Files @ r3877:c0e9cf5b0329
Branch filter:

Location: cpp/openttd-patchpack/source/rail_cmd.c

tron
(svn r4920) Remove parameters, which get only used in certain functions, by splitting those functions.
At least in the case of checking for oil industry restrictions this makes the check conditions more clear.
   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
/* $Id$ */

#include "stdafx.h"
#include "openttd.h"
#include "bridge_map.h"
#include "debug.h"
#include "functions.h"
#include "rail_map.h"
#include "road_map.h"
#include "table/sprites.h"
#include "table/strings.h"
#include "map.h"
#include "tile.h"
#include "town_map.h"
#include "tunnel_map.h"
#include "vehicle.h"
#include "viewport.h"
#include "command.h"
#include "pathfind.h"
#include "engine.h"
#include "town.h"
#include "sound.h"
#include "station.h"
#include "sprite.h"
#include "depot.h"
#include "waypoint.h"
#include "rail.h"
#include "railtypes.h" // include table for railtypes
#include "newgrf.h"
#include "newgrf_callbacks.h"
#include "newgrf_station.h"

const byte _track_sloped_sprites[14] = {
	14, 15, 22, 13,
	 0, 21, 17, 12,
	23,  0, 18, 20,
	19, 16
};

void ShowTrainDepotWindow(TileIndex tile);

/*         4
 *     ---------
 *    |\       /|
 *    | \    1/ |
 *    |  \   /  |
 *    |   \ /   |
 *  16|    \    |32
 *    |   / \2  |
 *    |  /   \  |
 *    | /     \ |
 *    |/       \|
 *     ---------
 *         8
 */



/* MAP2 byte:    abcd???? => Signal On? Same coding as map3lo
 * MAP3LO byte:  abcd???? => Signal Exists?
 *				 a and b are for diagonals, upper and left,
 *				 one for each direction. (ie a == NE->SW, b ==
 *				 SW->NE, or v.v., I don't know. b and c are
 *				 similar for lower and right.
 * MAP2 byte:    ????abcd => Type of ground.
 * MAP3LO byte:  ????abcd => Type of rail.
 * MAP5:         00abcdef => rail
 *               01abcdef => rail w/ signals
 *               10uuuuuu => unused
 *               11uuuudd => rail depot
 */

static bool CheckTrackCombination(TileIndex tile, TrackBits to_build, uint flags)
{
	RailTileType type = GetRailTileType(tile);
	TrackBits current; /* The current track layout */
	TrackBits future; /* The track layout we want to build */
	_error_message = STR_1001_IMPOSSIBLE_TRACK_COMBINATION;

	if (type != RAIL_TILE_NORMAL && type != RAIL_TILE_SIGNALS)
		return false; /* Cannot build anything on depots and checkpoints */

	/* So, we have a tile with tracks on it (and possibly signals). Let's see
	 * what tracks first */
	current = GetTrackBits(tile);
	future = current | to_build;

	/* Are we really building something new? */
	if (current == future) {
		/* Nothing new is being built */
		_error_message = STR_1007_ALREADY_BUILT;
		return false;
	}

	/* Let's see if we may build this */
	if ((flags & DC_NO_RAIL_OVERLAP) || type == RAIL_TILE_SIGNALS) {
		/* If we are not allowed to overlap (flag is on for ai players or we have
		 * signals on the tile), check that */
		return future == TRACK_BIT_HORZ || future == TRACK_BIT_VERT;
	} else {
		/* Normally, we may overlap and any combination is valid */
		return true;
	}
}


const TrackBits _valid_tileh_slopes[2][15] = {

// set of normal ones
{
	TRACK_BIT_ALL,
	TRACK_BIT_RIGHT,
	TRACK_BIT_UPPER,
	TRACK_BIT_X,

	TRACK_BIT_LEFT,
	0,
	TRACK_BIT_Y,
	TRACK_BIT_LOWER,

	TRACK_BIT_LOWER,
	TRACK_BIT_Y,
	0,
	TRACK_BIT_LEFT,

	TRACK_BIT_X,
	TRACK_BIT_UPPER,
	TRACK_BIT_RIGHT,
},

// allowed rail for an evenly raised platform
{
	0,
	TRACK_BIT_LEFT,
	TRACK_BIT_LOWER,
	TRACK_BIT_Y | TRACK_BIT_LOWER | TRACK_BIT_LEFT,

	TRACK_BIT_RIGHT,
	TRACK_BIT_ALL,
	TRACK_BIT_X | TRACK_BIT_LOWER | TRACK_BIT_RIGHT,
	TRACK_BIT_ALL,

	TRACK_BIT_UPPER,
	TRACK_BIT_X | TRACK_BIT_UPPER | TRACK_BIT_LEFT,
	TRACK_BIT_ALL,
	TRACK_BIT_ALL,

	TRACK_BIT_Y | TRACK_BIT_UPPER | TRACK_BIT_RIGHT,
	TRACK_BIT_ALL,
	TRACK_BIT_ALL
}
};

uint GetRailFoundation(Slope tileh, TrackBits bits)
{
	int i;

	if ((~_valid_tileh_slopes[0][tileh] & bits) == 0)
		return 0;

	if ((~_valid_tileh_slopes[1][tileh] & bits) == 0)
		return tileh;

	if ((
				(i  = 0, tileh == SLOPE_W) ||
				(i += 2, tileh == SLOPE_S) ||
				(i += 2, tileh == SLOPE_E) ||
				(i += 2, tileh == SLOPE_N)
			) && (
				bits == TRACK_BIT_X ||
				(i++, bits == TRACK_BIT_Y)
			)) {
		return i + 15;
	} else {
		return 0;
	}
}


static uint32 CheckRailSlope(Slope tileh, TrackBits rail_bits, TrackBits existing, TileIndex tile)
{
	// never allow building on top of steep tiles
	if (!IsSteepSlope(tileh)) {
		rail_bits |= existing;

		// don't allow building on the lower side of a coast
		if (IsTileType(tile, MP_WATER) &&
				~_valid_tileh_slopes[1][tileh] & rail_bits) {
			return_cmd_error(STR_3807_CAN_T_BUILD_ON_WATER);
		}

		// no special foundation
		if ((~_valid_tileh_slopes[0][tileh] & rail_bits) == 0)
			return 0;

		if ((~_valid_tileh_slopes[1][tileh] & rail_bits) == 0 || ( // whole tile is leveled up
					(rail_bits == TRACK_BIT_X || rail_bits == TRACK_BIT_Y) &&
					(tileh == SLOPE_W || tileh == SLOPE_S || tileh == SLOPE_E || tileh == SLOPE_N)
				)) { // partly up
			if (existing != 0) {
				return 0;
			} else if (!_patches.build_on_slopes || _is_old_ai_player) {
				return_cmd_error(STR_1000_LAND_SLOPED_IN_WRONG_DIRECTION);
			} else {
				return _price.terraform;
			}
		}
	}
	return_cmd_error(STR_1000_LAND_SLOPED_IN_WRONG_DIRECTION);
}

/* Validate functions for rail building */
static inline bool ValParamTrackOrientation(Track track) {return IsValidTrack(track);}

/** Build a single piece of rail
 * @param tile tile  to build on
 * @param p1 railtype of being built piece (normal, mono, maglev)
 * @param p2 rail track to build
 */
int32 CmdBuildSingleRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	Slope tileh;
	Track track = (Track)p2;
	TrackBits trackbit;
	int32 cost = 0;
	int32 ret;

	if (!ValParamRailtype(p1) || !ValParamTrackOrientation(track)) return CMD_ERROR;

	tileh = GetTileSlope(tile, NULL);
	trackbit = TrackToTrackBits(track);

