82801DB Datasheet, PDF (183/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

Functional Description
QH
QHLP
QT
QE ^{QELP Vf Q T}
TD
TDLP Vf Q T
Legends:
QH.LP = Queue Head Link Pointer (or Horizontal Link Pointer)
QE.LP = Queue Element Link Pointer (or Vertical Link Pointer)
TD.LP = TD Link Pointer
QH.Q = Q bit in QH
QH.T = T bit in QH
QE.Q = Q bit in QE
QE.T = T bit in QE
TD. Vf = Vf bit in TD
TD.Q = Q bit in TD
TD. T = T bit in TD
Table 5-66. USB Schedule List Traversal Decision Table
Q
Context
QH.Q
QH.T
QE.Q
QE.T
TD.Vf
TD.Q
0
—
—
—
—
x
0
0
—
—
—
—
x
x
0
—
—
—
—
x
1
1
0
0
0
0
0
x
1
x
x
0
0
1
0
1
x
x
0
0
1
1
1
0
0
x
1
x
x
1
x
x
1
0
—
—
1
x
1
0
0
0
x
1
x
1
x
1
x
x
1
1
0
0
0
0
x
1
1
0
x
1
x
x
TD.T
0
1
0
x
0
0
x
—
x
x
x
x
Description
• Not in Queue - execute TD.
• Use TD.LP to get next TD
• Not in Queue - execute TD. End of Frame
• Not in Queue - execute TD.
• Use TD.LP to get next (QH+QE).
• Set Q Context to 1.
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• Use QH.LP to get next TD.
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• Use TD.LP to get next TD.
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• Use TD.LP to get next (QH+QE).
• In Queue. Empty queue.
• Use QH.LP to get next TD
• In Queue. Use QE.LP to get (QH+QE)
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• End of Frame
• In Queue. Empty queue. End of Frame
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• Use QH.LP to get next (QH+QE).
• In Queue. Empty queue.
• Use QH.LP to get next (QH+QE)
Intel^® 82801DB ICH4 Datasheet
183