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168 21555 Non-Transparent PCI-to-PCI Bridge User Manual
List of Registers
Table 91. I2O Inbound Post_List Counter
Byte Offsets: 05B:058h
Bit Name R/W Description
15:0 Inbound Post Ctr R/(WS)
When read, returns the number of entries in the Inbound
Post_List.
Decrements by 1 when this location is written from the
secondary interface with any data value if bit [31] of this register
is written with a 0 during the same write. When bit [31] is written
with a 1, the 21555 loads the counter with the value written.
Increments when the Inbound Queue at offset 40h is written
from the primary interface.
Reset value : 0
30:16 Reserved R Reserved. Read only as 0.
31 LD_IPC W1TL(S)
Load Inbound Post_List Counter.
• When written with a 1 at the same time as the Inbound Post
Car bits [15:0], it loads the Inbound Post_List Counter with
the value on s_ad[15:0] during that same write.
• When written with a 0, or if s_cbe_l[3] is 1, decrements the
Inbound Post_List Counter. Reads always return 0.
Table 92. I2O Inbound Free_List Counter
Byte Offsets: 05F:05Ch.
Bit Name R/W Description
15:0 Inbound Free Ctr R/(WS)
When read, returns the number of entries in the Inbound
Free_List.
Increments by 1 when this location is written from the secondary
interface with any data value if bit [31] of this register is written
with a 0 during the same write.
When bit [31] is written with a 1, the 21555 loads the counter
with the value written.
Decrements when the Inbound Queue at offset 40h is read from
the primary interface, except when the counter is zero. The
21555 does not decrement when the counter is 0.
Reset value is 0
30:16 Reserved R Reserved. Read only as 0.
31 LD_IFC W1TL(S)
Load Inbound Free_List Counter.
• When written with a 1 at the same time as the Inbound Free
Ctr bits [15:0], loads the Inbound Free_List Counter with the
value on s_ad[15:0] during that same write.
• When written with a 0, or if s_cbe_l[3] is 1, increments the
Inbound Free_List Counter. Reads always return 0.