--- a/ai.c	Mon Feb 07 10:37:12 2005 +0000
+++ b/ai.c	Mon Feb 07 10:41:45 2005 +0000
@@ -1708,7 +1708,7 @@
 	byte old_player;
 	uint32 r;
 	uint slope;
-	int h;
+	uint h;
 
 	old_player = _current_player;
 	_current_player = OWNER_NONE;

--- a/functions.h	Mon Feb 07 10:37:12 2005 +0000
+++ b/functions.h	Mon Feb 07 10:41:45 2005 +0000
@@ -9,8 +9,6 @@
 /* landscape.c */
 void FindLandscapeHeight(TileInfo *ti, uint x, uint y);
 void FindLandscapeHeightByTile(TileInfo *ti, uint tile);
-uint GetTileSlope(uint tile, int *h);
-int GetTileZ(uint tile);
 
 void DoClearSquare(uint tile);
 void CDECL ModifyTile(uint tile, uint flags, ...);

--- a/industry_cmd.c	Mon Feb 07 10:37:12 2005 +0000
+++ b/industry_cmd.c	Mon Feb 07 10:41:45 2005 +0000
@@ -959,7 +959,7 @@
 	int type, type2;
 
 	if (_opt.landscape == LT_HILLY) {
-		if (GetTileZ(tile) >= (_opt.snow_line - 16))
+		if (GetTileZ(tile) + 16 >= _opt.snow_line)
 			return;
 	}
 
@@ -1169,7 +1169,7 @@
 static bool CheckNewIndustry_Forest(uint tile, int type)
 {
 	if (_opt.landscape == LT_HILLY) {
-		if (GetTileZ(tile) < (_opt.snow_line + 16) ) {
+		if (GetTileZ(tile) < _opt.snow_line + 16U) {
 			_error_message = STR_4831_FOREST_CAN_ONLY_BE_PLANTED;
 			return false;
 		}
@@ -1202,7 +1202,7 @@
 static bool CheckNewIndustry_Farm(uint tile, int type)
 {
 	if (_opt.landscape == LT_HILLY) {
-		if (GetTileZ(tile) >= (_opt.snow_line - 16)) {
+		if (GetTileZ(tile) + 16 >= _opt.snow_line) {
 			_error_message = STR_0239_SITE_UNSUITABLE;
 			return false;
 		}

--- a/landscape.c	Mon Feb 07 10:37:12 2005 +0000
+++ b/landscape.c	Mon Feb 07 10:41:45 2005 +0000
@@ -41,45 +41,6 @@
 	0,0,0,0,0,0,0,16,0,0,0,17,0,15,18,0,
 };
 
-uint GetTileSlope(uint tile, int *h)
-{
-	uint a,b,c,d,min;
-	int r;
-
-	assert(tile < MapSize());
-
-	if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) {
-		if (h)
-			*h = 0;
-		return 0;
-	}
-
-	min = a = TileHeight(tile);
-	b = TileHeight(tile + TILE_XY(1,0));
-	if (min >= b) min = b;
-	c = TileHeight(tile + TILE_XY(0,1));
-	if (min >= c) min = c;
-	d = TileHeight(tile + TILE_XY(1,1));
-	if (min >= d) min = d;
-
-	r = 0;
-	if ((a-=min)!=0) { r += (--a << 4) + 8; }
-	if ((c-=min)!=0) { r += (--c << 4) + 4; }
-	if ((d-=min)!=0) { r += (--d << 4) + 2; }
-	if ((b-=min)!=0) { r += (--b << 4) + 1; }
-
-	if (h != 0)
-		*h = min * 8;
-
-	return r;
-}
-
-int GetTileZ(uint tile)
-{
-	int h;
-	GetTileSlope(tile, &h);
-	return h;
-}
 
 void FindLandscapeHeightByTile(TileInfo *ti, TileIndex tile)
 {
@@ -488,7 +449,7 @@
 void ConvertGroundTilesIntoWaterTiles(void)
 {
 	TileIndex tile = 0;
-	int h;
+	uint h;
 
 	for (tile = 0; tile < MapSize(); ++tile) {
 		if (IsTileType(tile, MP_CLEAR) && GetTileSlope(tile, &h) == 0 && h == 0) {

