--- a/projects/openttd.vcproj	Sat Sep 22 00:59:27 2007 +0000
+++ b/projects/openttd.vcproj	Sat Sep 22 12:59:43 2007 +0000
@@ -571,6 +571,9 @@
 				RelativePath=".\..\src\newgrf_station.h">
 			</File>
 			<File
+				RelativePath=".\..\src\newgrf_storage.h">
+			</File>
+			<File
 				RelativePath=".\..\src\newgrf_text.h">
 			</File>
 			<File
@@ -1122,6 +1125,9 @@
 				RelativePath=".\..\src\newgrf_station.cpp">
 			</File>
 			<File
+				RelativePath=".\..\src\newgrf_storage.cpp">
+			</File>
+			<File
 				RelativePath=".\..\src\newgrf_text.cpp">
 			</File>
 			<File

--- a/projects/openttd_vs80.vcproj	Sat Sep 22 00:59:27 2007 +0000
+++ b/projects/openttd_vs80.vcproj	Sat Sep 22 12:59:43 2007 +0000
@@ -992,6 +992,10 @@
 				>
 			</File>
 			<File
+				RelativePath=".\..\src\newgrf_storage.h"
+				>
+			</File>
+			<File
 				RelativePath=".\..\src\newgrf_text.h"
 				>
 			</File>
@@ -1716,6 +1720,10 @@
 				>
 			</File>
 			<File
+				RelativePath=".\..\src\newgrf_storage.cpp"
+				>
+			</File>
+			<File
 				RelativePath=".\..\src\newgrf_text.cpp"
 				>
 			</File>

--- a/source.list	Sat Sep 22 00:59:27 2007 +0000
+++ b/source.list	Sat Sep 22 12:59:43 2007 +0000
@@ -156,6 +156,7 @@
 newgrf_sound.h
 newgrf_spritegroup.h
 newgrf_station.h
+newgrf_storage.h
 newgrf_text.h
 newgrf_town.h
 newgrf_townname.h
@@ -347,6 +348,7 @@
 newgrf_sound.cpp
 newgrf_spritegroup.cpp
 newgrf_station.cpp
+newgrf_storage.cpp
 newgrf_text.cpp
 newgrf_town.cpp
 newgrf_townname.cpp

--- a/src/command.cpp	Sat Sep 22 00:59:27 2007 +0000
+++ b/src/command.cpp	Sat Sep 22 12:59:43 2007 +0000
@@ -15,6 +15,7 @@
 #include "network/network.h"
 #include "variables.h"
 #include "genworld.h"
+#include "newgrf_storage.h"
 
 const char *_cmd_text = NULL;
 
@@ -573,6 +574,7 @@
 
 		_docommand_recursive = 0;
 		_cmd_text = NULL;
+		ClearStorageChanges(false);
 		return false;
 	}
 
@@ -603,6 +605,7 @@
 		if (_network_dedicated || (_network_server && pbck == PLAYER_SPECTATOR)) _local_player = pbck;
 		_docommand_recursive = 0;
 		_cmd_text = NULL;
+		ClearStorageChanges(false);
 		return true;
 	}
 #endif /* ENABLE_NETWORK */
@@ -643,6 +646,7 @@
 
 	if (callback) callback(true, tile, p1, p2);
 	_cmd_text = NULL;
+	ClearStorageChanges(true);
 	return true;
 
 show_error:
@@ -656,6 +660,7 @@
 
 	if (callback) callback(false, tile, p1, p2);
 	_cmd_text = NULL;
+	ClearStorageChanges(false);
 	return false;
 }
 

--- a/src/newgrf_spritegroup.cpp	Sat Sep 22 00:59:27 2007 +0000
+++ b/src/newgrf_spritegroup.cpp	Sat Sep 22 12:59:43 2007 +0000
@@ -76,7 +76,7 @@
 	_spritegroup_count = 0;
 }
 
