.. _Profiler:

========
Profiler
========

Sometimes it is useful to watch a word working. The Tracer
gives many informations, which may be confusing or un-usable at all. The number of calls
of a given word can be more instructive. This is the time for the profiler utility.

.. code-block:: forth

 variable profiling?
 : profile:on -1 profiling? ! ;
 : profile:off 0 profiling? ! ;

 : profiler profiling? @ if 1 swap +! else drop then ;
 \ re-define colon
 : : :
   here 2 allot postpone literal postpone profiler
 ;

 \ get the address of the profiling data.
 : xt>prf ( xt -- addr )
  cell+ @i
 ;

After loading it into the controller, every colon word gets a counter
(1 cell) which is incremented every time the word is called. Since this cell
can be used like any variable, it can be reset any time as well.

.. code-block:: console

 > : foo 1 ;
  ok
 > profiler:on
  ok
 > ' foo xt>prf @ .
 0 ok
 > foo
  ok
 > ' foo xt>prf @ .
 1 ok
 > 0 ' foo xt>prf !
 ok
 >