ARM AMBA NIC-301 - Manual (Page 28)

Functional Description
ARM DDI 0397G Copyright © 2006-2010 ARM. All rights reserved. 2-13
ID031010 Non-Confidential
INCR bursts
The network converts all input INCR bursts that complete within a single output data width into
an INCR1 of the minimum SIZE possible, and it packs all INCR bursts into INCR bursts of the
optimum size possible. Table 2-3 shows how the network converts INCR bursts when it upsizes
them.
WRAP bursts
All WRAP bursts are either passed through unconverted as WRAP bursts, or converted to one
or two INCR bursts of the output bus. Table 2-4 shows how the network converts WRAP bursts
when it upsizes them from 64-bit to 128-bit, that is, a ratio of 1:2.
Note
The network converts input WRAP bursts with a total payload that is less than the output data
width to a single INCR.
Fixed bursts
All FIXED bursts pass through unconverted.
Bypass merge
You can configure the upsizer function to have a programmable bit named
bypass_merge
. If
bypass_merge is asserted, the network does not alter any transactions that could pass through
legally without alteration.
Table 2-3 Conversion of INCR bursts by the upsize function
INCR burst type Converted to
64-bit INCR1 Passes through unconverted
64-bit aligned INCR2 INCR1
8-bit aligned INCR8 INCR1, 128-bit
8-bit unaligned, byte address 1, 2, or 3, INCR5 INCR1, 128-bit
8-bit unaligned, byte address 4, 5, 6, or 7, INCR5 INCR2, 64-bit
64-bit unaligned INCR2 Passes through unconverted
64-bit aligned INCR4 INCR2
64-bit unaligned INCR4 Sparse INCR3
Table 2-4 Conversion of WRAP bursts by the upsize function
WRAP burst type Converted to
64-bit aligned WRAP2 INCR1
64-bit aligned WRAP4 WRAP2
64-bit unaligned WRAP4 Depending on the address:
•
INCR2 + INCR1
• INCR1 + INCR2