# ai_rail.cpp

Go to the documentation of this file.

    00001 /* $Id$ */
    00002
    00003 /*
    00004  * This file is part of OpenTTD.
    00005  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
    00006  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    00007  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
    00008  */
    00009
    00012 #include "ai_rail.hpp"
    00013 #include "ai_map.hpp"
    00014 #include "ai_station.hpp"
    00015 #include "../../command_type.h"
    00016 #include "../../debug.h"
    00017 #include "../../station_base.h"
    00018 #include "../../company_func.h"
    00019 #include "../../newgrf_generic.h"
    00020 #include "../../newgrf_station.h"
    00021
    00022 /* static */ bool AIRail::IsRailTile(TileIndex tile)
    00023 {
    00024   if (!::IsValidTile(tile)) return false;
    00025
    00026   return (::IsTileType(tile, MP_RAILWAY) && !::IsRailDepot(tile)) ||
    00027       (::HasStationTileRail(tile) && !::IsStationTileBlocked(tile)) || ::IsLevelCrossingTile(tile);
    00028 }
    00029
    00030 /* static */ bool AIRail::IsLevelCrossingTile(TileIndex tile)
    00031 {
    00032   if (!::IsValidTile(tile)) return false;
    00033
    00034   return ::IsLevelCrossingTile(tile);
    00035 }
    00036
    00037 /* static */ bool AIRail::IsRailDepotTile(TileIndex tile)
    00038 {
    00039   if (!::IsValidTile(tile)) return false;
    00040
    00041   return ::IsRailDepotTile(tile);
    00042 }
    00043
    00044 /* static */ bool AIRail::IsRailStationTile(TileIndex tile)
    00045 {
    00046   if (!::IsValidTile(tile)) return false;
    00047
    00048   return ::IsRailStationTile(tile);
    00049 }
    00050
    00051 /* static */ bool AIRail::IsRailWaypointTile(TileIndex tile)
    00052 {
    00053   if (!::IsValidTile(tile)) return false;
    00054
    00055   return ::IsRailWaypointTile(tile);
    00056 }
    00057
    00058 /* static */ bool AIRail::IsRailTypeAvailable(RailType rail_type)
    00059 {
    00060   if ((::RailType)rail_type < RAILTYPE_BEGIN || (::RailType)rail_type >= RAILTYPE_END) return false;
    00061
    00062   return ::HasRailtypeAvail(_current_company, (::RailType)rail_type);
    00063 }
    00064
    00065 /* static */ AIRail::RailType AIRail::GetCurrentRailType()
    00066 {
    00067   return (RailType)AIObject::GetRailType();
    00068 }
    00069
    00070 /* static */ void AIRail::SetCurrentRailType(RailType rail_type)
    00071 {
    00072   if (!IsRailTypeAvailable(rail_type)) return;
    00073
    00074   AIObject::SetRailType((::RailType)rail_type);
    00075 }
    00076
    00077 /* static */ bool AIRail::TrainCanRunOnRail(AIRail::RailType engine_rail_type, AIRail::RailType track_rail_type)
    00078 {
    00079   if (!AIRail::IsRailTypeAvailable(engine_rail_type)) return false;
    00080   if (!AIRail::IsRailTypeAvailable(track_rail_type)) return false;
    00081
    00082   return ::IsCompatibleRail((::RailType)engine_rail_type, (::RailType)track_rail_type);
    00083 }
    00084
    00085 /* static */ bool AIRail::TrainHasPowerOnRail(AIRail::RailType engine_rail_type, AIRail::RailType track_rail_type)
    00086 {\
