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AR# 3766

MAP M1.4: x4kma:312 - The following symbols could not be constrained to a single CLB (Two F-LUT's, an H-LUT, and carry logic).


Keywords: MAP, legal, pack, constrain, CLB

Urgency: Standard

General Description:

This solution record involves one case where the following
error message is encountered during MAP.

ERROR: x4kma:312 - The following symbols could not be
constrained to a single CLB:
CY4 symbol "$1I243" (output signal=C6)
CY4_12 symbol "$1I196" (output signal=$1N232)
FMAP symbol "$1I221" (output signal=S6)
HMAP symbol "$1I345" (output signal=S7)
FMAP symbol "$1I222" (output signal=S)
There are two resources that require the F function
generator. These symbols share the same RLOC attribute value,
which requires them to be mapped to the same CLB.

In this specific case, all three lookup tables and the carry
logic are being utilized. The carry mode is ADDSUB. The CIN
input is driven and also goes to the F-LUT. The carry goes to
the G-LUT. The F-LUT utilizes all four inputs and the output
goes out of the CLB. The G-LUT uses all four inputs. The
H-LUT has all three inputs driven: one comes from the output
of the G-LUT, and the other two from outside the CLB. The
H-LUT output goes out of the CLB.
This looks to be a legal pack.


MAP M1.4 cannot perform this legal CLB pack.
It has been addressed and fixed for the next Core Tools
release, M1.5.
AR# 3766
Date 04/25/2000
Status Archive
Type General Article