	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	switch (GetTileType(tile)) {
		case MP_TUNNELBRIDGE:
			if (!IsBridge(tile) ||
					!IsBridgeMiddle(tile) ||
					(GetBridgeAxis(tile) == AXIS_X ? TRACK_BIT_Y : TRACK_BIT_X) != trackbit) {
				// Get detailed error message
				return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
			}

			if (IsClearUnderBridge(tile)) {
				ret = CheckRailSlope(tileh, trackbit, 0, tile);
				if (CmdFailed(ret)) return ret;
				cost += ret;

				if (flags & DC_EXEC) SetRailUnderBridge(tile, _current_player, p1);
			} else if (IsTransportUnderBridge(tile) &&
					GetTransportTypeUnderBridge(tile) == TRANSPORT_RAIL) {
				return_cmd_error(STR_1007_ALREADY_BUILT);
			} else {
				// Get detailed error message
				return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
			}
			break;

		case MP_RAILWAY:
			if (!CheckTrackCombination(tile, trackbit, flags) ||
					!EnsureNoVehicle(tile)) {
				return CMD_ERROR;
			}
			if (GetRailTileType(tile) == RAIL_TILE_DEPOT_WAYPOINT ||
					!IsTileOwner(tile, _current_player) ||
					GetRailType(tile) != p1) {
				// Get detailed error message
				return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
			}

			ret = CheckRailSlope(tileh, trackbit, GetTrackBits(tile), tile);
			if (CmdFailed(ret)) return ret;
			cost += ret;

			if (flags & DC_EXEC) {
				SetRailGroundType(tile, RAIL_GROUND_BARREN);
				_m[tile].m5 |= trackbit;
			}
			break;

		case MP_STREET:
#define M(x) (1 << (x))
			/* Level crossings may only be built on these slopes */
			if (!HASBIT(M(SLOPE_SEN) | M(SLOPE_ENW) | M(SLOPE_NWS) | M(SLOPE_NS) | M(SLOPE_WSE) | M(SLOPE_EW) | M(SLOPE_FLAT), tileh)) {
				return_cmd_error(STR_1000_LAND_SLOPED_IN_WRONG_DIRECTION);
			}
#undef M

			if (!EnsureNoVehicle(tile)) return CMD_ERROR;

			if (GetRoadTileType(tile) == ROAD_TILE_NORMAL && (
						(track == TRACK_X && GetRoadBits(tile) == ROAD_Y) ||
						(track == TRACK_Y && GetRoadBits(tile) == ROAD_X)
					)) {
				if (flags & DC_EXEC) {
					MakeRoadCrossing(tile, GetTileOwner(tile), _current_player, (track == TRACK_X ? AXIS_Y : AXIS_X), p1, GetTownIndex(tile));
				}
				break;
			}

			if (IsLevelCrossing(tile) && GetCrossingRailBits(tile) == trackbit) {
				return_cmd_error(STR_1007_ALREADY_BUILT);
			}
			/* FALLTHROUGH */

		default:
			ret = CheckRailSlope(tileh, trackbit, 0, tile);
			if (CmdFailed(ret)) return ret;
			cost += ret;

			ret = DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
			if (CmdFailed(ret)) return ret;
			cost += ret;

			if (flags & DC_EXEC) MakeRailNormal(tile, _current_player, trackbit, p1);
			break;
	}

	if (flags & DC_EXEC) {
		MarkTileDirtyByTile(tile);
		SetSignalsOnBothDir(tile, track);
	}

	return cost + _price.build_rail;
}

/** Remove a single piece of track
 * @param tile tile to remove track from
 * @param p1 unused
 * @param p2 rail orientation
 */
int32 CmdRemoveSingleRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	Track track = (Track)p2;
	TrackBits trackbit;
	int32 cost = _price.remove_rail;
	bool crossing = false;

	if (!ValParamTrackOrientation(p2)) return CMD_ERROR;
	trackbit = TrackToTrackBits(track);

	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	switch (GetTileType(tile)) {
		case MP_TUNNELBRIDGE:
			if (!IsBridge(tile) ||
					!IsBridgeMiddle(tile) ||
					!IsTransportUnderBridge(tile) ||
					GetTransportTypeUnderBridge(tile) != TRANSPORT_RAIL ||
					GetRailBitsUnderBridge(tile) != trackbit ||
					(_current_player != OWNER_WATER && !CheckTileOwnership(tile)) ||
					!EnsureNoVehicleOnGround(tile)) {
				return CMD_ERROR;
			}

			if (flags & DC_EXEC) SetClearUnderBridge(tile);
			break;

		case MP_STREET: {
			if (!IsLevelCrossing(tile) ||
					GetCrossingRailBits(tile) != trackbit ||
					(_current_player != OWNER_WATER && !CheckTileOwnership(tile)) ||
					!EnsureNoVehicle(tile)) {
				return CMD_ERROR;
			}

			if (flags & DC_EXEC) {
				MakeRoadNormal(tile, GetCrossingRoadOwner(tile), GetCrossingRoadBits(tile), GetTownIndex(tile));
			}
			break;
		}

		case MP_RAILWAY: {
			TrackBits present;

			if (!IsPlainRailTile(tile) ||
					(_current_player != OWNER_WATER && !CheckTileOwnership(tile)) ||
					!EnsureNoVehicle(tile)) {
				return CMD_ERROR;
			}

			present = GetTrackBits(tile);
			if ((present & trackbit) == 0) return CMD_ERROR;
			if (present == (TRACK_BIT_X | TRACK_BIT_Y)) crossing = true;

			/* Charge extra to remove signals on the track, if they are there */
			if (HasSignalOnTrack(tile, track))
				cost += DoCommand(tile, track, 0, flags, CMD_REMOVE_SIGNALS);

			if (flags & DC_EXEC) {
				present ^= trackbit;
				if (present == 0) {
					DoClearSquare(tile);
				} else {
					SetTrackBits(tile, present);
				}
			}
			break;
		}

		default: return CMD_ERROR;
	}

	if (flags & DC_EXEC) {
		MarkTileDirtyByTile(tile);
		if (crossing) {
			/* crossing is set when only TRACK_BIT_X and TRACK_BIT_Y are set. As we
			 * are removing one of these pieces, we'll need to update signals for
			 * both directions explicitly, as after the track is removed it won't
			 * 'connect' with the other piece. */
			SetSignalsOnBothDir(tile, TRACK_X);
			SetSignalsOnBothDir(tile, TRACK_Y);
		} else {
			SetSignalsOnBothDir(tile, track);
		}
	}

	return cost;
}


static const TileIndexDiffC _trackdelta[] = {
	{ -1,  0 }, {  0,  1 }, { -1,  0 }, {  0,  1 }, {  1,  0 }, {  0,  1 },
	{  0,  0 },
	{  0,  0 },
	{  1,  0 }, {  0, -1 }, {  0, -1 }, {  1,  0 }, {  0, -1 }, { -1,  0 },
	{  0,  0 },
	{  0,  0 }
};


static int32 ValidateAutoDrag(Trackdir *trackdir, TileIndex start, TileIndex end)
{
	int x = TileX(start);
	int y = TileY(start);
	int ex = TileX(end);
	int ey = TileY(end);
	int dx, dy, trdx, trdy;

	if (!ValParamTrackOrientation(*trackdir)) return CMD_ERROR;

	// calculate delta x,y from start to end tile
	dx = ex - x;
	dy = ey - y;

	// calculate delta x,y for the first direction
	trdx = _trackdelta[*trackdir].x;
	trdy = _trackdelta[*trackdir].y;

	if (!IsDiagonalTrackdir(*trackdir)) {
		trdx += _trackdelta[*trackdir ^ 1].x;
		trdy += _trackdelta[*trackdir ^ 1].y;
	}

	// validate the direction
	while (
		(trdx <= 0 && dx > 0) ||
		(trdx >= 0 && dx < 0) ||
		(trdy <= 0 && dy > 0) ||
		(trdy >= 0 && dy < 0)
	) {
		if (!HASBIT(*trackdir, 3)) { // first direction is invalid, try the other
			SETBIT(*trackdir, 3); // reverse the direction
			trdx = -trdx;
			trdy = -trdy;
		} else // other direction is invalid too, invalid drag
			return CMD_ERROR;
	}

	// (for diagonal tracks, this is already made sure of by above test), but:
	// for non-diagonal tracks, check if the start and end tile are on 1 line
	if (!IsDiagonalTrackdir(*trackdir)) {
		trdx = _trackdelta[*trackdir].x;
		trdy = _trackdelta[*trackdir].y;
		if (abs(dx) != abs(dy) && abs(dx) + abs(trdy) != abs(dy) + abs(trdx))
			return CMD_ERROR;
	}

	return 0;
}

/** Build a stretch of railroad tracks.
 * @param tile start tile of drag
 * @param p1 end tile of drag
 * @param p2 various bitstuffed elements
 * - p2 = (bit 0-3) - railroad type normal/maglev (0 = normal, 1 = mono, 2 = maglev)
 * - p2 = (bit 4-6) - track-orientation, valid values: 0-5 (Track enum)
 * - p2 = (bit 7)   - 0 = build, 1 = remove tracks
 */
static int32 CmdRailTrackHelper(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	int32 ret, total_cost = 0;
	Track track = (Track)GB(p2, 4, 3);
	Trackdir trackdir;
	byte mode = HASBIT(p2, 7);
	RailType railtype = (RailType)GB(p2, 0, 4);
	TileIndex end_tile;

	if (!ValParamRailtype(railtype) || !ValParamTrackOrientation(track)) return CMD_ERROR;
	if (p1 >= MapSize()) return CMD_ERROR;
	end_tile = p1;
	trackdir = TrackToTrackdir(track);

