Cirrus Logic EP93xx - Manual (Page 329)

DS785UM1 9-27
Copyright 2007 Cirrus Logic
1/10/100 Mbps Ethernet LAN Controller
EP93xx User’s Guide
9
9
9
Figure 9-13. Transmit Descriptor Format and Data Fragments
TxDesQB (32)
register sizes are in bits,
and shown in parentheses ().
TxBufAdr 0 (32)
Buffer
Index 0 (15)
Buffer
Length 0 (12)
Data Fragment 0 Fragment 0
Length
in bytes
Transmit Descriptor Format
and Data Fragments
Data Fragment 1
Fragment 1
Length
in bytes
number of bytes set in
TxDesQLen
Data Fragment 2
Fragment 2
Length
in bytes
Data Fragment n
Fragment n
Length
in bytes
Each Data Fragment
may begin on any byte
boundary, and may
end on any byte
boundary.
E O F
( 1 ) Buffer
Cmd 0 (4)
TxBufAdr 1 (32)
Buffer
Index 1 (15)
Buffer
Length 1 (12)
E O F
( 1 ) Buffer
Cmd 1 (4)
TxBufAdr 2 (32)
Buffer
Index 2 (15)
Buffer
Length 2 (12)
E O F
( 1 ) Buffer
Cmd 2 (4)
TxBufAdr n (32)
Buffer
Index n (15)
Buffer
Length n (12)
E O F
( 1 ) Buffer
Cmd n (4)