Rainbow Electronics DS3134 - Manual (Page 126)

DS3134
126 of 203
Transmit DMA Priority Packet Handling Figure 8.2.1D
Buffer 1
Packet 1
1st Descriptor
(EOF=0/CV=0)
Buffer 2
Packet 1
2nd Descriptor
(EOF=0/CV=0)
Buffer 3
Packet 1
Last Descriptor
(EOF=1/CV=1)
Buffer 1
Packet 2
Last Descriptor
(EOF=1/CV=0)
Buffer 1
Pri. Packet 1
1st Descriptor
(EOF=0/CV=0)
Buffer 2
Pri. Packet 1
Last Descriptor
(EOF=1/CV=1)
Buffer 1
Pri. Packet 2
Last Descriptor
(EOF=1/CV=0)
Buffer 1
Pri. Packet 3
Last Descriptor
(EOF=1/CV=0)
Buffer 1
Pri. Packet 4
1st Descriptor
(EOF=0/CV=0)
Buffer 2
Pri. Packet 4
2nd Descriptor
(EOF=0/CV=0)
Buffer 3
Pri. Packet 4
Last Descriptor
(EOF=1/CV=0)
Next Descriptor Pointer
Start Descriptor Pointer
Transmit DMA Configuration RAM
dmatppf
Normal
Path if No
Priority
Packets
Had
Occurred
Service
Priority
Packets
All Priority Packets Have Been Serviced
Next Pending Descriptor Pointer
Last Pending Descriptor Pointer
Next Pending Descriptor Pointer
Next Descriptor Pointer
Last Pending Descriptor Pointer
Standard Queue Pointers
Priority Queue Pointers
Note #1
The Start Descriptor Pointer field in the Transmit DMA Configuration RAM is used by
both the nomal and priority pending queues.
See
Note #1
Below
PV = 1
Next Pending
Descriptor Pointer
stored within the
Packet Descriptor
Standard
Packet Chain
Column 1 Priority
Packet Chain
Column 2 Priority
Packet Chain
Column 3 Priority
Packet Chain
Column 4