	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	if (CmdFailed(ValidateAutoDrag(&trackdir, tile, end_tile))) return CMD_ERROR;

	if (flags & DC_EXEC) SndPlayTileFx(SND_20_SPLAT_2, tile);

	for (;;) {
		ret = DoCommand(tile, railtype, TrackdirToTrack(trackdir), flags, (mode == 0) ? CMD_BUILD_SINGLE_RAIL : CMD_REMOVE_SINGLE_RAIL);

		if (CmdFailed(ret)) {
			if ((_error_message != STR_1007_ALREADY_BUILT) && (mode == 0)) break;
			_error_message = INVALID_STRING_ID;
		} else
			total_cost += ret;

		if (tile == end_tile) break;

		tile += ToTileIndexDiff(_trackdelta[trackdir]);

		// toggle railbit for the non-diagonal tracks
		if (!IsDiagonalTrackdir(trackdir)) trackdir ^= 1;
	}

	return (total_cost == 0) ? CMD_ERROR : total_cost;
}

/** Build rail on a stretch of track.
 * Stub for the unified rail builder/remover
 * @see CmdRailTrackHelper
 */
int32 CmdBuildRailroadTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	return CmdRailTrackHelper(tile, flags, p1, CLRBIT(p2, 7));
}

/** Build rail on a stretch of track.
 * Stub for the unified rail builder/remover
 * @see CmdRailTrackHelper
 */
int32 CmdRemoveRailroadTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	return CmdRailTrackHelper(tile, flags, p1, SETBIT(p2, 7));
}

/** Build a train depot
 * @param tile position of the train depot
 * @param p1 rail type
 * @param p2 entrance direction (DiagDirection)
 *
 * @todo When checking for the tile slope,
 * distingush between "Flat land required" and "land sloped in wrong direction"
 */
int32 CmdBuildTrainDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	Depot *d;
	int32 cost, ret;
	Slope tileh;

	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	if (!EnsureNoVehicle(tile)) return CMD_ERROR;
	/* check railtype and valid direction for depot (0 through 3), 4 in total */
	if (!ValParamRailtype(p1) || p2 > 3) return CMD_ERROR;

	tileh = GetTileSlope(tile, NULL);

	/* Prohibit construction if
		The tile is non-flat AND
		1) The AI is "old-school"
		2) build-on-slopes is disabled
		3) the tile is steep i.e. spans two height levels
		4) the exit points in the wrong direction

	*/

	if (tileh != SLOPE_FLAT && (
				_is_old_ai_player ||
				!_patches.build_on_slopes ||
				IsSteepSlope(tileh) ||
				!CanBuildDepotByTileh(p2, tileh)
			)) {
		return_cmd_error(STR_0007_FLAT_LAND_REQUIRED);
	}

	ret = DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
	if (CmdFailed(ret)) return CMD_ERROR;
	cost = ret;

	d = AllocateDepot();
	if (d == NULL) return CMD_ERROR;

	if (flags & DC_EXEC) {
		if (IsLocalPlayer()) _last_built_train_depot_tile = tile;

		MakeRailDepot(tile, _current_player, p2, p1);
		MarkTileDirtyByTile(tile);

		d->xy = tile;
		d->town_index = ClosestTownFromTile(tile, (uint)-1)->index;

		UpdateSignalsOnSegment(tile, p2);
	}

	return cost + _price.build_train_depot;
}

/** Build signals, alternate between double/single, signal/semaphore,
 * pre/exit/combo-signals, and what-else not
 * @param tile tile where to build the signals
 * @param p1 various bitstuffed elements
 * - p1 = (bit 0-2) - track-orientation, valid values: 0-5 (Track enum)
 * - p1 = (bit 3)   - choose semaphores/signals or cycle normal/pre/exit/combo depending on context
 * @param p2 used for CmdBuildManySignals() to copy direction of first signal
 * TODO: p2 should be replaced by two bits for "along" and "against" the track.
 */
int32 CmdBuildSingleSignal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	SignalVariant sigvar;
	bool pre_signal;
	Track track = (Track)(p1 & 0x7);
	int32 cost;

	// Same bit, used in different contexts
	sigvar = HASBIT(p1, 3) ? SIG_SEMAPHORE : SIG_ELECTRIC;
	pre_signal = HASBIT(p1, 3);

	if (!ValParamTrackOrientation(track) || !IsTileType(tile, MP_RAILWAY) || !EnsureNoVehicle(tile))
		return CMD_ERROR;

	/* Protect against invalid signal copying */
	if (p2 != 0 && (p2 & SignalOnTrack(track)) == 0) return CMD_ERROR;

	/* You can only build signals on plain rail tiles, and the selected track must exist */
	if (!IsPlainRailTile(tile) || !HasTrack(tile, track)) return CMD_ERROR;

	if (!CheckTileOwnership(tile)) return CMD_ERROR;

	_error_message = STR_1005_NO_SUITABLE_RAILROAD_TRACK;

	{
 		/* See if this is a valid track combination for signals, (ie, no overlap) */
 		TrackBits trackbits = GetTrackBits(tile);
		if (KILL_FIRST_BIT(trackbits) != 0 && /* More than one track present */
				trackbits != TRACK_BIT_HORZ &&
				trackbits != TRACK_BIT_VERT
		)
			return CMD_ERROR;
	}

	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	if (!HasSignalOnTrack(tile, track)) {
		// build new signals
		cost = _price.build_signals;
	} else {
		if (p2 != 0 && sigvar != GetSignalVariant(tile)) {
			// convert signals <-> semaphores
			cost = _price.build_signals + _price.remove_signals;
		} else {
			// it is free to change orientation/pre-exit-combo signals
			cost = 0;
		}
	}

	if (flags & DC_EXEC) {
		if (GetRailTileType(tile) != RAIL_TILE_SIGNALS) {
			// there are no signals at all on this tile yet
			_m[tile].m5 |= RAIL_TILE_SIGNALS; // change into signals
			_m[tile].m2 |= 0xF0;              // all signals are on
			_m[tile].m3 &= ~0xF0;          // no signals built by default
			SetSignalType(tile, SIGTYPE_NORMAL);
			SetSignalVariant(tile, sigvar);
		}

		if (p2 == 0) {
			if (!HasSignalOnTrack(tile, track)) {
				// build new signals
				_m[tile].m3 |= SignalOnTrack(track);
			} else {
				if (pre_signal) {
					// cycle between normal -> pre -> exit -> combo -> ...
					SignalType type = GetSignalType(tile);

					SetSignalType(tile, type == SIGTYPE_COMBO ? SIGTYPE_NORMAL : type + 1);
				} else {
					CycleSignalSide(tile, track);
				}
			}
		} else {
			/* If CmdBuildManySignals is called with copying signals, just copy the
			 * direction of the first signal given as parameter by CmdBuildManySignals */
			_m[tile].m3 &= ~SignalOnTrack(track);
			_m[tile].m3 |= p2 & SignalOnTrack(track);
			SetSignalVariant(tile, sigvar);
		}

		MarkTileDirtyByTile(tile);
		SetSignalsOnBothDir(tile, track);
	}

	return cost;
}

/**	Build many signals by dragging; AutoSignals
 * @param tile start tile of drag
 * @param p1  end tile of drag
 * @param p2 various bitstuffed elements
 * - p2 = (bit  0)    - 0 = build, 1 = remove signals
 * - p2 = (bit  3)    - 0 = signals, 1 = semaphores
 * - p2 = (bit  4- 6) - track-orientation, valid values: 0-5 (Track enum)
 * - p2 = (bit 24-31) - user defined signals_density
 */
static int32 CmdSignalTrackHelper(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	int32 ret, total_cost, signal_ctr;
	byte signals;
	bool error = true;
	TileIndex end_tile;

	int mode = p2 & 0x1;
	Track track = GB(p2, 4, 3);
	Trackdir trackdir = TrackToTrackdir(track);
	byte semaphores = (HASBIT(p2, 3)) ? 8 : 0;
	byte signal_density = (p2 >> 24);

	if (p1 >= MapSize()) return CMD_ERROR;
	end_tile = p1;
	if (signal_density == 0 || signal_density > 20) return CMD_ERROR;

	if (!IsTileType(tile, MP_RAILWAY)) return CMD_ERROR;