-uint32 _temp_store[0x110];
+TemporaryStorageArray<uint, 0x110> _temp_store;
 
 
 static inline uint32 GetVariable(const ResolverObject *object, byte variable, byte parameter, bool *available)
@@ -98,7 +98,7 @@
 		case 0x1C: return object->last_value;
 		case 0x20: return _opt.landscape == LT_ARCTIC ? GetSnowLine() : 0xFF;
 
-		case 0x7D: return _temp_store[parameter];
+		case 0x7D: return _temp_store.Get(parameter);
 
 		/* Not a common variable, so evalute the feature specific variables */
 		default: return object->GetVariable(object, variable, parameter, available);
@@ -137,9 +137,7 @@
 		case DSGA_OP_AND:  return last_value & value;
 		case DSGA_OP_OR:   return last_value | value;
 		case DSGA_OP_XOR:  return last_value ^ value;
-		case DSGA_OP_STO:
-			if (value < lengthof(_temp_store)) _temp_store[value] = last_value;
-			return last_value;
+		case DSGA_OP_STO:  _temp_store.Store(value, last_value); return last_value;
 		case DSGA_OP_RST:  return value;
 		default:           return value;
 	}
@@ -162,7 +160,7 @@
 		bool available = true;
 		if (adjust->variable == 0x7E) {
 			ResolverObject subobject = *object;
-			const SpriteGroup *subgroup = Resolve(adjust->subroutine, &subobject, false);
+			const SpriteGroup *subgroup = Resolve(adjust->subroutine, &subobject);
 			if (subgroup == NULL || subgroup->type != SGT_CALLBACK) {
 				value = CALLBACK_FAILED;
 			} else {
@@ -175,7 +173,7 @@
 		if (!available) {
 			/* Unsupported property: skip further processing and return either
 			 * the group from the first range or the default group. */
-			return Resolve(group->g.determ.num_ranges > 0 ? group->g.determ.ranges[0].group : group->g.determ.default_group, object, false);
+			return Resolve(group->g.determ.num_ranges > 0 ? group->g.determ.ranges[0].group : group->g.determ.default_group, object);
 		}
 
 		switch (group->g.determ.size) {
@@ -216,11 +214,11 @@
 
 	for (i = 0; i < group->g.determ.num_ranges; i++) {
 		if (group->g.determ.ranges[i].low <= value && value <= group->g.determ.ranges[i].high) {
-			return Resolve(group->g.determ.ranges[i].group, object, false);
+			return Resolve(group->g.determ.ranges[i].group, object);
 		}
 	}
 
-	return Resolve(group->g.determ.default_group, object, false);
+	return Resolve(group->g.determ.default_group, object);
 }
 
 
@@ -254,19 +252,16 @@
 	mask  = (group->g.random.num_groups - 1) << group->g.random.lowest_randbit;
 	index = (object->GetRandomBits(object) & mask) >> group->g.random.lowest_randbit;
 
-	return Resolve(group->g.random.groups[index], object, false);
+	return Resolve(group->g.random.groups[index], object);
 }
 
 
 /* ResolverObject (re)entry point */
-const SpriteGroup *Resolve(const SpriteGroup *group, ResolverObject *object, bool first_call)
+const SpriteGroup *Resolve(const SpriteGroup *group, ResolverObject *object)
 {
 	/* We're called even if there is no group, so quietly return nothing */
 	if (group == NULL) return NULL;
 
-	/* Zero the temporary storage to make sure there are no desyncs */
-	if (first_call) memset(_temp_store, 0, sizeof(_temp_store));
-
 	switch (group->type) {
 		case SGT_REAL:          return object->ResolveReal(object, group);
 		case SGT_DETERMINISTIC: return ResolveVariable(group, object);

--- a/src/newgrf_spritegroup.h	Sat Sep 22 00:59:27 2007 +0000
+++ b/src/newgrf_spritegroup.h	Sat Sep 22 12:59:43 2007 +0000
@@ -7,6 +7,7 @@
 
 #include "town.h"
 #include "industry.h"
+#include "newgrf_storage.h"
 