    00087   if (!AIRail::IsRailTypeAvailable(engine_rail_type)) return false;
    00088   if (!AIRail::IsRailTypeAvailable(track_rail_type)) return false;
    00089
    00090   return ::HasPowerOnRail((::RailType)engine_rail_type, (::RailType)track_rail_type);
    00091 }
    00092
    00093 /* static */ AIRail::RailType AIRail::GetRailType(TileIndex tile)
    00094 {
    00095   if (!AITile::HasTransportType(tile, AITile::TRANSPORT_RAIL)) return RAILTYPE_INVALID;
    00096
    00097   return (RailType)::GetRailType(tile);
    00098 }
    00099
    00100 /* static */ bool AIRail::ConvertRailType(TileIndex start_tile, TileIndex end_tile, AIRail::RailType convert_to)
    00101 {
    00102   EnforcePrecondition(false, ::IsValidTile(start_tile));
    00103   EnforcePrecondition(false, ::IsValidTile(end_tile));
    00104   EnforcePrecondition(false, IsRailTypeAvailable(convert_to));
    00105
    00106   return AIObject::DoCommand(start_tile, end_tile, convert_to, CMD_CONVERT_RAIL);
    00107 }
    00108
    00109 /* static */ TileIndex AIRail::GetRailDepotFrontTile(TileIndex depot)
    00110 {
    00111   if (!IsRailDepotTile(depot)) return INVALID_TILE;
    00112
    00113   return depot + ::TileOffsByDiagDir(::GetRailDepotDirection(depot));
    00114 }
    00115
    00116 /* static */ AIRail::RailTrack AIRail::GetRailStationDirection(TileIndex tile)
    00117 {
    00118   if (!IsRailStationTile(tile)) return RAILTRACK_INVALID;
    00119
    00120   return (RailTrack)::GetRailStationTrackBits(tile);
    00121 }
    00122
    00123 /* static */ bool AIRail::BuildRailDepot(TileIndex tile, TileIndex front)
    00124 {
    00125   EnforcePrecondition(false, tile != front);
    00126   EnforcePrecondition(false, ::IsValidTile(tile));
    00127   EnforcePrecondition(false, ::IsValidTile(front));
    00128   EnforcePrecondition(false, ::TileX(tile) == ::TileX(front) || ::TileY(tile) == ::TileY(front));
    00129   EnforcePrecondition(false, IsRailTypeAvailable(GetCurrentRailType()));
    00130
    00131   uint entrance_dir = (::TileX(tile) == ::TileX(front)) ? (::TileY(tile) < ::TileY(front) ? 1 : 3) : (::TileX(tile) < ::TileX(front) ? 2 : 0);
    00132
    00133   return AIObject::DoCommand(tile, AIObject::GetRailType(), entrance_dir, CMD_BUILD_TRAIN_DEPOT);
    00134 }
    00135
    00136 /* static */ bool AIRail::BuildRailStation(TileIndex tile, RailTrack direction, uint num_platforms, uint platform_length, StationID station_id)
    00137 {
    00138   EnforcePrecondition(false, ::IsValidTile(tile));
    00139   EnforcePrecondition(false, direction == RAILTRACK_NW_SE || direction == RAILTRACK_NE_SW);
    00140   EnforcePrecondition(false, num_platforms > 0 && num_platforms <= 0xFF);
    00141   EnforcePrecondition(false, platform_length > 0 && platform_length <= 0xFF);
    00142   EnforcePrecondition(false, IsRailTypeAvailable(GetCurrentRailType()));
    00143   EnforcePrecondition(false, station_id == AIStation::STATION_NEW || station_id == AIStation::STATION_JOIN_ADJACENT || AIStation::IsValidStation(station_id));
    00144
    00145   uint32 p1 = GetCurrentRailType() | (platform_length << 16) | (num_platforms << 8);
