(*
 * (c) 26 Feb 2001 David Campbell
 *
 * Offered to the public under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
 * Public License for more details.
 *
 * This code is made available on the understanding that it will not be
 * used in safety-critical situations without a full and competent review.
 *)

(*
 * An IEC 61131-3 IL and ST compiler.
 *
 * Based on the
 * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
 *
 *)


(*
 * This is part of the library conatining the functions
 * and function blocks defined in the standard.
 *
 * SR and RS function blocks
 * -------------------------
 *)


FUNCTION_BLOCK SR
  VAR_INPUT
    S1 : BOOL;
    R  : BOOL;
  END_VAR
  VAR_OUTPUT
    Q1 : BOOL;
  END_VAR
  VAR
    Q_INTERNAL : BOOL;
  END_VAR

  Q_INTERNAL := S1 OR ( Q_INTERNAL AND (NOT R));
  Q1 := Q_INTERNAL;
END_FUNCTION_BLOCK

FUNCTION_BLOCK RS
  VAR_INPUT
    S : BOOL;
    R1 : BOOL;
  END_VAR
  VAR_OUTPUT
    Q1 : BOOL;
  END_VAR
  VAR
    Q_INTERNAL : BOOL;
  END_VAR

  Q_INTERNAL := (NOT R1) AND (S OR Q_INTERNAL);
  Q1 := Q_INTERNAL;
END_FUNCTION_BLOCK