Structure Of The Transmit Queue; Packet Info Structure - NEC uPD98502 User Manual

4.8.2.2 Transmit queue
Tx_Ready command has to be issued in order to transmit a packet. However, V
indication before issuing next Tx_Ready command for the same VC. When V
before completing transmission process for the previous packet, ATM Cell Processor builds Tx Queue for that VC.
P ack etInfo

(1) Packet info structure

The Maximum number of Packet Info Structure for each VC is 16. However, since total number of Packet Info
Structure is 128, some VC may not obtain 16 Packet Info Structure depend on the queue length of other VCs. When
ATM Cell Processor can not obtain any Packet Info Structure, ATM Cell Processor returns an error indication for
Tx_Ready command.
CELL HEADER
PACKET DESCRIPTOR STORAGE
NEXT POINTER
CHAPTER 4 ATM CELL PROCESSOR
Figure 4-25. Structure of the Transmit Queue
T x V C T able
First Last
P ack etInfo
Figure 4-26. Packet Info Structure
W O R D 0
W O R D 1
P A C K E T D E S C R I P T O R S T O R A G E
W O R D 2
W O R D 3
Cell header
Area for temporarily storing the packet descriptor of a packet
Address of the next Packet Info structure
Preliminary User's Manual S15543EJ1V0UM
4120A issues Tx_Ready command
R
P ack etInfo
S tructure
P ack etInfo
S tructure
P ack etInfo
S tructure
C E L L H E A D E R
NEXT POINTER
4120A doesn't have to wait Tx
R
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