    00146   if (direction == RAILTRACK_NW_SE) p1 |= (1 << 4);
    00147   if (station_id != AIStation::STATION_JOIN_ADJACENT) p1 |= (1 << 24);
    00148   return AIObject::DoCommand(tile, p1, (AIStation::IsValidStation(station_id) ? station_id : INVALID_STATION) << 16, CMD_BUILD_RAIL_STATION);
    00149 }
    00150
    00151 /* static */ bool AIRail::BuildNewGRFRailStation(TileIndex tile, RailTrack direction, uint num_platforms, uint platform_length, StationID station_id, CargoID cargo_id, IndustryType source_industry, IndustryType goal_industry, int distance, bool source_station)
    00152 {
    00153   EnforcePrecondition(false, ::IsValidTile(tile));
    00154   EnforcePrecondition(false, direction == RAILTRACK_NW_SE || direction == RAILTRACK_NE_SW);
    00155   EnforcePrecondition(false, num_platforms > 0 && num_platforms <= 0xFF);
    00156   EnforcePrecondition(false, platform_length > 0 && platform_length <= 0xFF);
    00157   EnforcePrecondition(false, IsRailTypeAvailable(GetCurrentRailType()));
    00158   EnforcePrecondition(false, station_id == AIStation::STATION_NEW || station_id == AIStation::STATION_JOIN_ADJACENT || AIStation::IsValidStation(station_id));
    00159
    00160   uint32 p1 = GetCurrentRailType() | (platform_length << 16) | (num_platforms << 8);
    00161   if (direction == RAILTRACK_NW_SE) p1 |= 1 << 4;
    00162   if (station_id != AIStation::STATION_JOIN_ADJACENT) p1 |= (1 << 24);
    00163
    00164   const GRFFile *file;
    00165   uint16 res = GetAiPurchaseCallbackResult(GSF_STATION, cargo_id, 0, source_industry, goal_industry, min(255, distance / 2), AICE_STATION_GET_STATION_ID, source_station ? 0 : 1, min(15, num_platforms) << 4 | min(15, platform_length), &file);
    00166   uint32 p2 = (AIStation::IsValidStation(station_id) ? station_id : INVALID_STATION) << 16;
    00167   if (res != CALLBACK_FAILED) {
    00168     int index = 0;
    00169     const StationSpec *spec = GetCustomStationSpecByGrf(file->grfid, res, &index);
    00170     if (spec == NULL) {
    00171       DEBUG(grf, 1, "%s returned an invalid station ID for 'AI construction/purchase selection (18)' callback", file->filename);
    00172     } else {
    00173       p2 |= spec->sclass | index << 8;
    00174     }
    00175
    00176   }
    00177   return AIObject::DoCommand(tile, p1, p2, CMD_BUILD_RAIL_STATION);
    00178 }
    00179
    00180 /* static */ bool AIRail::BuildRailWaypoint(TileIndex tile)
    00181 {
    00182   EnforcePrecondition(false, ::IsValidTile(tile));
    00183   EnforcePrecondition(false, IsRailTile(tile));
    00184   EnforcePrecondition(false, GetRailTracks(tile) == RAILTRACK_NE_SW || GetRailTracks(tile) == RAILTRACK_NW_SE);
    00185   EnforcePrecondition(false, IsRailTypeAvailable(GetCurrentRailType()));
    00186
    00187   return AIObject::DoCommand(tile, GetCurrentRailType() | (GetRailTracks(tile) == RAILTRACK_NE_SW ? AXIS_X : AXIS_Y) << 4 | 1 << 8 | 1 << 16, STAT_CLASS_WAYP | INVALID_STATION << 16, CMD_BUILD_RAIL_WAYPOINT);
    00188 }
    00189
    00190 /* static */ bool AIRail::RemoveRailWaypointTileRectangle(TileIndex tile, TileIndex tile2, bool keep_rail)
    00191 {
