(svn r8698) -Codechange: enumify the returns of VehicleEnterTile

11 files changed, 67 insertions, 51 deletions

diff --git a/src/openttd.h b/src/openttd.h
index 0126d72c8..b4581ea36 100644
--- a/src/openttd.h
+++ b/src/openttd.h
@@ -361,10 +361,7 @@ typedef void ClickTileProc(TileIndex tile);
 typedef void AnimateTileProc(TileIndex tile);
 typedef void TileLoopProc(TileIndex tile);
 typedef void ChangeTileOwnerProc(TileIndex tile, PlayerID old_player, PlayerID new_player);
-/* Return value has bit 0x2 set, when the vehicle enters a station. Then,
- * result << 8 contains the id of the station entered. If the return value has
- * bit 0x8 set, the vehicle could not and did not enter the tile. Are there
- * other bits that can be set? */
+/** @see VehicleEnterTileStatus to see what the return values mean */
 typedef uint32 VehicleEnterTileProc(Vehicle *v, TileIndex tile, int x, int y);
 typedef Slope GetSlopeTilehProc(TileIndex, Slope tileh);
 
diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index 04deae559..bb8ba81a8 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -1946,7 +1946,7 @@ static uint32 VehicleEnter_Track(Vehicle *v, TileIndex tile, int x, int y)
 	int length;
 
 	// this routine applies only to trains in depot tiles
-	if (v->type != VEH_Train || !IsTileDepotType(tile, TRANSPORT_RAIL)) return 0;
+	if (v->type != VEH_Train || !IsTileDepotType(tile, TRANSPORT_RAIL)) return VETSB_CONTINUE;
 
 	/* depot direction */
 	dir = GetRailDepotDirection(tile);
@@ -1965,7 +1965,7 @@ static uint32 VehicleEnter_Track(Vehicle *v, TileIndex tile, int x, int y)
 
 	if (_fractcoords_behind[dir] == fract_coord) {
 		/* make sure a train is not entering the tile from behind */
-		return 8;
+		return VETSB_CANNOT_ENTER;
 	} else if (_fractcoords_enter[dir] == fract_coord) {
 		if (DiagDirToDir(ReverseDiagDir(dir)) == v->direction) {
 			/* enter the depot */
@@ -1976,7 +1976,7 @@ static uint32 VehicleEnter_Track(Vehicle *v, TileIndex tile, int x, int y)
 			v->tile = tile;
 
 			InvalidateWindowData(WC_VEHICLE_DEPOT, v->tile);
-			return 4;
+			return VETSB_ENTERED_WORMHOLE;
 		}
 	} else if (fract_coord_leave == fract_coord) {
 		if (DiagDirToDir(dir) == v->direction) {
@@ -1988,7 +1988,7 @@ static uint32 VehicleEnter_Track(Vehicle *v, TileIndex tile, int x, int y)
 		}
 	}
 
-	return 0;
+	return VETSB_CONTINUE;
 }
 
 
diff --git a/src/road_cmd.cpp b/src/road_cmd.cpp
index cbad915d4..caea8ea2d 100644
--- a/src/road_cmd.cpp
+++ b/src/road_cmd.cpp
@@ -1016,13 +1016,13 @@ static uint32 VehicleEnter_Road(Vehicle *v, TileIndex tile, int x, int y)
 					v->u.road.frame == 11 &&
 					_roadveh_enter_depot_unk0[GetRoadDepotDirection(tile)] == v->u.road.state) {
 				VehicleEnterDepot(v);
-				return 4;
+				return VETSB_ENTERED_WORMHOLE;
 			}
 			break;
 
 		default: break;
 	}
-	return 0;
+	return VETSB_CONTINUE;
 }
 
 
diff --git a/src/roadveh_cmd.cpp b/src/roadveh_cmd.cpp
index 3c1278985..34035e621 100644
--- a/src/roadveh_cmd.cpp
+++ b/src/roadveh_cmd.cpp
@@ -1340,7 +1340,7 @@ static void RoadVehController(Vehicle *v)
 			return;
 		}
 
