--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/newgrf_commons.cpp	Wed Jun 13 11:45:14 2007 +0000
@@ -0,0 +1,150 @@
+/* $Id$ */
+
+/** @file newgrf_commons.cpp Implementation of the class OverrideManagerBase
+ * and its descendance, present and futur
+ */
+
+#include "stdafx.h"
+#include "openttd.h"
+#include "town.h"
+#include "industry.h"
+#include "newgrf.h"
+#include "newgrf_commons.h"
+
+/** Constructor of generic class
+ * @param offset end of original data for this entity. i.e: houses = 110
+ * @param maximum of entities this manager can deal with. i.e: houses = 512
+ * @param invalid is the ID used to identify an invalid entity id
+ */
+OverrideManagerBase::OverrideManagerBase(uint16 offset, uint16 maximum, uint16 invalid)
+{
+	max_offset = offset;
+	max_new_entities = maximum;
+	invalid_ID = invalid;
+
+	mapping_ID = CallocT<EntityIDMapping>(max_new_entities);
+	entity_overrides = MallocT<uint16>(max_offset);
+	memset(entity_overrides, invalid, sizeof(entity_overrides));
+}
+
+/** Destructor of the generic class.
+ * Frees allocated memory of constructor
+ */
+OverrideManagerBase::~OverrideManagerBase()
+{
+	free(mapping_ID);
+	free(entity_overrides);
+}
+
+/** Since the entity IDs defined by the GRF file does not necessarily correlate
+ * to those used by the game, the IDs used for overriding old entities must be
+ * translated when the entity spec is set.
+ * @param local_id id in grf file
+ * @param entity_type original entity type
+ */
+void OverrideManagerBase::Add(uint8 local_id, uint entity_type)
+{
+	assert(entity_type < max_offset);
+	entity_overrides[entity_type] = local_id;
+}
+
+/** Resets the mapping, which is used while initializing game */
+void OverrideManagerBase::ResetMapping()
+{
+	memset(mapping_ID, 0, (max_new_entities - 1) * sizeof(EntityIDMapping));
+}
+
+/** Resets the override, which is used while initializing game */
+void OverrideManagerBase::ResetOverride()
+{
+	for (uint16 i = 0; i < max_offset; i++) {
+		entity_overrides[i] = invalid_ID;
+	}
+}
+
+/** Return the ID (if ever available) of a previously inserted entity.
+ * @param grf_local_id ID of this enity withing the grfID
+ * @param grfid ID of the grf file
+ * @return the ID of the candidate, of the Invalid flag item ID
+ */
+uint16 OverrideManagerBase::GetID(uint8 grf_local_id, uint32 grfid)
+{
+	const EntityIDMapping *map;
+
+	for (uint16 id = max_offset; id < max_new_entities; id++) {
+		map = &mapping_ID[id];
+		if (map->entity_id == grf_local_id && map->grfid == grfid) {
+			return id;
+		}
+	}
+	return invalid_ID;
+}
+
+/** Reserves a place in the mapping array for an entity to be installed
+ * @param grf_local_id is an arbitrary id given by the grf's author.  Also known as setid
+ * @param grfid is the id of the grf file itself
+ * @param substitute_id is the original entity from which data is copied for the new one
+ * @return the proper usable slot id, or invalid marker if none is found
+ */
+uint16 OverrideManagerBase::AddEntityID(byte grf_local_id, uint32 grfid, byte substitute_id)
+{
+	uint16 id = this->GetID(grf_local_id, grfid);
+	EntityIDMapping *map;
+
+	/* Look to see if this entity has already been added. This is done
+	 * separately from the loop below in case a GRF has been deleted, and there
+	 * are any gaps in the array.
+	 */
+	if (id != invalid_ID) {
+		return id;
+	}
+
+	/* This entity hasn't been defined before, so give it an ID now. */
+	for (id = max_offset; id < max_new_entities; id++) {
+		map = &mapping_ID[id];
+
+		if (map->entity_id == 0 && map->grfid == 0) {
+			map->entity_id     = grf_local_id;
+			map->grfid         = grfid;
+			map->substitute_id = substitute_id;
+			return id;
+		}
+	}
+
+	return invalid_ID;
+}
+
+/** Gives the substitute of the entity, as specified by the grf file
+ * @param entity_id of the entity being queried
+ * @return mapped id
+ */
+uint16 OverrideManagerBase::GetSubstituteID(byte entity_id)
+{
+	return mapping_ID[entity_id].substitute_id;
+}
+
+/** Install the specs into the HouseSpecs array
+ * It will find itself the proper slot onwhich it will go
+ * @param hs HouseSpec read from the grf file, ready for inclusion
+ */
+void HouseOverrideManager::SetEntitySpec(const HouseSpec *hs)
+{
+	HouseID house_id = this->AddEntityID(hs->local_id, hs->grffile->grfid, hs->substitute_id);
+
+	if (house_id == invalid_ID) {
+		grfmsg(1, "House.SetEntitySpec: Too many houses allocated. Ignoring.");
+		return;
+	}
+
+	memcpy(&_house_specs[house_id], hs, sizeof(*hs));
+
+	/* Now add the overrides. */
+	for (int i = 0; i != max_offset; i++) {
+		HouseSpec *overridden_hs = GetHouseSpecs(i);
+
+		if (entity_overrides[i] != hs->local_id) continue;
+
+		overridden_hs->override = house_id;
+		entity_overrides[i] = invalid_ID;
+	}
+}