--- a/station_cmd.c	Mon Feb 07 10:37:12 2005 +0000
+++ b/station_cmd.c	Mon Feb 07 10:41:45 2005 +0000
@@ -757,7 +757,9 @@
 	int32 cost = 0, ret;
 
 	uint tileh;
-	int z, allowed_z = -1, flat_z;
+	uint z;
+	int allowed_z = -1;
+	int flat_z;
 
 	BEGIN_TILE_LOOP(tile_cur, w, h, tile)
 		if (!EnsureNoVehicle(tile_cur))

--- a/tile.c	Mon Feb 07 10:37:12 2005 +0000
+++ b/tile.c	Mon Feb 07 10:41:45 2005 +0000
@@ -13,3 +13,47 @@
 	assert(tile < MapSize());
 	return (_map_extra_bits[tile >> 2] >> (tile & 3) * 2) & 3;
 }
+
+
+uint GetTileSlope(TileIndex tile, uint *h)
+{
+	uint a;
+	uint b;
+	uint c;
+	uint d;
+	uint min;
+	uint r;
+
+	assert(tile < MapSize());
+
+	if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) {
+		if (h != NULL) *h = 0;
+		return 0;
+	}
+
+	min = a = TileHeight(tile);
+	b = TileHeight(tile + TILE_XY(1,0));
+	if (min >= b) min = b;
+	c = TileHeight(tile + TILE_XY(0,1));
+	if (min >= c) min = c;
+	d = TileHeight(tile + TILE_XY(1,1));
+	if (min >= d) min = d;
+
+	r = 0;
+	if ((a -= min) != 0) { r += (--a << 4) + 8; }
+	if ((c -= min) != 0) { r += (--c << 4) + 4; }
+	if ((d -= min) != 0) { r += (--d << 4) + 2; }
+	if ((b -= min) != 0) { r += (--b << 4) + 1; }
+
+	if (h != NULL)
+		*h = min * 8;
+
+	return r;
+}
+
+uint GetTileZ(TileIndex tile)
+{
+	uint h;
+	GetTileSlope(tile, &h);
+	return h;
+}

--- a/tile.h	Mon Feb 07 10:37:12 2005 +0000
+++ b/tile.h	Mon Feb 07 10:41:45 2005 +0000
@@ -20,6 +20,9 @@
 void SetMapExtraBits(TileIndex tile, byte flags);
 uint GetMapExtraBits(TileIndex tile);
 
+uint GetTileSlope(TileIndex tile, uint *h);
+uint GetTileZ(TileIndex tile);
+
 static inline uint TileHeight(TileIndex tile)
 {
 	assert(tile < MapSize());

--- a/town_cmd.c	Mon Feb 07 10:37:12 2005 +0000
+++ b/town_cmd.c	Mon Feb 07 10:41:45 2005 +0000
@@ -1144,7 +1144,7 @@
 	uint bitmask;
 	int house;
 	uint slope;
-	int z;
+	uint z;
 	uint oneof;
 
 	// Above snow?

--- a/tunnelbridge_cmd.c	Mon Feb 07 10:37:12 2005 +0000
+++ b/tunnelbridge_cmd.c	Mon Feb 07 10:41:45 2005 +0000
@@ -586,7 +586,7 @@
 
 uint CheckTunnelBusy(uint tile, int *length)
 {
-	int z = GetTileZ(tile);
+	uint z = GetTileZ(tile);
 	byte m5 = _map5[tile];
 	int delta = TileOffsByDir(m5 & 3);
 	int len = 0;
@@ -1404,7 +1404,6 @@
 	int z;
 	int dir, vdir;
 	byte fc;
-	int h;
 
 	if ((_map5[tile] & 0xF0) == 0) {
 		z = GetSlopeZ(x, y) - v->z_pos;
@@ -1472,6 +1471,8 @@
 		}
 	} else if (_map5[tile] & 0x80) {
 		if (v->type == VEH_Road || (v->type == VEH_Train && v->subtype == TS_Front_Engine)) {
+			uint h;
+
 			if (GetTileSlope(tile, &h) != 0)
 				h += 8; // Compensate for possible foundation
 			if (!(_map5[tile] & 0x40) || // start/end tile of bridge

--- a/unmovable_cmd.c	Mon Feb 07 10:37:12 2005 +0000
+++ b/unmovable_cmd.c	Mon Feb 07 10:41:45 2005 +0000
@@ -253,7 +253,7 @@
 	uint tile;
 	uint32 r;
 	int dir;
-	int h;
+	uint h;
 
 	if (_opt.landscape == LT_CANDY)
 		return;