    00192   EnforcePrecondition(false, ::IsValidTile(tile));
    00193   EnforcePrecondition(false, ::IsValidTile(tile2));
    00194
    00195   return AIObject::DoCommand(tile, tile2, keep_rail ? 1 : 0, CMD_REMOVE_FROM_RAIL_WAYPOINT);
    00196 }
    00197
    00198 /* static */ bool AIRail::RemoveRailStationTileRectangle(TileIndex tile, TileIndex tile2, bool keep_rail)
    00199 {
    00200   EnforcePrecondition(false, ::IsValidTile(tile));
    00201   EnforcePrecondition(false, ::IsValidTile(tile2));
    00202
    00203   return AIObject::DoCommand(tile, tile2, keep_rail ? 1 : 0, CMD_REMOVE_FROM_RAIL_STATION);
    00204 }
    00205
    00206 /* static */ uint AIRail::GetRailTracks(TileIndex tile)
    00207 {
    00208   if (!IsRailTile(tile)) return RAILTRACK_INVALID;
    00209
    00210   if (IsRailStationTile(tile) || IsRailWaypointTile(tile)) return ::TrackToTrackBits(::GetRailStationTrack(tile));
    00211   if (IsLevelCrossingTile(tile)) return ::GetCrossingRailBits(tile);
    00212   if (IsRailDepotTile(tile)) return ::TRACK_BIT_NONE;
    00213   return ::GetTrackBits(tile);
    00214 }
    00215
    00216 /* static */ bool AIRail::BuildRailTrack(TileIndex tile, RailTrack rail_track)
    00217 {
    00218   EnforcePrecondition(false, ::IsValidTile(tile));
    00219   EnforcePrecondition(false, rail_track != 0);
    00220   EnforcePrecondition(false, (rail_track & ~::TRACK_BIT_ALL) == 0);
    00221   EnforcePrecondition(false, KillFirstBit((uint)rail_track) == 0);
    00222   EnforcePrecondition(false, IsRailTypeAvailable(GetCurrentRailType()));
    00223
    00224   return AIObject::DoCommand(tile, tile, GetCurrentRailType() | (FindFirstTrack((::TrackBits)rail_track) << 4), CMD_BUILD_RAILROAD_TRACK);
    00225 }
    00226
    00227 /* static */ bool AIRail::RemoveRailTrack(TileIndex tile, RailTrack rail_track)
    00228 {
    00229   EnforcePrecondition(false, ::IsValidTile(tile));
    00230   EnforcePrecondition(false, ::IsPlainRailTile(tile) || ::IsLevelCrossingTile(tile));
    00231   EnforcePrecondition(false, GetRailTracks(tile) & rail_track);
    00232   EnforcePrecondition(false, KillFirstBit((uint)rail_track) == 0);
    00233
    00234   return AIObject::DoCommand(tile, tile, GetCurrentRailType() | (FindFirstTrack((::TrackBits)rail_track) << 4), CMD_REMOVE_RAILROAD_TRACK);
    00235 }
    00236
    00237 /* static */ bool AIRail::AreTilesConnected(TileIndex from, TileIndex tile, TileIndex to)
    00238 {
    00239   if (!IsRailTile(tile)) return false;
    00240   if (from == to || AIMap::DistanceManhattan(from, tile) != 1 || AIMap::DistanceManhattan(tile, to) != 1) return false;
    00241
    00242   if (to < from) ::Swap(from, to);
    00243
    00244   if (tile - from == 1) {
    00245     if (to - tile == 1) return (GetRailTracks(tile) & RAILTRACK_NE_SW) != 0;
    00246     if (to - tile == ::MapSizeX()) return (GetRailTracks(tile) & RAILTRACK_NE_SE) != 0;
    00247   } else if (tile - from == ::MapSizeX()) {
    00248     if (tile - to == 1) return (GetRailTracks(tile) & RAILTRACK_NW_NE) != 0;
    00249     if (to - tile == 1) return (GetRailTracks(tile) & RAILTRACK_NW_SW) != 0;
