Index: trunk/scconfig/Rev.h
===================================================================
--- trunk/scconfig/Rev.h	(revision 8748)
+++ trunk/scconfig/Rev.h	(revision 8749)
@@ -1 +1 @@
-static const int myrev = 8593;
+static const int myrev = 8748;
Index: trunk/scconfig/Rev.tab
===================================================================
--- trunk/scconfig/Rev.tab	(revision 8748)
+++ trunk/scconfig/Rev.tab	(revision 8749)
@@ -1,3 +1,4 @@
+8748	configure	core: new pcb_bool source file
 8593	configure	gtk: new layer selector
 8331	configure	cquote generates C98-safe long strings
 8275	configure	puplug
Index: trunk/src/Makefile.in
===================================================================
--- trunk/src/Makefile.in	(revision 8748)
+++ trunk/src/Makefile.in	(revision 8749)
@@ -106,6 +106,7 @@
 	obj_text.o
 	obj_text_list.o
 	paths.o
+	pcb_bool.o
 	pcb-printf.o
 	plugins.o
 	plug_import.o
Index: trunk/src/pcb_bool.c
===================================================================
--- trunk/src/pcb_bool.c	(nonexistent)
+++ trunk/src/pcb_bool.c	(revision 8749)
@@ -0,0 +1,34 @@
+/*
+ *                            COPYRIGHT
+ *
+ *  pcb-rnd, interactive printed circuit board design
+ *  Copyright (C) 2017 Tibor 'Igor2' Palinkas
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it 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.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include "config.h"
+#include "pcb_bool.h"
+#include "compat_misc.h"
+
+pcb_bool_op_t pcb_str2boolop(const char *s)
+{
+	if (pcb_strcasecmp(s, "set"))       return PCB_BOOL_SET;
+	if (pcb_strcasecmp(s, "clear"))     return PCB_BOOL_CLEAR;
+	if (pcb_strcasecmp(s, "toggle"))    return PCB_BOOL_TOGGLE;
+	if (pcb_strcasecmp(s, "preserve"))  return PCB_BOOL_PRESERVE;
+	return PCB_BOOL_INVALID;
+}
Index: trunk/src/pcb_bool.h
===================================================================
--- trunk/src/pcb_bool.h	(revision 8748)
+++ trunk/src/pcb_bool.h	(revision 8749)
@@ -2,8 +2,8 @@
  *                            COPYRIGHT
  *
  *  pcb-rnd, interactive printed circuit board design
- *  Copyright (C) 2016 Tibor 'Igor2' Palinkas
- * 
+ *  Copyright (C) 2016, 2017 Tibor 'Igor2' Palinkas
+ *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
@@ -35,7 +35,8 @@
 	PCB_BOOL_CLEAR = 0,
 	PCB_BOOL_SET = 1,
 	PCB_BOOL_TOGGLE = -1,
-	PCB_BOOL_PRESERVE = -2
+	PCB_BOOL_PRESERVE = -2,
+	PCB_BOOL_INVALID = -8
 } pcb_bool_op_t;
 
 /* changes the value of pcb_bool dst as requested by pcb_bool_op_t op
@@ -46,6 +47,7 @@
 		case PCB_BOOL_CLEAR:   (dst) = 0; break; \
 		case PCB_BOOL_SET:     (dst) = 1; break; \
 		case PCB_BOOL_TOGGLE:  (dst) = !(dst); break; \
+		case PCB_BOOL_INVALID: \
 		case PCB_BOOL_PRESERVE: break; \
 	} \
 } while(0)