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AR# 530

5.0,5.1 PPR - Possible cause of bad grouping using statements on TIMEGRP symbol

Solution




PROGRAM: PPR

VERSION: 5.0, 5.1

PLATFORM: ALL

SHORT DESCRIPTION:

Forward - referencing TIMEGRP statements cause grouping errors

LONG DESCRIPTION:

PROBLEM:

Users may notice that, when using a TIMEGRP symbol to group symbols, that
the resulting groups are not what they expected, not containing the correct
number of symbols.

CAUSE:

One possible cause of this is the use of forward referencing statements in
TIMEGRP statements. For example, the following three lines could be added
to a TIMEGRP symbol:

A=C
B=FFS:EXCEPT:A
C=RISING:FFS

A references C, and B references A, so therefore both A and B depend on C,
which is not yet defined. The software performs only one 'pass' to resolve
the references, so the A group ends up being defined correctly in this case,
but the B group would actually contain *all* flip-flops, since the A group
is empty when it is resolved.

SOLUTION:

Avoid these type of references in TIMEGRP statements.

AR# 530
Date Created 08/31/2007
Last Updated 03/22/2000
Status Archive
Type ??????