    00250     if (to - tile == ::MapSizeX()) return (GetRailTracks(tile) & RAILTRACK_NW_SE) != 0;
    00251   } else {
    00252     return (GetRailTracks(tile) & RAILTRACK_SW_SE) != 0;
    00253   }
    00254
    00255   NOT_REACHED();
    00256 }
    00257
    00262 static uint32 SimulateDrag(TileIndex from, TileIndex tile, TileIndex *to)
    00263 {
    00264   int diag_offset = abs(abs((int)::TileX(*to) - (int)::TileX(tile)) - abs((int)::TileY(*to) - (int)::TileY(tile)));
    00265   uint32 p2 = AIRail::GetCurrentRailType();
    00266   if (::TileY(from) == ::TileY(*to)) {
    00267     p2 |= (TRACK_X << 4);
    00268     *to -= Clamp((int)::TileX(*to) - (int)::TileX(tile), -1, 1);
    00269   } else if (::TileX(from) == ::TileX(*to)) {
    00270     p2 |= (TRACK_Y << 4);
    00271     *to -= ::MapSizeX() * Clamp((int)::TileY(*to) - (int)::TileY(tile), -1, 1);
    00272   } else if (::TileY(from) < ::TileY(tile)) {
    00273     if (::TileX(*to) < ::TileX(tile)) {
    00274       p2 |= (TRACK_UPPER << 4);
    00275     } else {
    00276       p2 |= (TRACK_LEFT << 4);
    00277     }
    00278     if (diag_offset) {
    00279       *to -= Clamp((int)::TileX(*to) - (int)::TileX(tile), -1, 1);
    00280     } else {
    00281       *to -= ::MapSizeX() * Clamp((int)::TileY(*to) - (int)::TileY(tile), -1, 1);
    00282     }
    00283   } else if (::TileY(from) > ::TileY(tile)) {
    00284     if (::TileX(*to) < ::TileX(tile)) {
    00285       p2 |= (TRACK_RIGHT << 4);
    00286     } else {
    00287       p2 |= (TRACK_LOWER << 4);
    00288     }
    00289     if (diag_offset) {
    00290       *to -= Clamp((int)::TileX(*to) - (int)::TileX(tile), -1, 1);
    00291     } else {
    00292       *to -= ::MapSizeX() * Clamp((int)::TileY(*to) - (int)::TileY(tile), -1, 1);
    00293     }
    00294   } else if (::TileX(from) < ::TileX(tile)) {
    00295     if (::TileY(*to) < ::TileY(tile)) {
    00296       p2 |= (TRACK_UPPER << 4);
    00297     } else {
    00298       p2 |= (TRACK_RIGHT << 4);
    00299     }
    00300     if (!diag_offset) {
    00301       *to -= Clamp((int)::TileX(*to) - (int)::TileX(tile), -1, 1);
    00302     } else {
    00303       *to -= ::MapSizeX() * Clamp((int)::TileY(*to) - (int)::TileY(tile), -1, 1);
    00304     }
    00305   } else if (::TileX(from) > ::TileX(tile)) {
    00306     if (::TileY(*to) < ::TileY(tile)) {
    00307       p2 |= (TRACK_LEFT << 4);
    00308     } else {
    00309       p2 |= (TRACK_LOWER << 4);
    00310     }
    00311     if (!diag_offset) {
    00312       *to -= Clamp((int)::TileX(*to) - (int)::TileX(tile), -1, 1);
    00313     } else {
    00314       *to -= ::MapSizeX() * Clamp((int)::TileY(*to) - (int)::TileY(tile), -1, 1);
    00315     }
    00316   }
    00317   return p2;
    00318 }
    00319
    00320 /* static */ bool AIRail::BuildRail(TileIndex from, TileIndex tile, TileIndex to)
    00321 {
    00322   EnforcePrecondition(false, ::IsValidTile(from));
    00323   EnforcePrecondition(false, ::IsValidTile(tile));
    00324   EnforcePrecondition(false, ::IsValidTile(to));
    00325   EnforcePrecondition(false, ::DistanceManhattan(from, tile) == 1);
    00326   EnforcePrecondition(false, ::DistanceManhattan(tile, to) >= 1);
