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AR# 3036

M1.3 Map - Map will not push buffer (or logic optimized to buffer) forward into closed FMAP (MAP=PUC or PLC)

説明

Map will not push buffer (or logic optimized to buffer)
forward into closed FMAP (MAP=PUC).The result is an extra
level of logic as a LUT is used to implement the buffer.
In additionto the extra level of logic, sub-optimal placement
and routing has been reported related to this issue.

Reference # 101674

ソリューション

Change request 101674 has been logged to request buffer
pushing into closed FMAPs for future releases. Meanwhile,
this problem can be worked around by globally opening all
FMAPs in the design using the following constraint in the
.ncf file:

inst "$*" MAP=PUO;

This constraint will not work in the .ucf file because a
"CLOSED" flag is already set for the FMAP by the time the
MAP attribute is overridden by the .ucf file.

The .ncf file is processed during netlist translation
(edif2ngd, xnf2ngd, etc), so this process needs to be
re-run to implement the change. To do this, create a .ncf
file with the same name as the netlist, remove the .ngo
file with the same name, thenre-run the mapping process.

NOTE: When doing wild card matching of instances in .ncf/.ucf
files, it is important to note that "*" will not match strings
beginning with "$" or cross "/" hierarchy dividers. For example,
to match the strings $1I0/xyz and $1I0/$1I1 requires two matching
strings in the .ncf file:

inst "$*/*" MAP=PUO;
inst "$*/$*" MAP=PUO;

To match all possible cases, the following strings are needed:

inst "$*" MAP=PUO;
inst "*" MAP=PUO;
inst "*/*" MAP=PUO;
inst "*/$*" MAP=PUO;

This gets more complicated as the number of hierarchy levels increases.
It may be easier to do a string substitution in the input netlist,
replacing "MAP=PUC" with "MAP=PUO".
AR# 3036
作成日 11/04/1997
最終更新日 11/19/1998
ステータス アーカイブ
タイプ 一般