====== Wait ======
===== wait_statement =====
<code vhdl>[ label : ] wait [ sensitivity_clause ] [ condition_clause ] [ timeout_clause ] ;</code>

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

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

==== sensitivity_clause ====
''**on** [[.:bnf#sensitivity_list]]''

==== condition_clause ====
''**until** [[.:bnf#condition]]''

==== timeout_clause ====
''**for** //time// _[[.:bnf#expression]]''

===== Comments =====
The WAIT-statement must not be used within a function or procedure which itself is called within a function.

The WAIT-statement must not be called by a process which possesses a sensitivity list.

In general the WAIT-statement is ,sensitive" to all signals used within the statement, except a sensitivity list is used (like in a WAIT ON-statement like in the last example).

In a postponed process the condition in a WAIT statement may already be false at the actual time (last delta cycle) when the process execution is resumed.

===== Examples =====
The process is permanently interrupted.
<code vhdl>WAIT ;</code>

----

The process is interrupted for 5 ns.
<code vhdl>WAIT FOR 5 ns ;</code>

----

The process is interrupted until the value of one of the two signals changes.
<code vhdl>WAIT ON sig_1, sig_2 ;</code>

----

The process is interrupted until the value of //clock// is 1.
<code vhdl>WAIT UNTIL clock = '1' ;</code>

----

The process is interrupted until the value of //data = good// or 25 ns have passed.
<code vhdl>WAIT UNTIL data = good FOR 25 ns ;</code>

----

Initially one waits for the signals sig_1, sig_2 and sig_3 to change; if clock is 1 the process is resumed otherwise not; the process is suspended for at most 25ns.
<code vhdl>
WAIT ON sig_1, sig_2, sig_3
      UNTIL clock = '1' FOR 25 ns ;
</code>