    00327   EnforcePrecondition(false, IsRailTypeAvailable(GetCurrentRailType()));
    00328   int diag_offset = abs(abs((int)::TileX(to) - (int)::TileX(tile)) - abs((int)::TileY(to) - (int)::TileY(tile)));
    00329   EnforcePrecondition(false, diag_offset <= 1 ||
    00330       (::TileX(from) == ::TileX(tile) && ::TileX(tile) == ::TileX(to)) ||
    00331       (::TileY(from) == ::TileY(tile) && ::TileY(tile) == ::TileY(to)));
    00332
    00333   uint32 p2 = SimulateDrag(from, tile, &to);
    00334   return AIObject::DoCommand(tile, to, p2, CMD_BUILD_RAILROAD_TRACK);
    00335 }
    00336
    00337 /* static */ bool AIRail::RemoveRail(TileIndex from, TileIndex tile, TileIndex to)
    00338 {
    00339   EnforcePrecondition(false, ::IsValidTile(from));
    00340   EnforcePrecondition(false, ::IsValidTile(tile));
    00341   EnforcePrecondition(false, ::IsValidTile(to));
    00342   EnforcePrecondition(false, ::DistanceManhattan(from, tile) == 1);
    00343   EnforcePrecondition(false, ::DistanceManhattan(tile, to) >= 1);
    00344   int diag_offset = abs(abs((int)::TileX(to) - (int)::TileX(tile)) - abs((int)::TileY(to) - (int)::TileY(tile)));
    00345   EnforcePrecondition(false, diag_offset <= 1 ||
    00346       (::TileX(from) == ::TileX(tile) && ::TileX(tile) == ::TileX(to)) ||
    00347       (::TileY(from) == ::TileY(tile) && ::TileY(tile) == ::TileY(to)));
    00348
    00349   if (!IsRailTypeAvailable(GetCurrentRailType())) SetCurrentRailType(GetRailType(tile));
    00350   uint32 p2 = SimulateDrag(from, tile, &to);
    00351   return AIObject::DoCommand(tile, to, p2, CMD_REMOVE_RAILROAD_TRACK);
    00352 }
    00353
    00358 struct AIRailSignalData {
    00359   Track track;
    00360   Trackdir trackdir;
    00361   uint signal_cycles;
    00362 };
    00363
    00364 static const int NUM_TRACK_DIRECTIONS = 3;
    00365
    00372 static const AIRailSignalData _possible_trackdirs[5][NUM_TRACK_DIRECTIONS] = {
    00373   {{TRACK_UPPER,   TRACKDIR_UPPER_E, 0}, {TRACK_Y,       TRACKDIR_Y_SE,    0}, {TRACK_LEFT,    TRACKDIR_LEFT_S,  1}},
    00374   {{TRACK_RIGHT,   TRACKDIR_RIGHT_S, 1}, {TRACK_X,       TRACKDIR_X_SW,    1}, {TRACK_UPPER,   TRACKDIR_UPPER_W, 1}},
    00375   {{INVALID_TRACK, INVALID_TRACKDIR, 0}, {INVALID_TRACK, INVALID_TRACKDIR, 0}, {INVALID_TRACK, INVALID_TRACKDIR, 0}},
    00376   {{TRACK_LOWER,   TRACKDIR_LOWER_E, 0}, {TRACK_X,       TRACKDIR_X_NE,    0}, {TRACK_LEFT,    TRACKDIR_LEFT_N,  0}},
    00377   {{TRACK_RIGHT,   TRACKDIR_RIGHT_N, 0}, {TRACK_Y,       TRACKDIR_Y_NW,    1}, {TRACK_LOWER,   TRACKDIR_LOWER_W, 1}}
    00378 };
    00379
    00380 /* static */ AIRail::SignalType AIRail::GetSignalType(TileIndex tile, TileIndex front)
    00381 {
    00382   if (AIMap::DistanceManhattan(tile, front) != 1) return SIGNALTYPE_NONE;
    00383   if (!::IsTileType(tile, MP_RAILWAY) || !::HasSignals(tile)) return SIGNALTYPE_NONE;
    00384
    00385   int data_index = 2 + (::TileX(front) - ::TileX(tile)) + 2 * (::TileY(front) - ::TileY(tile));
    00386
    00387   for (int i = 0; i < NUM_TRACK_DIRECTIONS; i++) {
    00388     const Track &track = _possible_trackdirs[data_index][i].track;