	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	/* for vertical/horizontal tracks, double the given signals density
	* since the original amount will be too dense (shorter tracks) */
	if (!IsDiagonalTrack(track))
		signal_density *= 2;

	if (CmdFailed(ValidateAutoDrag(&trackdir, tile, end_tile))) return CMD_ERROR;

	track = TrackdirToTrack(trackdir); /* trackdir might have changed, keep track in sync */

	// copy the signal-style of the first rail-piece if existing
	if (GetRailTileType(tile) == RAIL_TILE_SIGNALS && GetTrackBits(tile) != 0) { /* XXX: GetTrackBits check useless? */
		signals = _m[tile].m3 & SignalOnTrack(track);
		if (signals == 0) signals = SignalOnTrack(track); /* Can this actually occur? */

		// copy signal/semaphores style (independent of CTRL)
		semaphores = (GetSignalVariant(tile) == SIG_ELECTRIC ? 0 : 8);
	} else // no signals exist, drag a two-way signal stretch
		signals = SignalOnTrack(track);

	/* signal_ctr         - amount of tiles already processed
	 * signals_density    - patch setting to put signal on every Nth tile (double space on |, -- tracks)
	 **********
	 * trackdir   - trackdir to build with autorail
	 * semaphores - semaphores or signals
	 * signals    - is there a signal/semaphore on the first tile, copy its style (two-way/single-way)
	                and convert all others to semaphore/signal
	 * mode       - 1 remove signals, 0 build signals */
	signal_ctr = total_cost = 0;
	for (;;) {
		// only build/remove signals with the specified density
		if ((signal_ctr % signal_density) == 0 ) {
			ret = DoCommand(tile, TrackdirToTrack(trackdir) | semaphores, signals, flags, (mode == 1) ? CMD_REMOVE_SIGNALS : CMD_BUILD_SIGNALS);

			/* Abort placement for any other error than NOT_SUITABLE_TRACK
			 * This includes vehicles on track, competitor's tracks, etc. */
			if (CmdFailed(ret)) {
				if (_error_message != STR_1005_NO_SUITABLE_RAILROAD_TRACK && mode != 1) return CMD_ERROR;
				_error_message = INVALID_STRING_ID;
			} else {
				error = false;
				total_cost += ret;
			}
		}

		if (tile == end_tile) break;

		tile += ToTileIndexDiff(_trackdelta[trackdir]);
		signal_ctr++;

		// toggle railbit for the non-diagonal tracks (|, -- tracks)
		if (!IsDiagonalTrackdir(trackdir)) trackdir ^= 1;
	}

	return error ? CMD_ERROR : total_cost;
}

/** Build signals on a stretch of track.
 * Stub for the unified signal builder/remover
 * @see CmdSignalTrackHelper
 */
int32 CmdBuildSignalTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	return CmdSignalTrackHelper(tile, flags, p1, p2);
}

/** Remove signals
 * @param tile coordinates where signal is being deleted from
 * @param p1 track to remove signal from (Track enum)
 */
int32 CmdRemoveSingleSignal(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	Track track = (Track)(p1 & 0x7);

	if (!ValParamTrackOrientation(track) || !IsTileType(tile, MP_RAILWAY) || !EnsureNoVehicle(tile))
		return CMD_ERROR;

	if (!HasSignalOnTrack(tile, track)) // no signals on track?
		return CMD_ERROR;

	/* Only water can remove signals from anyone */
	if (_current_player != OWNER_WATER && !CheckTileOwnership(tile)) return CMD_ERROR;

	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	/* Do it? */
	if (flags & DC_EXEC) {
		_m[tile].m3 &= ~SignalOnTrack(track);

		/* removed last signal from tile? */
		if (GB(_m[tile].m3, 4, 4) == 0) {
			SB(_m[tile].m2, 4, 4, 0);
			SB(_m[tile].m5, 6, 2, RAIL_TILE_NORMAL >> 6); // XXX >> because the constant is meant for direct application, not use with SB
			SetSignalVariant(tile, SIG_ELECTRIC); // remove any possible semaphores
		}

		SetSignalsOnBothDir(tile, track);

		MarkTileDirtyByTile(tile);
	}

	return _price.remove_signals;
}

/** Remove signals on a stretch of track.
 * Stub for the unified signal builder/remover
 * @see CmdSignalTrackHelper
 */
int32 CmdRemoveSignalTrack(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	return CmdSignalTrackHelper(tile, flags, p1, SETBIT(p2, 0));
}

typedef int32 DoConvertRailProc(TileIndex tile, RailType totype, bool exec);

static int32 DoConvertRail(TileIndex tile, RailType totype, bool exec)
{
	if (!CheckTileOwnership(tile)) return CMD_ERROR;

	if (!EnsureNoVehicle(tile) && (!IsCompatibleRail(GetRailType(tile), totype) || IsPlainRailTile(tile))) return CMD_ERROR;

	// tile is already of requested type?
	if (GetRailType(tile) == totype) return CMD_ERROR;

	// change type.
	if (exec) {
		SetRailType(tile, totype);
		MarkTileDirtyByTile(tile);

		/* Update build vehicle window related to this depot */
		if (IsTileDepotType(tile, TRANSPORT_RAIL)) {
			Window *w = FindWindowById(WC_BUILD_VEHICLE, tile);
			if (w != NULL) {
				WP(w,buildtrain_d).railtype = totype;
				SetWindowDirty(w);
			}
		}
	}

	return _price.build_rail / 2;
}

extern int32 DoConvertStationRail(TileIndex tile, RailType totype, bool exec);
extern int32 DoConvertStreetRail(TileIndex tile, RailType totype, bool exec);
extern int32 DoConvertTunnelBridgeRail(TileIndex tile, RailType totype, bool exec);

/** Convert one rail type to the other. You can convert normal rail to
 * monorail/maglev easily or vice-versa.
 * @param tile end tile of rail conversion drag
 * @param p1 start tile of drag
 * @param p2 new railtype to convert to
 */
int32 CmdConvertRail(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
{
	int32 ret, cost, money;
	int ex;
	int ey;
	int sx, sy, x, y;

	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);

	if (!ValParamRailtype(p2)) return CMD_ERROR;
	if (p1 >= MapSize()) return CMD_ERROR;

	// make sure sx,sy are smaller than ex,ey
	ex = TileX(tile);
	ey = TileY(tile);
	sx = TileX(p1);
	sy = TileY(p1);
	if (ex < sx) intswap(ex, sx);
	if (ey < sy) intswap(ey, sy);

	money = GetAvailableMoneyForCommand();
	cost = 0;

	for (x = sx; x <= ex; ++x) {
		for (y = sy; y <= ey; ++y) {
			TileIndex tile = TileXY(x, y);
			DoConvertRailProc* proc;

			switch (GetTileType(tile)) {
				case MP_RAILWAY:      proc = DoConvertRail;             break;
				case MP_STATION:      proc = DoConvertStationRail;      break;
				case MP_STREET:       proc = DoConvertStreetRail;       break;
				case MP_TUNNELBRIDGE: proc = DoConvertTunnelBridgeRail; break;
				default: continue;
			}

			ret = proc(tile, p2, false);
			if (CmdFailed(ret)) continue;
			cost += ret;

			if (flags & DC_EXEC) {
				money -= ret;
				if (money < 0) {
					_additional_cash_required = ret;
					return cost - ret;
				}
				proc(tile, p2, true);
			}
		}
	}

	return (cost == 0) ? CMD_ERROR : cost;
}

static int32 RemoveTrainDepot(TileIndex tile, uint32 flags)
{
	if (!CheckTileOwnership(tile) && _current_player != OWNER_WATER)
		return CMD_ERROR;

	if (!EnsureNoVehicle(tile))
		return CMD_ERROR;

	if (flags & DC_EXEC) {
		DiagDirection dir = GetRailDepotDirection(tile);

