Function UpdateSignalsInBuffer

src/signal.cpp:479–563

* Updates blocks in _globset buffer * * @param owner company whose signals we are updating * @return state of the first block from _globset * @pre Company::IsValidID(owner) */

 * @pre Company::IsValidID(owner)
 */
static SigSegState UpdateSignalsInBuffer(Owner owner)
{
	assert(Company::IsValidID(owner));

	bool first = true;  // first block?
	SigSegState state = SIGSEG_FREE; // value to return

	TileIndex tile = INVALID_TILE; // Stop GCC from complaining about a possibly uninitialized variable (issue #8280).
	DiagDirection dir = INVALID_DIAGDIR;

	while (_globset.Get(&tile, &dir)) {
		assert(_tbuset.IsEmpty());
		assert(_tbdset.IsEmpty());

		/* After updating signal, data stored are always MP_RAILWAY with signals.
		 * Other situations happen when data are from outside functions -
		 * modification of railbits (including both rail building and removal),
		 * train entering/leaving block, train leaving depot...
		 */
		switch (GetTileType(tile)) {
			case MP_TUNNELBRIDGE:
				/* 'optimization assert' - do not try to update signals when it is not needed */
				assert(GetTunnelBridgeTransportType(tile) == TRANSPORT_RAIL);
				assert(dir == INVALID_DIAGDIR || dir == ReverseDiagDir(GetTunnelBridgeDirection(tile)));
				_tbdset.Add(tile, INVALID_DIAGDIR);  // we can safely start from wormhole centre
				_tbdset.Add(GetOtherTunnelBridgeEnd(tile), INVALID_DIAGDIR);
				break;

			case MP_RAILWAY:
				if (IsRailDepot(tile)) {
					/* 'optimization assert' do not try to update signals in other cases */
					assert(dir == INVALID_DIAGDIR || dir == GetRailDepotDirection(tile));
					_tbdset.Add(tile, INVALID_DIAGDIR); // start from depot inside
					break;
				}
				[[fallthrough]];

			case MP_STATION:
			case MP_ROAD:
				if ((TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_RAIL, 0)) & _enterdir_to_trackbits[dir]) != TRACK_BIT_NONE) {
					/* only add to set when there is some 'interesting' track */
					_tbdset.Add(tile, dir);
					_tbdset.Add(tile + TileOffsByDiagDir(dir), ReverseDiagDir(dir));
					break;
				}
				[[fallthrough]];

			default:
				/* jump to next tile */
				tile = tile + TileOffsByDiagDir(dir);
				dir = ReverseDiagDir(dir);
				if ((TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_RAIL, 0)) & _enterdir_to_trackbits[dir]) != TRACK_BIT_NONE) {
					_tbdset.Add(tile, dir);
					break;
				}
				/* happens when removing a rail that wasn't connected at one or both sides */
				continue; // continue the while() loop
		}