-		if ((IsTunnelTile(gp.new_tile) || IsBridgeTile(gp.new_tile)) && VehicleEnterTile(v, gp.new_tile, gp.x, gp.y) & 4) {
+		if ((IsTunnelTile(gp.new_tile) || IsBridgeTile(gp.new_tile)) && HASBIT(VehicleEnterTile(v, gp.new_tile, gp.x, gp.y), VETS_ENTERED_WORMHOLE)) {
 			/* Vehicle has just entered a bridge or tunnel */
 			v->cur_image = GetRoadVehImage(v, v->direction);
 			UpdateRoadVehDeltaXY(v);
@@ -1388,7 +1388,7 @@ again:
 		if (RoadVehFindCloseTo(v, x, y, newdir) != NULL) return;
 
 		r = VehicleEnterTile(v, tile, x, y);
-		if (r & 8) {
+		if (HASBIT(r, VETS_CANNOT_ENTER)) {
 			/* Vehicle cannot enter the tile */
 			if (!IsTileType(tile, MP_TUNNELBRIDGE)) {
 				v->cur_speed = 0;
@@ -1416,7 +1416,7 @@ again:
 			}
 		}
 
-		if (!(r & 4)) {
+		if (!HASBIT(r, VETS_ENTERED_WORMHOLE)) {
 			/* Set vehicle to first frame on new tile */
 			v->tile = tile;
 			v->u.road.state = (byte)dir;
@@ -1457,7 +1457,7 @@ again:
 		if (RoadVehFindCloseTo(v, x, y, newdir) != NULL) return;
 
 		r = VehicleEnterTile(v, v->tile, x, y);
-		if (r & 8) {
+		if (HASBIT(r, VETS_CANNOT_ENTER)) {
 			/* Vehicle cannot enter the tile */
 			v->cur_speed = 0;
 			return;
@@ -1599,7 +1599,7 @@ again:
 	/* Check tile position conditions - i.e. stop position in depot,
 	 * entry onto bridge or into tunnel */
 	r = VehicleEnterTile(v, v->tile, x, y);
-	if (r & 8) {
+	if (HASBIT(r, VETS_CANNOT_ENTER)) {
 		/* Vehicle cannot continue */
 		v->cur_speed = 0;
 		return;
@@ -1607,7 +1607,7 @@ again:
 
 	/* Move to next frame unless vehicle arrived at a stop position
 	 * in a depot or entered a tunnel/bridge */
-	if ((r & 4) == 0) v->u.road.frame++;
+	if (!HASBIT(r, VETS_ENTERED_WORMHOLE)) v->u.road.frame++;
 
 	v->cur_image = GetRoadVehImage(v, v->direction);
 	UpdateRoadVehDeltaXY(v);
diff --git a/src/ship_cmd.cpp b/src/ship_cmd.cpp
index 82408ad23..6b73dade8 100644
--- a/src/ship_cmd.cpp
+++ b/src/ship_cmd.cpp
@@ -700,7 +700,7 @@ static void ShipController(Vehicle *v)
 		} else {
 			/* isnot inside depot */
 			r = VehicleEnterTile(v, gp.new_tile, gp.x, gp.y);
-			if (r & 0x8) goto reverse_direction;
+			if (HASBIT(r, VETS_CANNOT_ENTER)) goto reverse_direction;
 
 			/* A leave station order only needs one tick to get processed, so we can
 			 * always skip ahead. */
@@ -780,9 +780,9 @@ static void ShipController(Vehicle *v)
 
 		/* Call the landscape function and tell it that the vehicle entered the tile */
 		r = VehicleEnterTile(v, gp.new_tile, gp.x, gp.y);
-		if (r&0x8) goto reverse_direction;
+		if (HASBIT(r, VETS_CANNOT_ENTER)) goto reverse_direction;
 
