--- a/disaster_cmd.c	Mon Apr 10 14:27:26 2006 +0000
+++ b/disaster_cmd.c	Mon Apr 10 15:09:56 2006 +0000
@@ -339,7 +339,7 @@
 
 	for (tile = 0; tile != MapSize(); tile++) {
 		if (IsTileType(tile, MP_INDUSTRY) && GetIndustryIndex(tile) == i->index) {
-			_m[tile].m1 = 0;
+			ResetIndustryConstructionStage(tile);
 			MarkTileDirtyByTile(tile);
 		}
 	}

--- a/industry_cmd.c	Mon Apr 10 14:27:26 2006 +0000
+++ b/industry_cmd.c	Mon Apr 10 15:09:56 2006 +0000
@@ -356,7 +356,7 @@
 	ormod = GENERAL_SPRITE_COLOR(ind->color_map);
 
 	/* Retrieve pointer to the draw industry tile struct */
-	dits = &_industry_draw_tile_data[GetIndustryGfx(ti->tile) << 2 | GB(_m[ti->tile].m1, 0, 2)];
+	dits = &_industry_draw_tile_data[GetIndustryGfx(ti->tile) << 2 | GetIndustryConstructionStage(ti->tile)];
 
 	image = dits->sprite_1;
 	if (image & PALETTE_MODIFIER_COLOR && (image & PALETTE_SPRITE_MASK) == 0)
@@ -485,7 +485,8 @@
 			uint newgfx = _industry_produce_section[GetIndustryGfx(tile)];
 
 			if (newgfx != 0xFF) {
-				_m[tile].m1 = 0x80;
+				ResetIndustryConstructionStage(tile);
+				SetIndustryCompleted(tile, true);
 				SetIndustryGfx(tile, newgfx);
 				MarkTileDirtyByTile(tile);
 			}
@@ -678,18 +679,22 @@
 	CreateEffectVehicle(x + 15, y + 14, z + 59 + (tileh != 0 ? 8 : 0), EV_CHIMNEY_SMOKE);
 }
 
-static void MakeIndustryTileBigger(TileIndex tile, byte size)
+static void MakeIndustryTileBigger(TileIndex tile)
 {
-	byte b = (byte)((size + (1<<2)) & (3<<2));
+	byte cnt = GetIndustryConstructionCounter(tile) + 1;
+	byte stage;
 
-	if (b != 0) {
-		_m[tile].m1 = b | (size & 3);
+	if (cnt != 4) {
+		SetIndustryConstructionCounter(tile, cnt);
 		return;
 	}
 
-	size = (size + 1) & 3;
-	if (size == 3) size |= 0x80;
-	_m[tile].m1 = size | b;
+	stage = GetIndustryConstructionStage(tile) + 1;
+	SetIndustryConstructionCounter(tile, 0);
+	SetIndustryConstructionStage(tile, stage);
+	if (stage == 3) {
+		SetIndustryCompleted(tile, true);
+	}
 
 	MarkTileDirtyByTile(tile);
 
@@ -748,7 +753,7 @@
 	uint newgfx;
 
 	if (!IsIndustryCompleted(tile)) {
-		MakeIndustryTileBigger(tile, _m[tile].m1);
+		MakeIndustryTileBigger(tile);
 		return;
 	}
 
@@ -758,7 +763,7 @@
 
 	newgfx = _industry_section_animation_next[GetIndustryGfx(tile)];
 	if (newgfx != 255) {
-		_m[tile].m1 = 0;
+		ResetIndustryConstructionStage(tile);
 		SetIndustryGfx(tile, newgfx);
 		MarkTileDirtyByTile(tile);
 		return;

--- a/industry_map.h	Mon Apr 10 14:27:26 2006 +0000
+++ b/industry_map.h	Mon Apr 10 15:09:56 2006 +0000
@@ -1,5 +1,10 @@
 /* $Id$ */
 
+/** @file industry_map.h Accessors for industries */
+
+#ifndef INDUSTRY_MAP_H
+#define INDUSTRY_MAP_H
+
 #include "industry.h"
 #include "macros.h"
 #include "tile.h"
@@ -16,13 +21,47 @@
 	return GetIndustry(GetIndustryIndex(t));
 }
 
-
 static inline bool IsIndustryCompleted(TileIndex t)
 {
 	assert(IsTileType(t, MP_INDUSTRY));
 	return HASBIT(_m[t].m1, 7);
 }
 
+/**
+ * Set if the industry that owns the tile as under construction or not
+ * @param tile the tile to query
+ * @param isCompleted whether it is completed or not
+ * @pre IsTileType(tile, MP_INDUSTRY)
+ */
+static inline void SetIndustryCompleted(TileIndex tile, bool isCompleted)
+{
+	assert(IsTileType(tile, MP_INDUSTRY));
+	SB(_m[tile].m1, 7, 1, isCompleted ? 1 :0);
+}
+
+/**
+ * Returns the industry construction stage of the specified tile
+ * @param tile the tile to query
+ * @pre IsTileType(tile, MP_INDUSTRY)
+ * @return the construction stage
+ */
+static inline byte GetIndustryConstructionStage(TileIndex tile)
+{
+	assert(IsTileType(tile, MP_INDUSTRY));
+	return GB(_m[tile].m1, 0, 2);
+}
+
+/**
+ * Sets the industry construction stage of the specified tile
+ * @param tile the tile to query
+ * @param value the new construction stage
+ * @pre IsTileType(tile, MP_INDUSTRY)
+ */
+static inline void SetIndustryConstructionStage(TileIndex tile, byte value)
+{
+	assert(IsTileType(tile, MP_INDUSTRY));
+	SB(_m[tile].m1, 0, 2, value);
+}
 
 static inline uint GetIndustryGfx(TileIndex t)
 {
@@ -36,7 +75,6 @@
 	_m[t].m5 = gfx;
 }
 
-
 static inline void MakeIndustry(TileIndex t, uint index, uint gfx)
 {
 	SetTileType(t, MP_INDUSTRY);
@@ -46,3 +84,43 @@
 	_m[t].m4 = 0;
 	_m[t].m5 = gfx;
 }
+
+/**
+ * Returns this indutry tile's construction counter value
+ * @param tile the tile to query
+ * @pre IsTileType(tile, MP_INDUSTRY)
+ * @return the construction counter
+ */
+static inline byte GetIndustryConstructionCounter(TileIndex tile)
+{
+	assert(IsTileType(tile, MP_INDUSTRY));
+	return GB(_m[tile].m1, 2, 2);
+}
+
+/**
+ * Sets this indutry tile's construction counter value
+ * @param tile the tile to query
+ * @param value the new value for the construction counter
+ * @pre IsTileType(tile, MP_INDUSTRY)
+ */
+static inline void SetIndustryConstructionCounter(TileIndex tile, byte value)
+{
+	assert(IsTileType(tile, MP_INDUSTRY));
+	SB(_m[tile].m1, 2, 2, value);
+}
+
+/**
+ * Reset the construction stage counter of the industry,
+ * as well as the completion bit.
+ * In fact, it is the same as restarting construction frmo ground up
+ * @param tile the tile to query
+ * @param generating_world whether generating a world or not
+ * @pre IsTileType(tile, MP_INDUSTRY)
+ */
+static inline void ResetIndustryConstructionStage(TileIndex tile)
+{
+	assert(IsTileType(tile, MP_INDUSTRY));
+	_m[tile].m1 = 0;
+}
+
+#endif /* INDUSTRY_MAP_H */