Data Sheet

Ethernet Controller I210 —Inline Functions
292
7.2.2.2.3 LaunchTime (25)
The LaunchTime field is only used in Qav mode when a queue is configured as SR queue. The
LaunchTime value is used to
1. calculate the fetch time - this time defines the time to fetch the packet from the host to the packet
buffer, and
2. define the launch time - the time to transmit a packet from the packet buffer.
The LaunchTime is a 25 bit field defined in 32 nsec units (Launch time = LaunchTime * 32). The Launch
time is compared against the SYSTIML register ignoring the SYSTIMH value. It means that the Launch
time is defined relative to the fraction of a second of the SYSTIM.
• The Launch time is defined as expired if it is smaller or equal to the SYSTIML.
• The Launch time is defined as greater than SYSTIML if it is in the range of [SYSTIML … SYSTIML +
0.5 sec).
• It is defined as smaller than SYSTIML if it is in the range of [SYSTIML - 0.5 sec … SYSTIML).
Notes: The operations SYSTIML + 0.5 sec and SYSTIML - 0.5 sec are modulo 1 sec.
For meaningful operation, the Launch time should never be set to larger value than SYSTIML
+ 0.5sec. Otherwise, the Launch time might be misinterpreted.
The LaunchTime parameter is a relative time to the LaunchOffset parameter in the
LAUNCH_OS0 register. So, the actual Launch time equals to 32 * (LaunchOffset +
LaunchTime).
7.2.2.2.4 TUCMD (11)
• RSV (bit 10:4) - Reserved
• L4T (bit 3:2) - L4 Packet TYPE (00b: UDP; 01b: TCP; 10b: SCTP; 11b: Reserved)
• IPV4 (bit 1) - IP Packet Type: When 1b, IPv4; when 0b, IPv6
• SNAP (bit 0) - SNAP indication
7.2.2.2.5 DTYP(4)
Always 0010b for this type of descriptor.
7.2.2.2.6 DEXT(1)
Descriptor Extension (1b for advanced mode).
Table 7-31. Transmit Command (TDESC.TUCMD) Layout
10 4 3 2 1 0
Reserved L4T IPV4 SNAP