		DoDeleteDepot(tile);
		UpdateSignalsOnSegment(tile, dir);
	}

	return _price.remove_train_depot;
}

static int32 ClearTile_Track(TileIndex tile, byte flags)
{
	int32 cost;
	int32 ret;
	byte m5;

	m5 = _m[tile].m5;

	if (flags & DC_AUTO) {
		if (GetRailTileType(tile) == RAIL_TILE_DEPOT_WAYPOINT) {
			return_cmd_error(STR_2004_BUILDING_MUST_BE_DEMOLISHED);
		}

		if (!IsTileOwner(tile, _current_player))
			return_cmd_error(STR_1024_AREA_IS_OWNED_BY_ANOTHER);

		return_cmd_error(STR_1008_MUST_REMOVE_RAILROAD_TRACK);
	}

	cost = 0;

	switch (GetRailTileType(tile)) {
		/* XXX: Why the fuck do we remove these thow signals first? */
		case RAIL_TILE_SIGNALS:
			if (HasSignalOnTrack(tile, TRACK_X)) {
				ret = DoCommand(tile, TRACK_X, 0, flags, CMD_REMOVE_SIGNALS);
				if (CmdFailed(ret)) return CMD_ERROR;
				cost += ret;
			}
			if (HasSignalOnTrack(tile, TRACK_LOWER)) {
				ret = DoCommand(tile, TRACK_LOWER, 0, flags, CMD_REMOVE_SIGNALS);
				if (CmdFailed(ret)) return CMD_ERROR;
				cost += ret;
			}

			m5 &= TRACK_BIT_MASK;
			if (!(flags & DC_EXEC)) {
				for (; m5 != 0; m5 >>= 1) if (m5 & 1) cost += _price.remove_rail;
				return cost;
			}
			/* FALLTHROUGH */

		case RAIL_TILE_NORMAL: {
			uint i;

			for (i = 0; m5 != 0; i++, m5 >>= 1) {
				if (m5 & 1) {
					ret = DoCommand(tile, 0, i, flags, CMD_REMOVE_SINGLE_RAIL);
					if (CmdFailed(ret)) return CMD_ERROR;
					cost += ret;
				}
			}
			return cost;
		}

		case RAIL_TILE_DEPOT_WAYPOINT:
			if (GetRailTileSubtype(tile) == RAIL_SUBTYPE_DEPOT) {
				return RemoveTrainDepot(tile, flags);
			} else {
				return RemoveTrainWaypoint(tile, flags, false);
			}

		default:
			return CMD_ERROR;
	}
}

#include "table/track_land.h"

static void DrawSingleSignal(TileIndex tile, byte condition, uint image, uint pos)
{
	bool side = _opt.road_side & _patches.signal_side;
	static const Point SignalPositions[2][12] = {
		{      /* Signals on the left side */
		/*  LEFT      LEFT      RIGHT     RIGHT     UPPER     UPPER */
			{ 8,  5}, {14,  1}, { 1, 14}, { 9, 11}, { 1,  0}, { 3, 10},
		/*  LOWER     LOWER     X         X         Y         Y     */
			{11,  4}, {14, 14}, {11,  3}, { 4, 13}, { 3,  4}, {11, 13}
		}, {   /* Signals on the right side */
		/*  LEFT      LEFT      RIGHT     RIGHT     UPPER     UPPER */
			{14,  1}, {12, 10}, { 4,  6}, { 1, 14}, {10,  4}, { 0,  1},
		/*  LOWER     LOWER     X         X         Y         Y     */
			{14, 14}, { 5, 12}, {11, 13}, { 4,  3}, {13,  4}, { 3, 11}
		}
	};

	static const SpriteID SignalBase[2][2][4] = {
		{    /* Signals on left side */
			{  0x4FB, 0x1323, 0x1333, 0x1343}, /* light signals */
			{ 0x1353, 0x1363, 0x1373, 0x1383}  /* semaphores    */
		}, { /* Signals on right side */
			{  0x4FB, 0x1323, 0x1333, 0x1343}, /* light signals */
			{ 0x1446, 0x1456, 0x1466, 0x1476}  /* semaphores    */
		/*         |       |       |       |     */
		/*    normal,  entry,   exit,  combo     */
		}
	};

	uint x = TileX(tile) * TILE_SIZE + SignalPositions[side][pos].x;
	uint y = TileY(tile) * TILE_SIZE + SignalPositions[side][pos].y;

	SpriteID sprite;

	/* _signal_base is set by our NewGRF Action 5 loader. If it is 0 then we
	 * just draw the standard signals, else we get the offset from _signal_base
	 * and draw that sprite. All the signal sprites are loaded sequentially. */
	if (_signal_base == 0 || (GetSignalType(tile) == 0 && GetSignalVariant(tile) == SIG_ELECTRIC)) {
		sprite = SignalBase[side][GetSignalVariant(tile)][GetSignalType(tile)] + image + condition;
	} else {
		sprite = _signal_base + (GetSignalType(tile) - 1) * 16 + GetSignalVariant(tile) * 64 + image + condition;
	}

	AddSortableSpriteToDraw(sprite, x, y, 1, 1, 10, GetSlopeZ(x,y));
}

static uint32 _drawtile_track_palette;


static void DrawTrackFence_NW(const TileInfo *ti)
{
	uint32 image = 0x515;
	if (ti->tileh != SLOPE_FLAT) image = (ti->tileh & SLOPE_S) ? 0x519 : 0x51B;
	AddSortableSpriteToDraw(image | _drawtile_track_palette,
		ti->x, ti->y + 1, 16, 1, 4, ti->z);
}

static void DrawTrackFence_SE(const TileInfo *ti)
{
	uint32 image = 0x515;
	if (ti->tileh != SLOPE_FLAT) image = (ti->tileh & SLOPE_S) ? 0x519 : 0x51B;
	AddSortableSpriteToDraw(image | _drawtile_track_palette,
		ti->x, ti->y + TILE_SIZE - 1, 16, 1, 4, ti->z);
}

static void DrawTrackFence_NW_SE(const TileInfo *ti)
{
	DrawTrackFence_NW(ti);
	DrawTrackFence_SE(ti);
}

static void DrawTrackFence_NE(const TileInfo *ti)
{
	uint32 image = 0x516;
	if (ti->tileh != SLOPE_FLAT) image = (ti->tileh & SLOPE_S) ? 0x51A : 0x51C;
	AddSortableSpriteToDraw(image | _drawtile_track_palette,
		ti->x + 1, ti->y, 1, 16, 4, ti->z);
}

static void DrawTrackFence_SW(const TileInfo *ti)
{
	uint32 image = 0x516;
	if (ti->tileh != SLOPE_FLAT) image = (ti->tileh & SLOPE_S) ? 0x51A : 0x51C;
	AddSortableSpriteToDraw(image | _drawtile_track_palette,
		ti->x + TILE_SIZE - 1, ti->y, 1, 16, 4, ti->z);
}

static void DrawTrackFence_NE_SW(const TileInfo *ti)
{
	DrawTrackFence_NE(ti);
	DrawTrackFence_SW(ti);
}

static void DrawTrackFence_NS_1(const TileInfo *ti)
{
	int z = ti->z;
	if (ti->tileh & SLOPE_W) z += TILE_HEIGHT;
	AddSortableSpriteToDraw(0x517 | _drawtile_track_palette,
		ti->x + TILE_SIZE / 2, ti->y + TILE_SIZE / 2, 1, 1, 4, z);
}

static void DrawTrackFence_NS_2(const TileInfo *ti)
{
	int z = ti->z;
	if (ti->tileh & SLOPE_E) z += TILE_HEIGHT;
	AddSortableSpriteToDraw(0x517 | _drawtile_track_palette,
		ti->x + TILE_SIZE / 2, ti->y + TILE_SIZE / 2, 1, 1, 4, z);
}

static void DrawTrackFence_WE_1(const TileInfo *ti)
{
	int z = ti->z;
	if (ti->tileh & SLOPE_N) z += TILE_HEIGHT;
	AddSortableSpriteToDraw(0x518 | _drawtile_track_palette,
		ti->x + TILE_SIZE / 2, ti->y + TILE_SIZE / 2, 1, 1, 4, z);
}

static void DrawTrackFence_WE_2(const TileInfo *ti)
{
	int z = ti->z;
	if (ti->tileh & SLOPE_S) z += TILE_HEIGHT;
	AddSortableSpriteToDraw(0x518 | _drawtile_track_palette,
		ti->x + TILE_SIZE / 2, ti->y + TILE_SIZE / 2, 1, 1, 4, z);
}

static void DetTrackDrawProc_Null(const TileInfo *ti)
{
	/* nothing should be here */
}

typedef void DetailedTrackProc(const TileInfo *ti);
static DetailedTrackProc* const _detailed_track_proc[] = {
	DetTrackDrawProc_Null,
	DetTrackDrawProc_Null,

