6.6 Attribute names

6.6.1 Definitions

attribute_name ::=
    prefix [ signature ] ' attribute_designator [ ( expression ) ]

6.6.2 Examples

register'left(1)

The left element of the first dimension of the one-
or multi-dimensional array register is addressed.

output'fanout

The attribute fanout provides the number
of signals driven by output .

clk'delayed( 5 ns )

The signal clk, delayed by 5ns, is addressed.

SIGNAL a1: bit_vector(3 DOWNTO 0) ;
...
PROCESS (a)
   BEGIN
   z<= "0000" :
   FOR i in 0 TO 3 LOOP
      IF (a = i) THEN
         z(i) <= '1' ;
      END IF ;
   END LOOP ;
END PROCESS ;
...

By using predefined attributes the loop-instruction
can be written in a different way as well:

FOR i IN a1'LOW TO a1'HIGH

FOR i IN a1'RIGHT TO a1'LEFT

FOR i IN a1'REVERSE_RANGE

FOR i IN a1'RANGE