-		if (!(r&0x4)) {
+		if (!HASBIT(r, VETS_ENTERED_WORMHOLE)) {
 			v->tile = gp.new_tile;
 			v->u.ship.state = TrackToTrackBits(track);
 		}
diff --git a/src/station_cmd.cpp b/src/station_cmd.cpp
index 2e3ae49c6..d994aa7ee 100644
--- a/src/station_cmd.cpp
+++ b/src/station_cmd.cpp
@@ -2260,7 +2260,7 @@ static uint32 VehicleEnter_Station(Vehicle *v, TileIndex tile, int x, int y)
 					if (DiagDirToAxis(dir) != AXIS_X) intswap(x, y);
 					if (y == TILE_SIZE / 2) {
 						if (dir != DIAGDIR_SE && dir != DIAGDIR_SW) x = TILE_SIZE - 1 - x;
-						if (x == 12) return 2 | (station_id << 8); /* enter station */
+						if (x == 12) return VETSB_ENTERED_STATION | (station_id << VETS_STATION_ID_OFFSET); /* enter station */
 						if (x < 12) {
 							uint16 spd;
 
@@ -2279,7 +2279,7 @@ static uint32 VehicleEnter_Station(Vehicle *v, TileIndex tile, int x, int y)
 				RoadStop *rs = GetRoadStopByTile(tile, GetRoadStopType(tile));
 
 				/* Check if station is busy or if there are no free bays. */
-				if (rs->IsEntranceBusy() || !rs->HasFreeBay()) return 8;
+				if (rs->IsEntranceBusy() || !rs->HasFreeBay()) return VETSB_CANNOT_ENTER;
 
 				v->u.road.state += 32;
 
@@ -2293,7 +2293,7 @@ static uint32 VehicleEnter_Station(Vehicle *v, TileIndex tile, int x, int y)
 		}
 	}
 
-	return 0;
+	return VETSB_CONTINUE;
 }
 
 /* this function is called for one station each tick */
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index 37e42cde0..3020caa8e 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -3022,12 +3022,11 @@ static void TrainController(Vehicle *v, bool update_image)
 					if (IsFrontEngine(v) && !TrainCheckIfLineEnds(v)) return;
 
 					r = VehicleEnterTile(v, gp.new_tile, gp.x, gp.y);
-					if (r & 0x8) {
-						//debug("%x & 0x8", r);
+					if (HASBIT(r, VETS_ENTERED_WORMHOLE)) {
 						goto invalid_rail;
 					}
-					if (r & 0x2) {
-						TrainEnterStation(v, r >> 8);
+					if (HASBIT(r, VETS_ENTERED_STATION)) {
+						TrainEnterStation(v, r >> VETS_STATION_ID_OFFSET);
 						return;
 					}
 
@@ -3101,8 +3100,7 @@ static void TrainController(Vehicle *v, bool update_image)
 
 				/* Call the landscape function and tell it that the vehicle entered the tile */
 				r = VehicleEnterTile(v, gp.new_tile, gp.x, gp.y);
-				if (r & 0x8) {
-					//debug("%x & 0x8", r);
+				if (HASBIT(r, VETS_CANNOT_ENTER)) {
 					goto invalid_rail;
 				}
 
@@ -3113,7 +3111,7 @@ static void TrainController(Vehicle *v, bool update_image)
 
 				if (IsFrontEngine(v)) v->load_unload_time_rem = 0;
 
-				if (!(r&0x4)) {
+				if (!HASBIT(r, VETS_ENTERED_WORMHOLE)) {
 					v->tile = gp.new_tile;
 
 					if (GetTileRailType(gp.new_tile, FindFirstTrack(chosen_track)) != GetTileRailType(gp.old_tile, FindFirstTrack(v->u.rail.track))) {
@@ -3141,7 +3139,7 @@ static void TrainController(Vehicle *v, bool update_image)
 
 			SetSpeedLimitOnBridge(v);
 