	DrawTrackFence_NW,
	DrawTrackFence_SE,
	DrawTrackFence_NW_SE,

	DrawTrackFence_NE,
	DrawTrackFence_SW,
	DrawTrackFence_NE_SW,

	DrawTrackFence_NS_1,
	DrawTrackFence_NS_2,

	DrawTrackFence_WE_1,
	DrawTrackFence_WE_2,

	DetTrackDrawProc_Null,
	DetTrackDrawProc_Null,
	DetTrackDrawProc_Null,
	DetTrackDrawProc_Null,
};

static void DrawSpecialBuilding(
	uint32 image, uint32 offset,
	const TileInfo* ti,
	byte x, byte y, byte z,
	byte xsize, byte ysize, byte zsize)
{
	if (image & PALETTE_MODIFIER_COLOR) image |= _drawtile_track_palette;
	image += offset;
	if (_display_opt & DO_TRANS_BUILDINGS) MAKE_TRANSPARENT(image);
	AddSortableSpriteToDraw(image, ti->x + x, ti->y + y, xsize, ysize, zsize, ti->z + z);
}

/**
 * Draw ground sprite and track bits
 * @param ti TileInfo
 * @param track TrackBits to draw
 * @param earth Draw as earth
 * @param snow Draw as snow
 * @param flat Always draw foundation
 */
static void DrawTrackBits(TileInfo* ti, TrackBits track, bool flat)
{
	const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));
	PalSpriteID image;
	bool junction = false;
	bool earth = IsBarrenRailGround(ti->tile);
	bool snow = IsSnowRailGround(ti->tile);

	// Select the sprite to use.
	(image = rti->base_sprites.track_y, track == TRACK_BIT_Y) ||
	(image++,                           track == TRACK_BIT_X) ||
	(image++,                           track == TRACK_BIT_UPPER) ||
	(image++,                           track == TRACK_BIT_LOWER) ||
	(image++,                           track == TRACK_BIT_RIGHT) ||
	(image++,                           track == TRACK_BIT_LEFT) ||
	(image++,                           track == TRACK_BIT_CROSS) ||

	(image = rti->base_sprites.track_ns, track == TRACK_BIT_HORZ) ||
	(image++,                            track == TRACK_BIT_VERT) ||

	(junction = true, false) ||
	(image = rti->base_sprites.ground, (track & TRACK_BIT_3WAY_NE) == 0) ||
	(image++,                          (track & TRACK_BIT_3WAY_SW) == 0) ||
	(image++,                          (track & TRACK_BIT_3WAY_NW) == 0) ||
	(image++,                          (track & TRACK_BIT_3WAY_SE) == 0) ||
	(image++, true);

	if (ti->tileh != SLOPE_FLAT) {
		int foundation;

		if (flat) {
			foundation = ti->tileh;
		} else {
			foundation = GetRailFoundation(ti->tileh, track);
		}

		if (foundation != 0)
			DrawFoundation(ti, foundation);

		// DrawFoundation() modifies ti.
		// Default sloped sprites..
		if (ti->tileh != SLOPE_FLAT)
			image = _track_sloped_sprites[ti->tileh - 1] + rti->base_sprites.track_y;
	}

	if (earth) {
		image = (image & SPRITE_MASK) | PALETTE_TO_BARE_LAND; // Use brown palette
	} else if (snow) {
		image += rti->snow_offset;
	}

	DrawGroundSprite(image);

	// Draw track pieces individually for junction tiles
	if (junction) {
		if (track & TRACK_BIT_X)     DrawGroundSprite(rti->base_sprites.single_y);
		if (track & TRACK_BIT_Y)     DrawGroundSprite(rti->base_sprites.single_x);
		if (track & TRACK_BIT_UPPER) DrawGroundSprite(rti->base_sprites.single_n);
		if (track & TRACK_BIT_LOWER) DrawGroundSprite(rti->base_sprites.single_s);
		if (track & TRACK_BIT_LEFT)  DrawGroundSprite(rti->base_sprites.single_w);
		if (track & TRACK_BIT_RIGHT) DrawGroundSprite(rti->base_sprites.single_e);
	}

	if (GetRailType(ti->tile) == RAILTYPE_ELECTRIC) DrawCatenary(ti);

}

static void DrawSignals(TileIndex tile, TrackBits rails)
{
#define MAYBE_DRAW_SIGNAL(x,y,z) if (IsSignalPresent(tile, x)) DrawSingleSignal(tile, GetSingleSignalState(tile, x), y - 0x4FB, z)

	if (!(rails & TRACK_BIT_Y)) {
		if (!(rails & TRACK_BIT_X)) {
			if (rails & TRACK_BIT_LEFT) {
				MAYBE_DRAW_SIGNAL(2, 0x509, 0);
				MAYBE_DRAW_SIGNAL(3, 0x507, 1);
			}
			if (rails & TRACK_BIT_RIGHT) {
				MAYBE_DRAW_SIGNAL(0, 0x509, 2);
				MAYBE_DRAW_SIGNAL(1, 0x507, 3);
			}
			if (rails & TRACK_BIT_UPPER) {
				MAYBE_DRAW_SIGNAL(3, 0x505, 4);
				MAYBE_DRAW_SIGNAL(2, 0x503, 5);
			}
			if (rails & TRACK_BIT_LOWER) {
				MAYBE_DRAW_SIGNAL(1, 0x505, 6);
				MAYBE_DRAW_SIGNAL(0, 0x503, 7);
			}
		} else {
			MAYBE_DRAW_SIGNAL(3, 0x4FB, 8);
			MAYBE_DRAW_SIGNAL(2, 0x4FD, 9);
		}
	} else {
		MAYBE_DRAW_SIGNAL(3, 0x4FF, 10);
		MAYBE_DRAW_SIGNAL(2, 0x501, 11);
	}
}

static void DrawTile_Track(TileInfo *ti)
{
	const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));
	PalSpriteID image;

	_drawtile_track_palette = SPRITE_PALETTE(PLAYER_SPRITE_COLOR(GetTileOwner(ti->tile)));

	if (GetRailTileType(ti->tile) != RAIL_TILE_DEPOT_WAYPOINT) {
		TrackBits rails = GetTrackBits(ti->tile);

		DrawTrackBits(ti, rails, false);

		if (_display_opt & DO_FULL_DETAIL) _detailed_track_proc[GetRailGroundType(ti->tile)](ti);

		/* draw signals also? */
		if (GetRailTileType(ti->tile) == RAIL_TILE_SIGNALS) DrawSignals(ti->tile, rails);

	} else {
		/* draw depots / waypoints */
		const DrawTrackSeqStruct *drss;
		bool is_depot = GetRailTileSubtype(ti->tile) == RAIL_SUBTYPE_DEPOT;

		if (ti->tileh != SLOPE_FLAT) DrawFoundation(ti, ti->tileh);

		if (IsRailWaypoint(ti->tile) && IsCustomWaypoint(ti->tile)) {
			// look for customization
			byte stat_id = GetWaypointByTile(ti->tile)->stat_id;
			const StationSpec *statspec = GetCustomStationSpec(STAT_CLASS_WAYP, stat_id);

			if (statspec != NULL) {
				DrawTileSeqStruct const *seq;
				// emulate station tile - open with building
				uint tile = 2;
				const DrawTileSprites *cust;
				Station *st = ComposeWaypointStation(ti->tile);

				uint32 relocation = GetCustomStationRelocation(statspec, st, ti->tile);

				if (HASBIT(statspec->callbackmask, CBM_CUSTOM_LAYOUT)) {
					uint16 callback = GetStationCallback(CBID_STATION_SPRITE_LAYOUT, 0, 0, statspec, st, ti->tile);
					if (callback != CALLBACK_FAILED) tile = callback;
				}

				if (statspec->renderdata == NULL) {
					cust = GetStationTileLayout(tile);
				} else {
					cust = &statspec->renderdata[(tile < statspec->tiles ? tile : 0) + GetWaypointAxis(ti->tile)];
				}

