AHDL

Logical Operators



The following logical operators can be used in Boolean expressions:

Operator: Example: Description:
!
NOT
!tob
NOT tob
one's complement (prefix inverter)
&
AND
bread & butter
bread AND butter
AND
!&
NAND
a[3..1] !& b[5..3]
a[3..1] NAND b[5..3]
AND inverter
#
OR
trick # treat
trick OR treat
OR
!#
NOR
c[8..5] !# d[7..4]
c[8..5] NOR d[7..4]
OR inverter
$
XOR
foo $ bar
foo XOR bar
exclusive OR
!$
XNOR
x2 !$ x4
x2 XNOR x4
exclusive NOR

Each operator represents a two-input logic gate, except the NOT (!) operator, which is a prefix inverter on a single node. You can use either the name or the symbol to represent a logical operator.

Expressions that use these operators are interpreted differently, depending on whether the operands are single nodes, groups, or numbers. Also, expressions with the NOT operator are interpreted differently from those with other logical operators.

You can name Boolean operators and comparators in AHDL files to make it easy to enter resource assignments and to interpret the Equations Section of the Text-Format Report File (.rpt) or HTML-Format Report File (.htm)). For more information, go to Naming a Boolean Operator or Comparator.


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