-			if (!(IsTunnelTile(gp.new_tile) || IsBridgeTile(gp.new_tile)) || !(VehicleEnterTile(v, gp.new_tile, gp.x, gp.y) & 0x4)) {
+			if (!(IsTunnelTile(gp.new_tile) || IsBridgeTile(gp.new_tile)) || !HASBIT(VehicleEnterTile(v, gp.new_tile, gp.x, gp.y), VETS_ENTERED_WORMHOLE)) {
 				v->x_pos = gp.x;
 				v->y_pos = gp.y;
 				VehiclePositionChanged(v);
diff --git a/src/tunnelbridge_cmd.cpp b/src/tunnelbridge_cmd.cpp
index eab5b2a18..3df78215c 100644
--- a/src/tunnelbridge_cmd.cpp
+++ b/src/tunnelbridge_cmd.cpp
@@ -1262,7 +1262,7 @@ static uint32 VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y
 {
 	int z = GetSlopeZ(x, y) - v->z_pos;
 
-	if (myabs(z) > 2) return 8;
+	if (myabs(z) > 2) return VETSB_CANNOT_ENTER;
 
 	if (IsTunnel(tile)) {
 		byte fc;
@@ -1280,13 +1280,13 @@ static uint32 VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y
 					if (!PlayVehicleSound(v, VSE_TUNNEL) && v->spritenum < 4) {
 						SndPlayVehicleFx(SND_05_TRAIN_THROUGH_TUNNEL, v);
 					}
-					return 0;
+					return VETSB_CONTINUE;
 				}
 				if (fc == _tunnel_fractcoord_2[dir]) {
 					v->tile = tile;
 					v->u.rail.track = TRACK_BIT_WORMHOLE;
 					v->vehstatus |= VS_HIDDEN;
-					return 4;
+					return VETSB_ENTERED_WORMHOLE;
 				}
 			}
 
@@ -1296,7 +1296,7 @@ static uint32 VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y
 				v->u.rail.track = (TrackBits)_exit_tunnel_track[dir];
 				assert(v->u.rail.track);
 				v->vehstatus &= ~VS_HIDDEN;
-				return 4;
+				return VETSB_ENTERED_WORMHOLE;
 			}
 		} else if (v->type == VEH_Road) {
 			fc = (x & 0xF) + (y << 4);
@@ -1310,9 +1310,9 @@ static uint32 VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y
 					v->tile = tile;
 					v->u.road.state = 0xFF;
 					v->vehstatus |= VS_HIDDEN;
-					return 4;
+					return VETSB_ENTERED_WORMHOLE;
 				} else {
-					return 0;
+					return VETSB_CONTINUE;
 				}
 			}
 
@@ -1326,7 +1326,7 @@ static uint32 VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y
 				v->u.road.state = _road_exit_tunnel_state[dir];
 				v->u.road.frame = _road_exit_tunnel_frame[dir];
 				v->vehstatus &= ~VS_HIDDEN;
-				return 4;
+				return VETSB_ENTERED_WORMHOLE;
 			}
 		}
 	} else if (IsBridge(tile)) { // XXX is this necessary?
@@ -1344,10 +1344,10 @@ static uint32 VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y
 		if (DirToDiagDir(v->direction) == dir) {
 			switch (dir) {
 				default: NOT_REACHED();
-				case DIAGDIR_NE: if ((x & 0xF) != 0)             return 0; break;
-				case DIAGDIR_SE: if ((y & 0xF) != TILE_SIZE - 1) return 0; break;
-				case DIAGDIR_SW: if ((x & 0xF) != TILE_SIZE - 1) return 0; break;
-				case DIAGDIR_NW: if ((y & 0xF) != 0)             return 0; break;
+				case DIAGDIR_NE: if ((x & 0xF) != 0)             return VETSB_CONTINUE; break;
+				case DIAGDIR_SE: if ((y & 0xF) != TILE_SIZE - 1) return VETSB_CONTINUE; break;
+				case DIAGDIR_SW: if ((x & 0xF) != TILE_SIZE - 1) return VETSB_CONTINUE; break;
+				case DIAGDIR_NW: if ((y & 0xF) != 0)             return VETSB_CONTINUE; break;
 			}
 			if (v->type == VEH_Train) {
 				v->u.rail.track = TRACK_BIT_WORMHOLE;
@@ -1356,25 +1356,25 @@ static uint32 VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y
 			} else {
 				v->u.road.state = 0xFF;
 			}
-			return 4;
+			return VETSB_ENTERED_WORMHOLE;
 		} else if (DirToDiagDir(v->direction) == ReverseDiagDir(dir)) {
 			v->tile = tile;
 			if (v->type == VEH_Train) {
 				if (v->u.rail.track == 0x40) {
 					v->u.rail.track = (DiagDirToAxis(dir) == AXIS_X ? TRACK_BIT_X : TRACK_BIT_Y);
-					return 4;
+					return VETSB_ENTERED_WORMHOLE;
 				}
 			} else {
 				if (v->u.road.state == 0xFF) {
 					v->u.road.state = _road_exit_tunnel_state[dir];
 					v->u.road.frame = 0;
-					return 4;
+					return VETSB_ENTERED_WORMHOLE;
 				}
 			}
-			return 0;
+			return VETSB_CONTINUE;
 		}
 	}
-	return 0;
+	return VETSB_CONTINUE;
 }
 