				/* If there is no sprite layout, we fall back to the default waypoint graphics. */
				if (cust != NULL && cust->seq != NULL) {
					image = cust->ground_sprite;
					if (HASBIT(image, 31)) {
						CLRBIT(image, 31);
						image += GetCustomStationGroundRelocation(statspec, st, ti->tile);
						image += rti->custom_ground_offset;
					} else {
						image += rti->total_offset;
					}

					DrawGroundSprite(image);

					if (GetRailType(ti->tile) == RAILTYPE_ELECTRIC) DrawCatenary(ti);

					foreach_draw_tile_seq(seq, cust->seq) {
						DrawSpecialBuilding(
							seq->image + relocation, 0, ti,
							seq->delta_x, seq->delta_y, seq->delta_z,
							seq->width, seq->height, seq->unk
						);
					}
					return;
				}
			}
		}

		drss = is_depot ? _track_depot_layout_table[GetRailDepotDirection(ti->tile)] : _track_waypoint_layout_table[GetWaypointAxis(ti->tile)];

		image = drss++->image;
		/* @note This is kind of an ugly hack, as the PALETTE_MODIFIER_COLOR indicates
		 * whether the sprite is railtype dependent. Rewrite this asap */
		if (image & PALETTE_MODIFIER_COLOR) image = (image & SPRITE_MASK) + rti->total_offset;

		// adjust ground tile for desert
		// (don't adjust for arctic depots, because snow in depots looks weird)
		// type >= 4 means waypoints
		if (IsSnowRailGround(ti->tile) && (_opt.landscape == LT_DESERT || !is_depot)) {
			if (image != SPR_FLAT_GRASS_TILE) {
				image += rti->snow_offset; // tile with tracks
			} else {
				image = SPR_FLAT_SNOWY_TILE; // flat ground
			}
		}

		DrawGroundSprite(image);

		if (GetRailType(ti->tile) == RAILTYPE_ELECTRIC) DrawCatenary(ti);

		for (; drss->image != 0; drss++) {
			DrawSpecialBuilding(
				drss->image, is_depot ? rti->total_offset : 0, ti,
				drss->subcoord_x, drss->subcoord_y, 0,
				drss->width, drss->height, 0x17
			);
		}
	}
}

void DrawTrainDepotSprite(int x, int y, int image, RailType railtype)
{
	uint32 ormod, img;
	const RailtypeInfo *rti = GetRailTypeInfo(railtype);
	const DrawTrackSeqStruct *dtss;

	ormod = PLAYER_SPRITE_COLOR(_local_player);

	dtss = _track_depot_layout_table[image];

	x += 33;
	y += 17;

	img = dtss++->image;
	/* @note This is kind of an ugly hack, as the PALETTE_MODIFIER_COLOR indicates
	 * whether the sprite is railtype dependent. Rewrite this asap */
	if (img & PALETTE_MODIFIER_COLOR) img = (img & SPRITE_MASK) + rti->total_offset;
	DrawSprite(img, x, y);

	for (; dtss->image != 0; dtss++) {
		Point pt = RemapCoords(dtss->subcoord_x, dtss->subcoord_y, 0);
		image = dtss->image;
		if (image & PALETTE_MODIFIER_COLOR) image |= ormod;
		DrawSprite(image + rti->total_offset, x + pt.x, y + pt.y);
	}
}

void DrawDefaultWaypointSprite(int x, int y, RailType railtype)
{
	const DrawTrackSeqStruct *dtss = _track_waypoint_layout_table[0];
	const RailtypeInfo *rti = GetRailTypeInfo(railtype);
	uint32 img;

	img = dtss++->image;
	if (img & PALETTE_MODIFIER_COLOR) img = (img & SPRITE_MASK) + rti->total_offset;
	DrawSprite(img, x, y);

	for (; dtss->image != 0; dtss++) {
		Point pt = RemapCoords(dtss->subcoord_x, dtss->subcoord_y, 0);
		img = dtss->image;
		if (img & PALETTE_MODIFIER_COLOR) img |= PLAYER_SPRITE_COLOR(_local_player);
		DrawSprite(img, x + pt.x, y + pt.y);
	}
}

typedef struct SetSignalsData {
	int cur;
	int cur_stack;
	bool stop;
	bool has_presignal;

	// presignal info
	int presignal_exits;
	int presignal_exits_free;

	// these are used to keep track of the signals that change.
	byte bit[NUM_SSD_ENTRY];
	TileIndex tile[NUM_SSD_ENTRY];

	// these are used to keep track of the stack that modifies presignals recursively
	TileIndex next_tile[NUM_SSD_STACK];
	byte next_dir[NUM_SSD_STACK];

} SetSignalsData;

static bool SetSignalsEnumProc(TileIndex tile, SetSignalsData *ssd, int track, uint length, byte *state)
{
	if (!IsTileType(tile, MP_RAILWAY)) return false;

	// the tile has signals?
	if (HasSignalOnTrack(tile, TrackdirToTrack(track))) {
		if (HasSignalOnTrackdir(tile, ReverseTrackdir(track))) {
			// yes, add the signal to the list of signals
			if (ssd->cur != NUM_SSD_ENTRY) {
				ssd->tile[ssd->cur] = tile; // remember the tile index
				ssd->bit[ssd->cur] = track; // and the controlling bit number
				ssd->cur++;
			}

			// remember if this block has a presignal.
			ssd->has_presignal |= IsPresignalEntry(tile);
		}

		if (HasSignalOnTrackdir(tile, track) && IsPresignalExit(tile)) {
			// this is an exit signal that points out from the segment
			ssd->presignal_exits++;
			if (GetSignalStateByTrackdir(tile, track) != SIGNAL_STATE_RED)
				ssd->presignal_exits_free++;
		}

		return true;
	} else if (IsTileDepotType(tile, TRANSPORT_RAIL)) {
		return true; // don't look further if the tile is a depot
	}

	return false;
}

/* Struct to parse data from VehicleFromPos to SignalVehicleCheckProc */
typedef struct SignalVehicleCheckStruct {
	TileIndex tile;
	uint track;
} SignalVehicleCheckStruct;

static void *SignalVehicleCheckProc(Vehicle *v, void *data)
{
	const SignalVehicleCheckStruct* dest = data;
	TileIndex tile;

	if (v->type != VEH_Train) return NULL;

	/* Find the tile outside the tunnel, for signalling */
	if (v->u.rail.track == 0x40) {
		tile = GetVehicleOutOfTunnelTile(v);
	} else {
		tile = v->tile;
	}

	/* Wrong tile, or no train? Not a match */
	if (tile != dest->tile) return NULL;

	/* Are we on the same piece of track? */
	if (dest->track & (v->u.rail.track + (v->u.rail.track << 8))) return v;

	return NULL;
}

/* Special check for SetSignalsAfterProc, to see if there is a vehicle on this tile */
static bool SignalVehicleCheck(TileIndex tile, uint track)
{
	SignalVehicleCheckStruct dest;

	dest.tile = tile;
	dest.track = track;

	/** @todo "Hackish" fix for the tunnel problems. This is needed because a tunnel
	 * is some kind of invisible black hole, and there is some special magic going
	 * on in there. This 'workaround' can be removed once the maprewrite is done.
	 */
	if (IsTunnelTile(tile)) {
		// It is a tunnel we're checking, we need to do some special stuff
		// because VehicleFromPos will not find the vihicle otherwise
		TileIndex end = GetOtherTunnelEnd(tile);
		DiagDirection direction = GetTunnelDirection(tile);

		dest.track = 1 << (direction & 1); // get the trackbit the vehicle would have if it has not entered the tunnel yet (ie is still visible)

		// check for a vehicle with that trackdir on the start tile of the tunnel
		if (VehicleFromPos(tile, &dest, SignalVehicleCheckProc) != NULL) return true;

		// check for a vehicle with that trackdir on the end tile of the tunnel
		if (VehicleFromPos(end, &dest, SignalVehicleCheckProc) != NULL) return true;

		// now check all tiles from start to end for a "hidden" vehicle
		// NOTE: the hashes for tiles may overlap, so this could maybe be optimised a bit by not checking every tile?
		dest.track = 0x40; // trackbit for vehicles "hidden" inside a tunnel
		for (; tile != end; tile += TileOffsByDir(direction)) {
			if (VehicleFromPos(tile, &dest, SignalVehicleCheckProc) != NULL)
				return true;
		}

