From 930d0c97021d9ec9d3acf37d916b236de0c1ca3a Mon Sep 17 00:00:00 2001
From: frosch <frosch@openttd.org>
Date: Sat, 14 May 2011 12:36:31 +0000
Subject: [PATCH] (svn r22452) -Fix (r18708): Zero register 0x100 as specified
 before resolving custom station foundations.

---
 src/newgrf_spritegroup.h | 11 +++++++++++
 src/newgrf_station.cpp   |  1 +
 2 files changed, 12 insertions(+)

diff --git a/src/newgrf_spritegroup.h b/src/newgrf_spritegroup.h
index da4d5e5df8..2541195d90 100644
--- a/src/newgrf_spritegroup.h
+++ b/src/newgrf_spritegroup.h
@@ -35,6 +35,17 @@ static inline uint32 GetRegister(uint i)
 	return _temp_store.Get(i);
 }
 
+/**
+ * Clears the value of a so-called newgrf "register".
+ * @param i index of the register
+ * @pre i < 0x110
+ */
+static inline void ClearRegister(uint i)
+{
+	extern TemporaryStorageArray<int32, 0x110> _temp_store;
+	_temp_store.Store(i, 0);
+}
+
 /* List of different sprite group types */
 enum SpriteGroupType {
 	SGT_REAL,
diff --git a/src/newgrf_station.cpp b/src/newgrf_station.cpp
index fd7a730ddf..4cc68e2a43 100644
--- a/src/newgrf_station.cpp
+++ b/src/newgrf_station.cpp
@@ -613,6 +613,7 @@ SpriteID GetCustomStationFoundationRelocation(const StationSpec *statspec, const
 	NewStationResolver(&object, statspec, st, tile);
 	object.callback_param1 = 2; // Indicate we are resolving the foundation sprites
 
+	ClearRegister(0x100);
 	group = ResolveStation(&object);
 	if (group == NULL || group->type != SGT_RESULT) return 0;
 	return group->GetResult() + GetRegister(0x100);