 /**
  * Gets the value of a so-called newgrf "register".
@@ -16,9 +17,8 @@
  */
 static inline uint32 GetRegister(uint i)
 {
-	assert(i < 0x110);
-	extern uint32 _temp_store[0x110];
-	return _temp_store[i];
+	extern TemporaryStorageArray<uint, 0x110> _temp_store;
+	return _temp_store.Get(i);
 }
 
 struct SpriteGroup;
@@ -243,7 +243,7 @@
 
 
 /* Base sprite group resolver */
-const SpriteGroup *Resolve(const SpriteGroup *group, ResolverObject *object, bool first_call = true);
+const SpriteGroup *Resolve(const SpriteGroup *group, ResolverObject *object);
 
 
 #endif /* NEWGRF_SPRITEGROUP_H */

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/newgrf_storage.cpp	Sat Sep 22 12:59:43 2007 +0000
@@ -0,0 +1,27 @@
+/* $Id$ */
+
+/** @file newgrf_storage.cpp Functionality related to the temporary and persistent storage arrays for NewGRFs. */
+
+#include "stdafx.h"
+#include "helpers.hpp"
+#include "newgrf_storage.h"
+#include <set>
+
+/** The changed storage arrays */
+static std::set<BaseStorageArray*> _changed_storage_arrays;
+
+void AddChangedStorage(BaseStorageArray *storage)
+{
+	_changed_storage_arrays.insert(storage);
+}
+
+void ClearStorageChanges(bool keep_changes)
+{
+	/* Loop over all changes arrays */
+	for (std::set<BaseStorageArray*>::iterator it = _changed_storage_arrays.begin(); it != _changed_storage_arrays.end(); it++) {
+		(*it)->ClearChanges(keep_changes);
+	}
+
+	/* And then clear that array */
+	_changed_storage_arrays.clear();
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/newgrf_storage.h	Sat Sep 22 12:59:43 2007 +0000
@@ -0,0 +1,176 @@
+/* $Id$ */
+
+/** @file newgrf_storage.h Functionality related to the temporary and persistent storage arrays for NewGRFs. */
+
+#ifndef NEWGRF_STORAGE_H
+#define NEWGRF_STORAGE_H
+
+/**
+ * Base class for all NewGRF storage arrays. Nothing fancy, only here
+ * so we have a generalised class to use.
+ */
+struct BaseStorageArray
+{
+	/** The needed destructor */
+	virtual ~BaseStorageArray() {}
+
+	/**
+	 * Clear the changes made since the last ClearChanges.
+	 * This can be done in two ways:
+	 *  - saving the changes permanently
+	 *  - reverting to the previous version
+	 * @param keep_changes do we save or revert the changes since the last ClearChanges?
+	 */
+	virtual void ClearChanges(bool keep_changes) {}
+};
+
+/**
+ * Class for persistent storage of data.
+ * On ClearChanges that data is either reverted or saved.
+ * @param TYPE the type of variable to store.
+ * @param SIZE the size of the array.
+ */
+template <typename TYPE, uint SIZE>
+struct PersistentStorageArray : BaseStorageArray {
+	TYPE storage[SIZE]; ///< Memory to for the storage array
+	TYPE *prev_storage; ///< Memory to store "old" states so we can revert them on the performance of test cases for commands etc.
+
+	/** Simply construct the array */
+	PersistentStorageArray() : prev_storage(NULL)
+	{
+		memset(this->storage, 0, sizeof(this->storage));
+	}
+
+	/** And free all data related to it */
+	~PersistentStorageArray()
+	{
+		free(this->prev_storage);
+	}
+
+	/**
+	 * Stores some value at a given position.
+	 * If there is no backup of the data that backup is made and then
+	 * we write the data.
+	 * @param pos   the position to write at
+	 * @param value the value to write
+	 */
+	void Store(uint pos, TYPE value)
+	{
+		/* Out of the scope of the array */
+		if (pos >= SIZE) return;
+
+		/* The value hasn't changed, so we pretend nothing happened.
+		 * Saves a few cycles and such and it's pretty easy to check. */
