Expression
An expression calculates a value from a set of operators, names, literal
values and sub-expressions. A static expression is an expression whose
value can be calculated during compilation or elaboration.
Syntax
{either}
Expression Operator Expression
Operator Expression
(Expression)
Name
Number
PhysicalLiteral
Character
String
Aggregate
QualifiedExpression
New
FunctionCall
Placement
PACKAGE Pack IS
... 
END PACKAGE Pack;
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PACKAGE BODY Pack IS
...
END PACKAGE BODY Pack;
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Blk:BLOCK
...
BEGIN
...
END BLOCK Blk;
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ENTITY Ent IS
...
BEGIN
...
END ENTITY Ent;
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ARCHITECTURE Arc OF Ent IS
...
BEGIN
...
END ARCHITECTURE Arc;
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CONFIGURATION Conf OF Ent IS
...
END CONFIGURATION Conf;
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Proc:PROCESS(...)
...
BEGIN
...
END PROCESS Proc;
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PROCEDURE P(...) IS
...
BEGIN
...
END PROCEDURE P;
|
FUNCTION F(...) RETURN Tp IS
...
BEGIN
...
END FUNCTION F;
|
Rules
Operators are evaluated in the following order:
1st: ** abs not
2nd: * / mod rem
3rd: + - &
4th: sll srl sla sra rol ror
5th: = /= < <= > >=
6th: and or xor nand nor xnor
Example
A + B
not A
(A nand B) nor C
A(7 downto 0) -- name
'0' -- character
(others => '0') -- aggregate
To_integer(V) -- function call
T'(A, B) -- qualified expression
new T
See Also
Operator, Name, Aggregate, New, Qualified Expression
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