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AR# 555

Error es14 or es6: Too many shared D1 product terms


Fitnet issues one of the following errors:

es14:[Error]Too many D1 shared product terms. '<n>' required!

es6:[Error]Too many shared D1 product terms needed for equation '<xxxx>'!
<n> product terms needed but only 4 available. You have either
explicitly specified a D1 signal or an XOR or .T function resolves to
a function containing D1.


Often caused by an XOR7 or XOR8 gate feeding the input to a BUFT, BUFE,
or OBUFE component.

If the enable signal of the buffer cannot be placed onto an FOE, it will
use one of the private product terms in the macrocell. This reduces the
maximum number of product terms available to the D1 signal in that macrocell.
Fitnet still attempts to optimize the XOR gate into the same macrocell,
causing the error.

Place an OPT=OFF attribute on the XOR gate, or break wide XOR gates into
smaller XOR gates.

If using the Synopsys interface, either place a NO_OPT attribute on the
XOR output signal, or specify the following:

dont_use {xc7000/XOR7 xc7000/XOR8}
AR# 555
Date 10/01/2008
Status Archive
Type General Article