FW82801EB Intel, FW82801EB Datasheet - Page 197

• Manufacturer Part Number: FW82801EB
• Manufacturer: Intel

Specifications of FW82801EB

• Lead Free Status / RoHS Status: Not Compliant

5.19.1.3
Intel
®
Table 86. Queue Head Block
Table 87. Queue Head Link Pointer
Table 88. Queue Element Link Pointer
82801EB ICH5 / 82801ER ICH5R Datasheet
Queue Head (QH)
Queue heads are special structures used to support the requirements of Control, Bulk, and Interrupt
transfers. Since these TDs are not automatically retired after each use, their maintenance
requirements can be reduced by putting them into a queue. Queue Heads must be aligned on a
16-byte boundary, and the elements are shown in
1
00–03
04–07
Bytes
31:4
31:4
Bit
3:2
Bit
3:2
0
1
0
Queue Head Link Pointer (QHLP). This field contains the address of the next data object to be
processed in the horizontal list and corresponds to memory address signals [31:4], respectively.
Reserved. These bits must be written as 0s.
QH/TD Select (Q). This bit indicates to the hardware whether the item referenced by the link
pointer is another TD or a QH.
0 = TD
1 = QH
Terminate (T). This bit indicates to the Intel
are active TDs in this queue, they are the last to be executed in this frame.
0 = Pointer is valid (points to a QH or TD).
1 = Last QH (pointer is invalid).
Queue Element Link Pointer (QELP). This field contains the address of the next TD or QH to be
processed in this queue and corresponds to memory address signals [31:4], respectively.
Reserved.
QH/TD Select (Q). This bit indicates to the hardware whether the item referenced by the link
pointer is another TD or a QH. For entries in a queue, this bit is typically set to 0.
0 = TD
1 = QH
Terminate (T). This bit indicates to the Intel
When HCD has new queue entries it overwrites this value with a new TD pointer to the queue
entry.
0 = Pointer is valid.
1 = Terminate (No valid queue entries).
Queue Head Link Pointer
Queue Element Link Pointer
Description
Description
Description
Table
®
®
ICH5 that this is the last QH in the schedule. If there
ICH5 that there are no valid TDs in this queue.
86.
Functional Description
Attributes
R/W
RO
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