 extern const TileTypeProcs _tile_type_tunnelbridge_procs = {
diff --git a/src/vehicle.cpp b/src/vehicle.cpp
index bdee6fcd5..5f6fe6a52 100644
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -2769,10 +2769,11 @@ Trackdir GetVehicleTrackdir(const Vehicle* v)
 		default: return INVALID_TRACKDIR;
 	}
 }
-/* Return value has bit 0x2 set, when the vehicle enters a station. Then,
- * result << 8 contains the id of the station entered. If the return value has
- * bit 0x8 set, the vehicle could not and did not enter the tile. Are there
- * other bits that can be set? */
+
+/**
+ * Returns some meta-data over the to be entered tile.
+ * @see VehicleEnterTileStatus to see what the bits in the return value mean.
+ */
 uint32 VehicleEnterTile(Vehicle *v, TileIndex tile, int x, int y)
 {
 	return _tile_type_procs[GetTileType(tile)]->vehicle_enter_tile_proc(v, tile, x, y);
diff --git a/src/vehicle.h b/src/vehicle.h
index 9fa8837d9..7a2fe8780 100644
--- a/src/vehicle.h
+++ b/src/vehicle.h
@@ -7,6 +7,26 @@
 #include "order.h"
 #include "rail.h"
 
+/** The returned bits of VehicleEnterTile. */
+enum VehicleEnterTileStatus {
+	VETS_ENTERED_STATION  = 1, ///< The vehicle entered a station
+	VETS_ENTERED_WORMHOLE = 2, ///< The vehicle either entered a bridge, tunnel or depot tile (this includes the last tile of the bridge/tunnel)
+	VETS_CANNOT_ENTER     = 3, ///< The vehicle cannot enter the tile
+
+	/**
+	 * Shift the VehicleEnterTileStatus this many bits
+	 * to the right to get the station ID when
+	 * VETS_ENTERED_STATION is set
+	 */
+	VETS_STATION_ID_OFFSET = 8,
+
+	/** Bit sets of the above specified bits */
+	VETSB_CONTINUE         = 0,                          ///< The vehicle can continue normally
+	VETSB_ENTERED_STATION  = 1 << VETS_ENTERED_STATION,  ///< The vehicle entered a station
+	VETSB_ENTERED_WORMHOLE = 1 << VETS_ENTERED_WORMHOLE, ///< The vehicle either entered a bridge, tunnel or depot tile (this includes the last tile of the bridge/tunnel)
+	VETSB_CANNOT_ENTER     = 1 << VETS_CANNOT_ENTER,     ///< The vehicle cannot enter the tile
+};
+
 enum {
 	VEH_Train,
 	VEH_Road,
diff --git a/src/water_cmd.cpp b/src/water_cmd.cpp
index 00f2fa934..cd42138d5 100644
--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -742,7 +742,7 @@ static void ChangeTileOwner_Water(TileIndex tile, PlayerID old_player, PlayerID
 
 static uint32 VehicleEnter_Water(Vehicle *v, TileIndex tile, int x, int y)
 {
-	return 0;
+	return VETSB_CONTINUE;
 }