+		if (this->storage[pos] == value) return;
+
+		/* We do not have made a backup; lets do so */
+		if (this->prev_storage != NULL) {
+			this->prev_storage = MallocT<TYPE>(SIZE);
+			if (this->prev_storage == NULL) return;
+
+			memcpy(this->prev_storage, this->storage, sizeof(this->storage));
+
+			/* We only need to register ourselves when we made the backup
+			 * as that is the only time something will have changed */
+			AddChangedStorage(this);
+		}
+
+		this->storage[pos] = value;
+	}
+
+	/**
+	 * Gets the value from a given position.
+	 * @param pos the position to get the data from
+	 * @return the data from that position
+	 */
+	TYPE Get(uint pos)
+	{
+		/* Out of the scope of the array */
+		if (pos >= SIZE) return 0;
+
+		return this->storage[pos];
+	}
+
+	void ClearChanges(bool keep_changes)
+	{
+		assert(this->prev_storage != NULL);
+
+		if (!keep_changes) {
+			memcpy(this->storage, this->prev_storage, sizeof(this->storage));
+		}
+		free(this->prev_storage);
+	}
+};
+
+
+/**
+ * Class for temporary storage of data.
+ * On ClearChanges that data is always zero-ed.
+ * @param TYPE the type of variable to store.
+ * @param SIZE the size of the array.
+ */
+template <typename TYPE, uint SIZE>
+struct TemporaryStorageArray : BaseStorageArray {
+	TYPE storage[SIZE]; ///< Memory to for the storage array
+
+	/** Simply construct the array */
+	TemporaryStorageArray()
+	{
+		memset(this->storage, 0, sizeof(this->storage));
+	}
+
+	/**
+	 * Stores some value at a given position.
+	 * @param pos   the position to write at
+	 * @param value the value to write
+	 */
+	void Store(uint pos, TYPE value)
+	{
+		/* Out of the scope of the array */
+		if (pos >= SIZE) return;
+
+		this->storage[pos] = value;
+		AddChangedStorage(this);
+	}
+
+	/**
+	 * Gets the value from a given position.
+	 * @param pos the position to get the data from
+	 * @return the data from that position
+	 */
+	TYPE Get(uint pos)
+	{
+		/* Out of the scope of the array */
+		if (pos >= SIZE) return 0;
+
+		return this->storage[pos];
+	}
+
+	void ClearChanges(bool keep_changes)
+	{
+		memset(this->storage, 0, sizeof(this->storage));
+	}
+};
+
+/**
+ * Add the changed storage array to the list of changed arrays.
+ * This is done so we only have to revert/save the changed
+ * arrays, which saves quite a few clears, etc. after callbacks.
+ * @param storage the array that has changed
+ */
+void AddChangedStorage(BaseStorageArray *storage);
+
+
+/**
+ * Clear the changes made since the last ClearStorageChanges.
+ * This is done for *all* storages that have been registered to with
+ * AddChangedStorage since the previous ClearStorageChanges.
+ *
+ * This can be done in two ways:
+ *  - saving the changes permanently
+ *  - reverting to the previous version
+ * @param keep_changes do we save or revert the changes since the last ClearChanges?
+ */
+void ClearStorageChanges(bool keep_changes);
+
+#endif /* NEWGRF_STORAGE_H */

--- a/src/openttd.cpp	Sat Sep 22 00:59:27 2007 +0000
+++ b/src/openttd.cpp	Sat Sep 22 12:59:43 2007 +0000
@@ -61,6 +61,7 @@
 #include "newgrf_config.h"
 #include "newgrf_house.h"
 #include "newgrf_commons.h"
+#include "newgrf_storage.h"
 #include "player_face.h"
 #include "group.h"
 #include "blitter/factory.hpp"
@@ -977,6 +978,8 @@
  * That check is enforced in DoCommand. */
 void StateGameLoop()
 {
+	ClearStorageChanges(false);
+
 	/* dont execute the state loop during pause */
 	if (_pause_game) return;
 	if (IsGeneratingWorld()) return;