+/*
+typedef struct link_s
+{
+ struct link_s *prev, *next;
+} link_t;
+*/
+
+
+void ClearLink (link_t *l);
+void RemoveLink (link_t *l);
+void InsertLinkBefore (link_t *l, link_t *before);
+void InsertLinkAfter (link_t *l, link_t *after);
+
+// (type *)STRUCT_FROM_LINK(link_t *link, type, member)
+// ent = STRUCT_FROM_LINK(link,entity_t,order)
+// FIXME: remove this mess!
+//#define STRUCT_FROM_LINK(l,t,m) ((t *)((byte *)l - (int)&(((t *)0)->m)))
+
+#define EDICT_FROM_AREA(l) ((edict_t *)((byte *)l - (int)&(((edict_t *)0)->area)))
+
+//============================================================================
+
+// ClearLink is used for new headnodes
+void ClearLink (link_t *l)
+{
+ l->prev = l->next = l;
+}
+
+void RemoveLink (link_t *l)
+{
+ l->next->prev = l->prev;
+ l->prev->next = l->next;
+}
+
+void InsertLinkBefore (link_t *l, link_t *before)
+{
+ l->next = before;
+ l->prev = before->prev;
+ l->prev->next = l;
+ l->next->prev = l;
+}
+void InsertLinkAfter (link_t *l, link_t *after)
+{
+ l->next = after->next;
+ l->prev = after;
+ l->prev->next = l;
+ l->next->prev = l;
+}
+