Index: obj_subc_hash.c
===================================================================
--- obj_subc_hash.c	(nonexistent)
+++ obj_subc_hash.c	(revision 14724)
@@ -0,0 +1,76 @@
+/*
+ *                            COPYRIGHT
+ *
+ *  pcb-rnd, interactive printed circuit board design
+ *  Copyright (C) 2018 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ *  Contact:
+ *    Project page: http://repo.hu/projects/pcb-rnd
+ *    lead developer: email to pcb-rnd (at) igor2.repo.hu
+ *    mailing list: pcb-rnd (at) list.repo.hu (send "subscribe")
+ */
+
+#include "config.h"
+
+#include "data.h"
+#include "layer.h"
+#include "obj_subc.h"
+#include "obj_arc.h"
+#include "obj_line.h"
+#include "obj_text.h"
+#include "obj_poly.h"
+#include "obj_pstk.h"
+
+pcb_bool_t pcb_subc_eq(const pcb_subc_t *sc1, const pcb_subc_t *sc2)
+{
+	return pcb_false;
+}
+
+unsigned int pcb_subc_hash(const pcb_subc_t *sc)
+{
+	unsigned int hash = 0;
+	int lid;
+	pcb_host_trans_t tr;
+
+	pcb_subc_get_host_trans(sc, &tr);
+
+	for(lid = 0; lid < sc->data->LayerN; lid++) {
+		pcb_layer_t *ly = &sc->data->Layer[lid];
+		gdl_iterator_t it;
+		pcb_line_t *l;
+		pcb_arc_t *a;
+		pcb_text_t *t;
+		pcb_poly_t *p;
+
+#warning TODO: hash layers
+
+		linelist_foreach(&ly->Arc, &it, a)
+			hash ^= pcb_arc_hash(&tr, a);
+
+		linelist_foreach(&ly->Line, &it, l)
+			hash ^= pcb_line_hash(&tr, l);
+
+		textlist_foreach(&ly->Text, &it, t)
+			hash ^= pcb_text_hash(&tr, t);
+
+		polylist_foreach(&ly->Polygon, &it, p)
+			hash ^= pcb_poly_hash(&tr, p);
+	}
+
+	return hash;
+}
+