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Receive and Transmit Description
42 Software Developer’s Manual
3.3.6 TCP/IP Context Descriptor Layout
The following section describes the layout of the TCP/IP context transmit descriptor.
To select this descriptor format, bit 29 (TDESC.DEXT) must be set to 1b and TDESC.DTYP must
be set to 0000b. In this case, the descriptor format is defined as shown in Table 3-13.
Note that the TCP/IP context descriptor does not transfer any packet data. It merely prepares the
checksum hardware for the TCP/IP Data descriptors that follow.
Table 3-13. Transmit Descriptor (TDESC) Layout – (Type = 0000b)
Note: The first quadword of this descriptor type contains parameters used to calculate the two checksums
which may be offloaded.
63 48 47 40 39 32 31 16 15 8 7 0
0 TUCSE TUCSO TUCSS IPCSE IPCSO IPCSS
8 MSS HDRLEN RSV STA TUCMD DTYP PAYLEN
63 48 47 40 39 36 35 32 31 24 23 20 19 0