CS5920 datasheet(79/160 Pages) AMCC

79 / 160 page

S5920 – PCI Product

Revision 1.01 – November 28, 2005

AMCC Confidential and Proprietary

DS1596

Data Book

Table 45. Mailbox Empty/Full Status Register

Bit

Description

31:28

Add-On Outgoing Mailbox Status. This field indicates which byte of the outgoing mailbox register has been writ-

ten by the Add-On interface but has not yet been read by the PCI bus. Each bit location corresponds to a spe-

cific byte within the outgoing mailbox. A value of 1 for each bit signifies that the specified mailbox byte is full, and

a value of 0 signifies empty. The mapping of these status bits to bytes within the mailbox is as follows:

Bit 31 = Outgoing mailbox byte 3

Bit 30 = Outgoing mailbox byte 2

Bit 29 = Outgoing mailbox byte 1

Bit 28 = Outgoing mailbox byte 0

15:12

Add-On Incoming Mailbox Status. This field indicates which byte of the incoming mailbox register has been writ-

ten by the PCI bus interface but has not yet been read by the Add-On bus. Each bit location corresponds to a

specific byte within the incoming mailbox. A value of 1 for each bit signifies that the specified mailbox byte is full,

and a value of 0 signifies empty. The mapping of these status bits to bytes is as follows:

Bit 15 = Incoming mailbox byte 3

Bit 14 = Incoming mailbox byte 2

Bit 13 = Incoming mailbox byte 1

Bit 12 = Incoming mailbox byte 0

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