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).

Description


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.

Solution


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