====== IF ======
===== if_statement =====
<code vhdl>
[ if _label : ]
    if condition then
        sequence_of_statements
    { elsif condition then
        sequence_of_statements }
    [ else
        sequence_of_statements ]
end if [ if _label ] ;
</code>

===== Parents =====
  * function_statement_part
  * procedure_statement_part
  * process_statement_part

===== Further definitions =====
==== label ====
  * [[.:bnf#identifier]]

==== condition ====
''//boolean// _[[.:bnf#expression]]''

==== sequence_of_statements ====
''{ [[.:bnf#sequential_statement]] }''

===== Examples =====
If //a// has the value //1// then //b// is assigned the value //0// .
<code vhdl>
IF a = '1' THEN
   b := '0' ;
END IF ;
</code>

----

If the value of //a// is bigger than //0// then //b// is assigned the value of //a//, otherwise that of **ABS** ( //a + 1// ).
<code vhdl>
IF a > 0 THEN
   b := a ;
ELSE
   b := ABS ( a + 1 ) ;
END IF ;
</code>

----

This is an example of a complete **IF** - **ELSIF** -loop. The conditions are checked one after the other. When the first match is found the relevant actions are carried out and the **IF** -loop is left.
<code vhdl>
IF val >= 5 AND val < 10 THEN
   int := 7 ;
ELSIF val < 5 THEN
   int := val + func( val + 2 ) ;
ELSIF val < 15 THEN
   int := func( val ) ;
ELSE
   int := 0 ;
END IF ;
</code>