INTEL82801 Datasheet, PDF (135/414 Pages) Intel Corporation – 82801AB (ICH0) I/O Controller Hub

Functional Description
Table 5-63 is a decision table illustrating the valid combinations of link pointer bits and the valid
actions taken when advancement criteria for a queued transfer descriptor are met. The column
headings for the link pointer fields are encoded, based on the following list:
QH
QHLP Q _T
TD
TDLP Vf Q T
QE ^{QELP 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 5-64. USB Schedule List Traversal Decision Table
Q
Context
QH.Q
0
-
0
-
0
-
1
0
1
x
1
x
1
0
1
x
1
x
1
x
1
1
1
1
QH.T
-
-
-
0
x
x
0
x
1
1
0
0
QE.Q
-
-
-
0
0
0
x
1
0
x
0
x
QE.T
-
-
-
0
0
0
1
0
0
1
0
1
TD.Vf TD.Q
x
0
x
x
x
1
0
x
1
0
1
1
x
x
-
-
0
x
x
x
0
x
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)
82801AA and 82801AB Datasheet
5-85