirrus Logic
1/10/100 Mbps Ethernet LAN Controller
EP93xx User’s Guide
9
9
9.2.3.6 Receive Frame Pre-Processing
The MAC pre-processes all incoming receive frames. First the frame is either passed on to
the next level or discarded according to the destination address filter. The next decision is
whether to accept the frame. A frame is accepted when the frame data are brought into MAC
through internal memory. The final step in frame pre-processing is the decision on causing an
interrupt. These pre-processing steps are detailed in Figure 9-12.
Figure 9-12. Receive Frame Pre-processing
In c o m in g F ra m e
Destination
Address
Filter
PromiscuousA
IA H a s h A
MulticastA
IndividualA
BroadcastA
Filter Taps:
If the filter is not passed,
the fram e is discarded.
Filter Passed
Accept (A)
Mask
CRCRuntA
RuntA
A
ccept Masks:
Accept M ask
NOT
PASSED
Accept Mask
PASSED
Status in RxEvent
and the Fram e Body
is Accepted into the chip
iE
Mask
iE -M as k Taps :
In terru pt if M ask O
K
fram e
discarded
Fram e is passed
to host m em ory
by descriptor
processor
ReceiveStQiE
EndOfSream iE
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