Incrementing Bursts
The interconnect converts all input
INCR
bursts that complete within a single output data width to an
INCR1
burst of the minimum
SIZE
possible, and packs all
INCR
bursts into
INCR
bursts of the optimal
size possible for maximum data throughout.
Wrapping Bursts
All
WRAP
bursts are either passed through unconverted as
WRAP
bursts, or converted to one or two
INCR
bursts of the output bus. The interconnect converts input
WRAP
bursts that have a total payload less than
the output data width to a single
INCR
burst.
Fixed Bursts
All
FIXED
bursts pass through unconverted.
Bypass Merge
If the programmable bit
bypass_merge
is enabled, the interconnect does not alter any transactions that
could pass through legally without alteration. Bypass merge is accessible through the GPV registers and is
only accessible to secure masters.
Downsizing Data Width Function
The downsizing function reduces the data width of a transaction to match the optimal data width at the
destination. Downsizing does not merge multiple-transaction data narrower than the destination bus if the
transactions are marked as noncacheable.
The downsizing function reduces the data width by the following ratios:
• 2:1
• 4:1
Incrementing Bursts
The interconnect converts
INCR
bursts that fall within the maximum payload size of the output data bus
to a single
INCR
burst. It converts
INCR
bursts that are greater than the maximum payload size of the output
data bus to multiple
INCR
bursts.
INCR
bursts with a size that matches the output data width pass through unconverted.
The interconnect packs
INCR
bursts with a
SIZE
smaller than the output data width to match the output
width whenever possible, using the upsizing function.
Related Information
on page 4-17
Wrapping Bursts
The interconnect always converts
WRAP
bursts to
WRAP
bursts of twice the length, up to the output data
width maximum size of
WRAP16
, and treats the
WRAP
burst as two
INCR
bursts that can each be converted
into one or more
INCR
bursts.
Interconnect
Altera Corporation
cv_54004
Incrementing Bursts
4-18
2013.12.30