FW82801EB Intel, FW82801EB Datasheet - Page 201

• Manufacturer Part Number: FW82801EB
• Manufacturer: Intel

Specifications of FW82801EB

• Lead Free Status / RoHS Status: Not Compliant

Intel
®
Figure 21. Example Queue Conditions
82801EB ICH5 / 82801ER ICH5R Datasheet
represents the last data structure in the current Frame. The T bit informs the ICH5 that no further
processing is required until the beginning of the next frame. The second DWord is a vertical pointer
(Queue Element Link Pointer) to the first data structure (TD or QH) being managed by this QH. If
the T bit is set, the queue is empty. This pointer may reference a TD or another QH.
Figure 21
“empty” queue; the termination bit (T Bit), in the vertical link pointer field, is set to 1. The
horizontal link pointer references another QH. The next queue is the expected typical
configuration. The horizontal link pointer references another QH, and the vertical link pointer
references a valid TD.
Typically, the vertical pointer in a QH points to a TD. However, as shown in
example from left side of figure) the vertical pointer could point to another QH. When this occurs,
a new Q Context is entered and the Q Context just exited is NULL (ICH5 will not update the
vertical pointer field).
The far right QH is an example of a frame “termination” node. Since its horizontal link pointer has
its termination bit set, the ICH5 assumes there is no more work to complete for the current frame.
Transfer Queues are based on the following characteristics:
In the simplest model, the ICH5 follows vertical link point to a queue element, then executes the
element. If the completion status of the TD satisfies the advance criteria as shown in
ICH5 advances the queue by writing the just-executed TD’s link pointer back into the QH’s Queue
Element link pointer. The next time the queue head is traversed, the next queue element will be the
Top element.
•
•
Indicates 'NULL' Queue Head
A QH’s vertical link pointer (Queue Element Link Pointer) references the “Top” queue
member. A QH’s horizontal link pointer (Queue Head Link Pointer) references the “next”
work element in the Frame.
Each queue member’s link pointer references the next element within the queue.
Link Pointer (Horz
field in QH DWord 0
Link Pointer (Vert)=Queue Element Link Pointer
field in QH DWord 1
31
31
Frame List Pointer
Link Pointer (Horiz) Q T
Link Pointer (Vert)
illustrates four example queue conditions. The first QH (on far left) is an example of an
QH
z
)=Queue Head Link Pointer
2
2
1
1
Q T
Q T
0
0
31
Link Pointer (Horiz) Q T
Link Pointer (Vert)
Link Pointer
Link Pointer
QH
TD
TD
2
1
Q T
Q T
Q T
0
31
31
Link Pointer (Vert)
Link Pointer (Horiz) Q T
Link Pointer (Horiz) Q T
Link Pointer (Vert)
Link Pointer
Link Pointer
QH
QH
TD
TD
2
2
Q T
1
1
Q T
Q T
Q T
0
0
Functional Description
Indicates 'Nil' Next Pointer
Figure 21
31
Indicates 'Nil' Next Pointer
Link Pointer (Horiz) Q T
Link Pointer (Vert)
Link Pointer
QH
Table
TD
(third
90, the
2
1
Q T
Q T
0
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