1 (*

     2  * (c) 2011 Edouard Tisserant

     3  *

     4  * Fake semaphore support, for non preemptive implementation.

     5  *

     6  *)

     7 

     8 

     9 FUNCTION_BLOCK SEMA

    10   VAR_INPUT

    11     CLAIM : BOOL;

    12     RELEASE : BOOL;

    13   END_VAR

    14   VAR_OUTPUT

    15     BUSY : BOOL;

    16   END_VAR

    17   VAR

    18     Q_INTERNAL : BOOL;

    19   END_VAR

    20 

    21   Q_INTERNAL := CLAIM OR ( Q_INTERNAL AND (NOT RELEASE));

    22   BUSY := Q_INTERNAL;

    23 

    24 END_FUNCTION_BLOCK

    25