dp83820 National Semiconductor Corporation, dp83820 Datasheet - Page 23

• Manufacturer Part Number: dp83820
• Description: 10/100/1000 Mb/s Pci Ethernet Network Interface Controller
• Manufacturer: National Semiconductor Corporation

3.0 Functional Description
3.13.2.4 Descriptor Lists
Descriptors may also be organized in linked lists using the
link field. The linked list may be terminated by either a
NULL link field, or by using the descriptor OWN bit. A list of
descriptors may represent any number of packets or packet
addr 10100
addr 10100
addr 10100
own
10140
10140
10140
Descriptors Organized in a Ring (Recommended Method)
Figure 3-13 Linked List Descriptor Organization
Figure 3-12 Ring Descriptor Organization
(Continued)
addr 10140
Linked List terminated by NULL link field
Linked List terminated by OWN bit
addr 10140
addr 10140
own
10180
10180
10180
23
fragments. Care should be used when implementing a
linked list terminated by a NULL link as there is a potential
for driver software and the device to get out of sync. Before
clearing a link field when freeing up descriptors, the driver
should verify that the device has already traversed the link.
addr 10180
addr 10180
addr 10180
own
101C0
101C0
101C0
addr 101C0
addr 101C0
addr 101C0
!own
10100
00000
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