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Intel
®
81341 and 81342—Inter-Processor Messaging Unit
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
832
Order Number: 315037-002US
13.6.1
Door Bell Control Register — DBCR
The Door Bell Control Register (DBCR) contains the Door Bell and Circular Queue
interrupt status bits that are used to manage the two messaging schemes. The DBCR
includes the output of a fixed prioritization of the Doorbell and Circular Queue interrupt
status bits, respectively. In addition, Door Bell interrupt status bits may be cleared via
the DBCR.
Table 508. Door Bell Control Register — DBCR (Sheet 1 of 2)
Bit
Default
Description
31:28
1111
2
Highest Priority Door Bell -- Performs a fixed priority decode of the 15-bit Door Bell Status field
(DBSTAT) of the DBCR. Highest priority is the lowest order Door Bell Status Bit Set.
0 DBSTAT0 8 DBSTAT8
1 DBSTAT1 9 DBSTAT9
2 DBSTAT2 10 DBSTAT10
3 DBSTAT3 11 DBSTAT11
4 DBSTAT4 12 DBSTAT12
5 DBSTAT5 13 DBSTAT13
6 DBSTAT6 14 DBSTAT14
7 DBSTAT7 15 None (Default Value)
27:24
1111
2
Highest Priority Circular Queue Attention -- Performs a fixed priority decode of the 8 Circular Queue
Attention Bits (bits 23 to 16 of the DBCR). Highest priority is the lowest order Bit Set.
0 S0NF 8 Reserved
1 R0NE 9 Reserved
2 S1NF 10 Reserved
3 R1NE 11 Reserved
4 S2NF 12 Reserved
5 R2NE 13 Reserved
6 S3NF 14 Reserved
7
R3NE
15
None (Default Value)
23
0
2
Receive Queue 3 Not Empty (R3NE) -- When set, Receive Queue 3 is not empty
(Receive Queue 3 Get Pointer Does
not
equal
Receive Queue 3 Put Pointer)
22
0
2
Send Queue 3 Not Full (S3NF) -- When set, Send Queue 3 is not Full and ES3NF is set in the Door Bell
Enable Register.
(Send Queue 3 Put Pointer
minus
Send Queue 3 Get Pointer
does
not
equal Send Queue 3 Size)
21
0
2
Receive Queue 2 Not Empty (R2NE) -- When set, Receive Queue 2 is not empty
(Receive Queue 2 Get Pointer Does
not
equal
Receive Queue 2 Put Pointer)
20
0
2
Send Queue 2 Not Full (S2NF) -- When set, Send Queue 2 is not Full and ES2NF is set in the Door Bell
Enable Register.
(Send Queue 2 Put Pointer
minus
Send Queue 2 Get Pointer
does
not
equal Send Queue 2 Size)
19
0
2
Receive Queue 1 Not Empty (R1NE) -- When set, Receive Queue 1 is not empty
(Receive Queue 1 Get Pointer Does
not
equal
Receive Queue 1 Put Pointer)
PCI
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
rv
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
Intel
XScale
®
processor internal bus address offset
+0A00H
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible