etisserant@0: (*
msousa@274:  *  matiec - a compiler for the programming languages defined in IEC 61131-3
etisserant@0:  *
msousa@274:  *  Copyright (C) 2011  Mario de Sousa (msousa@fe.up.pt)
etisserant@0:  *
msousa@274:  *  This program is free software: you can redistribute it and/or modify
msousa@274:  *  it under the terms of the GNU General Public License as published by
msousa@274:  *  the Free Software Foundation, either version 3 of the License, or
msousa@274:  *  (at your option) any later version.
msousa@274:  *
msousa@274:  *  This program is distributed in the hope that it will be useful,
msousa@274:  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
msousa@274:  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
msousa@274:  *  GNU General Public License for more details.
msousa@274:  *
msousa@274:  *  You should have received a copy of the GNU General Public License
msousa@274:  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
msousa@274:  *
etisserant@0:  *
etisserant@0:  * This code is made available on the understanding that it will not be
etisserant@0:  * used in safety-critical situations without a full and competent review.
etisserant@0:  *)
etisserant@0: 
etisserant@0: (*
msousa@274:  * An IEC 61131-3 compiler.
etisserant@0:  *
etisserant@0:  * Based on the
etisserant@0:  * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
etisserant@0:  *
etisserant@0:  *)
etisserant@0: 
etisserant@0: 
etisserant@0: (*
etisserant@0:  * This is part of the library conatining the functions
etisserant@0:  * and function blocks defined in the standard.
etisserant@0:  *
etisserant@0:  * SR and RS function blocks
etisserant@0:  * -------------------------
etisserant@0:  *)
etisserant@0: 
msousa@274: (* The standard defines the SR FB thus: 
msousa@274: 
msousa@274:                   +-----+
msousa@274: S1----------------| >=1 |---Q1
msousa@274:          +---+    |     |
msousa@274:  R------O| & |----|     |
msousa@274:  Q1------|   |    |     |
msousa@274:          +---+    +-----+
msousa@274: *)
etisserant@0: 
etisserant@0: FUNCTION_BLOCK SR
etisserant@0:   VAR_INPUT
msousa@274:     S1, R : BOOL;
etisserant@0:   END_VAR
etisserant@0:   VAR_OUTPUT
etisserant@0:     Q1 : BOOL;
etisserant@0:   END_VAR
msousa@274:   Q1 := S1 OR ((NOT R) AND Q1);
msousa@274: END_FUNCTION_BLOCK
etisserant@0: 
msousa@274: 
msousa@274: (* The standard defines the RS FB thus: 
msousa@274:                    +---+
msousa@274: R1----------------O| & |---Q1
msousa@274:         +-----+    |   |
msousa@274: S-------| >=1 |----|   |
msousa@274: Q1------|     |    |   |
msousa@274:         +-----+    +---+
msousa@274: *)
etisserant@0: 
etisserant@0: FUNCTION_BLOCK RS
etisserant@0:   VAR_INPUT
msousa@274:     S, R1 : BOOL;
etisserant@0:   END_VAR
etisserant@0:   VAR_OUTPUT
etisserant@0:     Q1 : BOOL;
etisserant@0:   END_VAR
msousa@274:   Q1 := (NOT R1) AND (S OR Q1);
etisserant@0: END_FUNCTION_BLOCK