lib/sema.txt
author Mario de Sousa <msousa@fe.up.pt>
Sat, 14 Apr 2012 15:19:17 +0100
changeset 504 f8d422b98315
parent 251 5e7457efbb8f
permissions -rw-r--r--
Fix bug by expanding permissible data input of search_var_instance_decl_c
(this will also prepare us for removing search_varfb_instance_type_c in the future)
(*
 * (c) 2011 Edouard Tisserant
 *
 * Fake semaphore support, for non preemptive implementation.
 *
 *)


FUNCTION_BLOCK SEMA
  VAR_INPUT
    CLAIM : BOOL;
    RELEASE : BOOL;
  END_VAR
  VAR_OUTPUT
    BUSY : BOOL;
  END_VAR
  VAR
    Q_INTERNAL : BOOL;
  END_VAR

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

END_FUNCTION_BLOCK