(svn r8694) -Codechange: make RoadStop's status accessible via accessor functions.

src/roadveh_cmd.cpp

@@ -490,11 +490,11 @@ static void ClearCrashedStation(Vehicle *v)
 {
 	RoadStop *rs = GetRoadStopByTile(v->tile, GetRoadStopType(v->tile));
 
-	// mark station as not busy
+	/* Mark the station entrance as not busy */
-	CLRBIT(rs->status, 7);
+	rs->SetEntranceBusy(false);
 
-	// free parking bay
+	/* Free the parking bay */
-	SETBIT(rs->status, HASBIT(v->u.road.state, 1) ? 1 : 0);
+	rs->FreeBay(HASBIT(v->u.road.state, 1) ? 1 : 0);
 }
 
 static void RoadVehDelete(Vehicle *v)
@@ -1080,7 +1080,7 @@ static int RoadFindPathToDest(Vehicle* v, TileIndex tile, DiagDirection enterdir
 			} else {
 				// proper station type, check if there is free loading bay
 				if (!_patches.roadveh_queue &&
-						GB(GetRoadStopByTile(tile, rstype)->status, 0, 2) == 0) {
+						!GetRoadStopByTile(tile, rstype)->HasFreeBay()) {
 					// station is full and RV queuing is off
 					bitmask = 0;
 				}
@@ -1411,8 +1411,8 @@ again:
 				RoadStop *rs = GetRoadStopByTile(v->tile, GetRoadStopType(v->tile));
 
 				/* Vehicle is leaving a road stop tile, mark bay as free and clear the usage bit */
-				SETBIT(rs->status, v->u.road.state & 2 ? 1 : 0); // set bay as free
+				rs->FreeBay(HASBIT(v->u.road.state, 1) ? 1 : 0);
-				CLRBIT(rs->status, 7); // usage bit
+				rs->SetEntranceBusy(false);
 			}
 		}
 
@@ -1527,7 +1527,7 @@ again:
 			Order old_order;
 
 			/* Clear road stop busy bit to allow another vehicle to enter or leave */
-			CLRBIT(rs->status, 7);
+			rs->SetEntranceBusy(false);
 
 			v->last_station_visited = GetStationIndex(v->tile);
 
@@ -1554,8 +1554,8 @@ again:
 
 		/* Vehicle is ready to leave a bay in a road stop */
 		if (v->current_order.type != OT_GOTO_DEPOT) {
-			if (HASBIT(rs->status, 7)) {
+			if (rs->IsEntranceBusy()) {
-				/* Road stop is busy, so wait */
+				/* Road stop entrance is busy, so wait */
 				v->cur_speed = 0;
 				return;
 			}
@@ -1564,7 +1564,7 @@ again:
 			ClearSlot(v);
 		}
 		/* Set road stop busy bit to prevent another vehicle trying to enter or leave */
-		SETBIT(rs->status, 7);
+		rs->SetEntranceBusy(true);
 
 		if (rs == v->u.road.slot) {
 			/* We are leaving the correct station */

src/station.cpp

@@ -437,3 +437,52 @@ bool RoadStop::IsValid() const
 {
 	return xy != INVALID_TILE;
 }
+
+/** Checks whether there is a free bay in this road stop */
+bool RoadStop::HasFreeBay() const
+{
+	return GB(status, 0, MAX_BAY_COUNT) != 0;
+}
+
+/**
+ * Allocates a bay
+ * @return the allocated bay number
+ * @pre this->HasFreeBay()
+ */
+uint RoadStop::AllocateBay()
+{
+	/* Find the first free bay. If the bit is set, the bay is free. */
+	for (uint bay_nr = 0; bay_nr < MAX_BAY_COUNT; bay_nr++) {
+		if (HASBIT(status, bay_nr)) {
+			CLRBIT(status, bay_nr);
+			return bay_nr;
+		}
+	}
+
+	/* There has to be a free bay (precondition) */
+	NOT_REACHED();
+	return 0;
+}
+
+/**
+ * Frees the given bay
+ * @param nr the number of the bay to free
+ */
+void RoadStop::FreeBay(uint nr)
+{
+	assert(nr < MAX_BAY_COUNT);
+	SETBIT(status, nr);
+}
+
+
+/** Checks whether the entrance of the road stop is occupied by a vehicle */
+bool RoadStop::IsEntranceBusy() const
+{
+	return HASBIT(status, 7);
+}
+
+/** Makes an entrance occupied or free */
+void RoadStop::SetEntranceBusy(bool busy)
+{
+	SB(status, 7, 1, !!busy);
+}

src/station.h

@@ -44,10 +44,11 @@ struct RoadStop {
 
 	static const int  cDebugCtorLevel =  3;  ///< Debug level on which Contructor / Destructor messages are printed
 	static const uint LIMIT           = 16;  ///< The maximum amount of roadstops that are allowed at a single station
+	static const uint MAX_BAY_COUNT   =  2;  ///< The maximum number of loading bays
 
 	TileIndex        xy;                    ///< Position on the map
 	RoadStopID       index;                 ///< Global (i.e. pool-wide) index
-	byte             status;                ///< Current status of the Stop. Like which spot is taken. TODO - enumify this
+	byte             status;                ///< Current status of the Stop. Like which spot is taken. Access using *Bay and *Busy functions.
 	byte             num_vehicles;          ///< Number of vehicles currently slotted to this stop
 	struct RoadStop  *next;                 ///< Next stop of the given type at this station
 
@@ -62,6 +63,13 @@ struct RoadStop {
 	void operator delete(void *rs, int index);
 
 	bool IsValid() const;
+
+	/* For accessing status */
+	bool HasFreeBay() const;
+	uint AllocateBay();
+	void FreeBay(uint nr);
+	bool IsEntranceBusy() const;
+	void SetEntranceBusy(bool busy);
 protected:
 	static RoadStop *AllocateRaw(void);
 };

src/station_cmd.cpp

@@ -2278,25 +2278,17 @@ static uint32 VehicleEnter_Station(Vehicle *v, TileIndex tile, int x, int y)
 				/* Attempt to allocate a parking bay in a road stop */
 				RoadStop *rs = GetRoadStopByTile(tile, GetRoadStopType(tile));
 
-				/* rs->status bits 0 and 1 describe current the two parking spots.
+				/* Check if station is busy or if there are no free bays. */
-				 * 0 means occupied, 1 means free. */
+				if (rs->IsEntranceBusy() || !rs->HasFreeBay()) return 8;
-
-				// Check if station is busy or if there are no free bays.
-				if (HASBIT(rs->status, 7) || GB(rs->status, 0, 2) == 0)
-					return 8;
 
 				v->u.road.state += 32;
 
-				// if the first bay is free, allocate that, else the second bay must be free.
+				/* Allocate a bay and update the road state */
-				if (HASBIT(rs->status, 0)) {
+				uint bay_nr = rs->AllocateBay();
-					CLRBIT(rs->status, 0);
+				SB(v->u.road.state, 1, 1, bay_nr);
-				} else {
-					CLRBIT(rs->status, 1);
-					v->u.road.state += 2;
-				}
 
-				// mark the station as busy
+				/* Mark the station entrace as busy */
-				SETBIT(rs->status, 7);
+				rs->SetEntranceBusy(true);
 			}
 		}
 	}