Module path polarity describes when a signal is inverted or not driving propagation between the source and the destination .
+=> positive simple module path polarity
-=> negative simple module path polarity
+*> positive multiple module path polarity
-*> negative multiple module path polarity
The polarity of the module is a description of what happens when a signal is propagated from the source to the destination. There are three possible polarities of the module.
· Unknown polarity
· Positive polarity
· Negative polarity
Positive polarity is specified by the + prefix. When positive polarity is specified, simple rules apply: a rise at the source causes a rise transition at the destination and a fall transition at the source causes the fall transition at the destination. (Example 1)
Negative polarity is specified by the - prefix. When negative polarity is specified, the rules applied are similar to those from positive polarity. However, a rise transition at the source causes fall transition at the destination, and a fall transition at the source causes a rise transition at the destination. (Example 2)
When no prefix is specified with => or *> operators, it means that unknown polarity is to be used by default. In this case a rise transition at the source may cause a rise, a fall, or no transition at the destination. The same rule applies for the fall transition. (Example 3)
(DataIn +=> DataOut) = DataIn_to_DataOut ;
(DataIn +*> DataOut) = DataIn_to_DataOut ;
(DataIn -=> DataOut) = DataIn_to_DataOut ;
(DataIn -*> DataOut) = DataIn_to_DataOut ;
(DataIn => DataOut) = DataIn_to_DataOut ;
(DataIn *> DataOut) = DataIn_to_DataOut ;
Default unknown polarity.
· By default, unknown polarity is specified.
· Module path polarity is used by a timing analysis tool and is ignored by the simulator.