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88 Software Developer’s Manual
PCI Local Bus Interface
Figure 4-4. Master Write Command Usage Algorithm
4.3.1.1 MWI Bursts
•
If there is at least one cache line of data remaining, then the Ethernet controller continues the
MWI burst.
• If there is not at least one cache line of data remaining, then the Ethernet controller terminates
the transaction on the boundary, re-acquires the bus, and issues a MW command for the
remainder of data.
• If the transaction is terminated prematurely due to a target disconnect or latency time-out, the
Ethernet controller re-evaluates command usage based on the new start address and the
amount of remaining data.
!Aligned || (Aligned && (Count < CLS)) || !MWI_Enable
IDLE
Write Command
Determination
MW
Burst
MWI
Burst*
Terminate
Transaction
MWI
Boundary
Evaluation
Boundary || Terminate
Aligned && (Count >= CLS)
Cnt_Rmn = 0
Cnt_Rmn = 0
!MWI_Enable ||
(!Aligned || Cnt_Rmn < CLS)
M
WI_Enable &&
d
&& Cnt_Rmn >= CLS)
Cnt_Rmn
= Remaining data for XFR
CLS
= Cache line size
Boundary
= At cache line boundary?
Aligned
= Address aligned to cache line boundar
y
Count
= Amount of data for XFR
Wr_Req || (Cnt_Rmn != 0)
Wr_Req
= Initial request for master write
*
Either the initiation or continuation of the MWI Burst
Terminate
Terminate
= Target disconnect or latency timer e
x