    00389     if (!(::TrackToTrackBits(track) & GetRailTracks(tile))) continue;
    00390     if (!HasSignalOnTrack(tile, track)) continue;
    00391     if (!HasSignalOnTrackdir(tile, _possible_trackdirs[data_index][i].trackdir)) continue;
    00392     SignalType st = (SignalType)::GetSignalType(tile, track);
    00393     if (HasSignalOnTrackdir(tile, ::ReverseTrackdir(_possible_trackdirs[data_index][i].trackdir))) st = (SignalType)(st | SIGNALTYPE_TWOWAY);
    00394     return st;
    00395   }
    00396
    00397   return SIGNALTYPE_NONE;
    00398 }
    00399
    00403 static bool IsValidSignalType(int signal_type)
    00404 {
    00405   if (signal_type < AIRail::SIGNALTYPE_NORMAL || signal_type > AIRail::SIGNALTYPE_COMBO_TWOWAY) return false;
    00406   if (signal_type > AIRail::SIGNALTYPE_PBS_ONEWAY && signal_type < AIRail::SIGNALTYPE_NORMAL_TWOWAY) return false;
    00407   return true;
    00408 }
    00409
    00410 /* static */ bool AIRail::BuildSignal(TileIndex tile, TileIndex front, SignalType signal)
    00411 {
    00412   EnforcePrecondition(false, AIMap::DistanceManhattan(tile, front) == 1)
    00413   EnforcePrecondition(false, ::IsPlainRailTile(tile));
    00414   EnforcePrecondition(false, ::IsValidSignalType(signal));
    00415
    00416   Track track = INVALID_TRACK;
    00417   uint signal_cycles;
    00418
    00419   int data_index = 2 + (::TileX(front) - ::TileX(tile)) + 2 * (::TileY(front) - ::TileY(tile));
    00420   for (int i = 0; i < NUM_TRACK_DIRECTIONS; i++) {
    00421     const Track &t = _possible_trackdirs[data_index][i].track;
    00422     if (!(::TrackToTrackBits(t) & GetRailTracks(tile))) continue;
    00423     track = t;
    00424     signal_cycles = _possible_trackdirs[data_index][i].signal_cycles;
    00425     break;
    00426   }
    00427   EnforcePrecondition(false, track != INVALID_TRACK);
    00428
    00429   uint p1 = track;
    00430   if (signal < SIGNALTYPE_TWOWAY) {
    00431     if (signal != SIGNALTYPE_PBS && signal != SIGNALTYPE_PBS_ONEWAY) signal_cycles++;
    00432     p1 |= (signal_cycles << 15);
    00433   }
    00434   p1 |= ((signal >= SIGNALTYPE_TWOWAY ? signal ^ SIGNALTYPE_TWOWAY : signal) << 5);
    00435
    00436   return AIObject::DoCommand(tile, p1, 0, CMD_BUILD_SIGNALS);
    00437 }
    00438
    00439 /* static */ bool AIRail::RemoveSignal(TileIndex tile, TileIndex front)
    00440 {
    00441   EnforcePrecondition(false, AIMap::DistanceManhattan(tile, front) == 1)
    00442   EnforcePrecondition(false, GetSignalType(tile, front) != SIGNALTYPE_NONE);
    00443
    00444   Track track = INVALID_TRACK;
    00445   int data_index = 2 + (::TileX(front) - ::TileX(tile)) + 2 * (::TileY(front) - ::TileY(tile));
    00446   for (int i = 0; i < NUM_TRACK_DIRECTIONS; i++) {
    00447     const Track &t = _possible_trackdirs[data_index][i].track;
    00448     if (!(::TrackToTrackBits(t) & GetRailTracks(tile))) continue;
    00449     track = t;
    00450     break;
    00451   }
    00452   EnforcePrecondition(false, track != INVALID_TRACK);
    00453
    00454   return AIObject::DoCommand(tile, track, 0, CMD_REMOVE_SIGNALS);
    00455 }