Index: src/list_element.c
===================================================================
--- src/list_element.c	(revision 2655)
+++ src/list_element.c	(revision 2656)
@@ -26,3 +26,9 @@
 #define TDL_DONT_UNDEF
 #include "list_element.h"
 #include <genlist/gentdlist_impl.c>
+
+long pcb_element_hash(const ElementType *e)
+{
+#warning TODO: hash the content, ignore the name
+	return strhash(e->Name[0].TextString);
+}
Index: src/list_element.h
===================================================================
--- src/list_element.h	(revision 2655)
+++ src/list_element.h	(revision 2656)
@@ -23,6 +23,9 @@
 #ifndef LIST_ELEMENT_H
 #define LIST_ELEMENT_H
 
+#include <genht/hash.h>
+#include <genht/htip.h>
+
 /* List of Lines */
 #define TDL(x)      elementlist_ ## x
 #define TDL_LIST_T  elementlist_t
@@ -34,7 +37,34 @@
 #define elementlist_foreach(list, iterator, loop_elem) \
 	gdl_foreach_((&((list)->lst)), (iterator), (loop_elem))
 
+/* Calculate a hash value using the content of the element. The hash value
+   represents the actual content of an element */
+long pcb_element_hash(const ElementType *e);
 
+#define elementlist_dedup_initializer(state) htip_t *state = NULL;
+
+#define elementlist_dedup_skip(state, loop_elem) \
+switch(1) { \
+	case 1: { \
+		long element_hash; \
+		if (state == NULL) \
+			state = htip_alloc(longhash, longkeyeq); \
+		element_hash = pcb_element_hash(loop_elem); \
+		if (htip_has(state, element_hash)) \
+			continue; \
+		htip_set(state, element_hash, loop_elem); \
+	} \
+}
+
+#define elementlist_dedup_free(state) \
+	do { \
+		if (state != NULL) { \
+			htip_free(state); \
+			state = NULL; \
+		} \
+	} while(0)
+
+
 #ifndef LIST_ELEMENT_NOINSTANT
 #include <genlist/gentdlist_impl.h>
 #include <genlist/gentdlist_undef.h>