		// no vehicle found
		return false;
	}

	return VehicleFromPos(tile, &dest, SignalVehicleCheckProc) != NULL;
}

static void SetSignalsAfterProc(TrackPathFinder *tpf)
{
	SetSignalsData *ssd = tpf->userdata;
	const TrackPathFinderLink* link;
	uint offs;
	uint i;

	ssd->stop = false;

	/* Go through all the PF tiles */
	for (i = 0; i < lengthof(tpf->hash_head); i++) {
		/* Empty hash item */
		if (tpf->hash_head[i] == 0) continue;

		/* If 0x8000 is not set, there is only 1 item */
		if (!(tpf->hash_head[i] & 0x8000)) {
			/* Check if there is a vehicle on this tile */
			if (SignalVehicleCheck(tpf->hash_tile[i], tpf->hash_head[i])) {
				ssd->stop = true;
				return;
			}
		} else {
			/* There are multiple items, where hash_tile points to the first item in the list */
			offs = tpf->hash_tile[i];
			do {
				/* Find the next item */
				link = PATHFIND_GET_LINK_PTR(tpf, offs);
				/* Check if there is a vehicle on this tile */
				if (SignalVehicleCheck(link->tile, link->flags)) {
					ssd->stop = true;
					return;
				}
				/* Goto the next item */
			} while ((offs = link->next) != 0xFFFF);
		}
	}
}

static const byte _dir_from_track[14] = {
	0,1,0,1,2,1, 0,0,
	2,3,3,2,3,0,
};


static void ChangeSignalStates(SetSignalsData *ssd)
{
	int i;

	// thinking about presignals...
	// the presignal is green if,
	//   if no train is in the segment AND
	//   there is at least one green exit signal OR
	//   there are no exit signals in the segment

	// then mark the signals in the segment accordingly
	for (i = 0; i != ssd->cur; i++) {
		TileIndex tile = ssd->tile[i];
		byte bit = SignalAgainstTrackdir(ssd->bit[i]);
		uint16 m2 = _m[tile].m2;

		// presignals don't turn green if there is at least one presignal exit and none are free
		if (IsPresignalEntry(tile)) {
			int ex = ssd->presignal_exits, exfree = ssd->presignal_exits_free;

			// subtract for dual combo signals so they don't count themselves
			if (IsPresignalExit(tile) && HasSignalOnTrackdir(tile, ssd->bit[i])) {
				ex--;
				if (GetSignalStateByTrackdir(tile, ssd->bit[i]) != SIGNAL_STATE_RED) exfree--;
			}

			// if we have exits and none are free, make red.
			if (ex && !exfree) goto make_red;
		}

		// check if the signal is unaffected.
		if (ssd->stop) {
make_red:
			// turn red
			if ((bit & m2) == 0) continue;
		} else {
			// turn green
			if ((bit & m2) != 0) continue;
		}

		/* Update signals on the other side of this exit-combo signal; it changed. */
		if (IsPresignalExit(tile)) {
			if (ssd->cur_stack != NUM_SSD_STACK) {
				ssd->next_tile[ssd->cur_stack] = tile;
				ssd->next_dir[ssd->cur_stack] = _dir_from_track[ssd->bit[i]];
				ssd->cur_stack++;
			} else {
				printf("NUM_SSD_STACK too small\n"); /// @todo WTF is this???
			}
		}

		// it changed, so toggle it
		_m[tile].m2 = m2 ^ bit;
		MarkTileDirtyByTile(tile);
	}
}


bool UpdateSignalsOnSegment(TileIndex tile, DiagDirection direction)
{
	SetSignalsData ssd;
	int result = -1;

	ssd.cur_stack = 0;

	for (;;) {
		// go through one segment and update all signals pointing into that segment.
		ssd.cur = ssd.presignal_exits = ssd.presignal_exits_free = 0;
		ssd.has_presignal = false;

		FollowTrack(tile, 0xC000 | TRANSPORT_RAIL, direction, (TPFEnumProc*)SetSignalsEnumProc, SetSignalsAfterProc, &ssd);
		ChangeSignalStates(&ssd);

		// remember the result only for the first iteration.
		if (result < 0) result = ssd.stop;

		// if any exit signals were changed, we need to keep going to modify the stuff behind those.
		if (ssd.cur_stack == 0) break;

		// one or more exit signals were changed, so we need to update another segment too.
		tile = ssd.next_tile[--ssd.cur_stack];
		direction = ssd.next_dir[ssd.cur_stack];
	}

	return result != 0;
}

void SetSignalsOnBothDir(TileIndex tile, byte track)
{
	static const DiagDirection _search_dir_1[] = {
		DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_SW, DIAGDIR_SE
	};
	static const DiagDirection _search_dir_2[] = {
		DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_NW, DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_NE
	};

	UpdateSignalsOnSegment(tile, _search_dir_1[track]);
	UpdateSignalsOnSegment(tile, _search_dir_2[track]);
}

static uint GetSlopeZ_Track(const TileInfo* ti)
{
	Slope tileh = ti->tileh;
	uint z = ti->z;

	if (tileh == SLOPE_FLAT) return z;
	if (GetRailTileType(ti->tile) == RAIL_TILE_DEPOT_WAYPOINT) {
		return z + TILE_HEIGHT;
	} else {
		uint f = GetRailFoundation(ti->tileh, GetTrackBits(ti->tile));

		if (f != 0) {
			if (f < 15) return z + TILE_HEIGHT; // leveled foundation
			tileh = _inclined_tileh[f - 15]; // inclined foundation
		}
		return z + GetPartialZ(ti->x & 0xF, ti->y & 0xF, tileh);
	}
}

static Slope GetSlopeTileh_Track(TileIndex tile, Slope tileh)
{
	if (tileh == SLOPE_FLAT) return SLOPE_FLAT;
	if (GetRailTileType(tile) == RAIL_TILE_DEPOT_WAYPOINT) {
		return SLOPE_FLAT;
	} else {
		uint f = GetRailFoundation(tileh, GetTrackBits(tile));

		if (f == 0) return tileh;
		if (f < 15) return SLOPE_FLAT; // leveled foundation
		return _inclined_tileh[f - 15]; // inclined foundation
	}
}

static void GetAcceptedCargo_Track(TileIndex tile, AcceptedCargo ac)
{
	/* not used */
}

static void AnimateTile_Track(TileIndex tile)
{
	/* not used */
}

static void TileLoop_Track(TileIndex tile)
{
	RailGroundType old_ground = GetRailGroundType(tile);
	RailGroundType new_ground = old_ground;
	bool quick_return = false;

	switch (_opt.landscape) {
		case LT_HILLY:
			if (GetTileZ(tile) > _opt.snow_line) {
				new_ground = RAIL_GROUND_ICE_DESERT;
				quick_return = true;
			}
			break;

		case LT_DESERT:
			if (GetTropicZone(tile) == TROPICZONE_DESERT) {
				new_ground = RAIL_GROUND_ICE_DESERT;
				quick_return = true;
			}
			break;
	}

	if (new_ground != old_ground) {
		SetRailGroundType(tile, new_ground);
		MarkTileDirtyByTile(tile);
	}

	if (quick_return) return;

	// Don't continue tile loop for depots
	if (GetRailTileType(tile) == RAIL_TILE_DEPOT_WAYPOINT) return;

	new_ground = RAIL_GROUND_GRASS;

	if (old_ground != RAIL_GROUND_BARREN) { /* wait until bottom is green */
		/* determine direction of fence */
		TrackBits rail = GetTrackBits(tile);

		switch (rail) {
			case TRACK_BIT_UPPER: new_ground = RAIL_GROUND_FENCE_HORIZ1; break;
			case TRACK_BIT_LOWER: new_ground = RAIL_GROUND_FENCE_HORIZ2; break;
			case TRACK_BIT_LEFT:  new_ground = RAIL_GROUND_FENCE_VERT1;  break;
			case TRACK_BIT_RIGHT: new_ground = RAIL_GROUND_FENCE_VERT2;  break;

			default: {
				PlayerID owner = GetTileOwner(tile);

				if (rail == (TRACK_BIT_LOWER | TRACK_BIT_RIGHT) || (
							(rail & TRACK_BIT_3WAY_NW) == 0 &&
							(rail & TRACK_BIT_X)
						)) {
					TileIndex n = tile + TileDiffXY(0, -1);
					TrackBits nrail = GetTrackBits(n);

					if (!IsTileType(n, MP_RAILWAY) ||
							!IsTileOwner(n, owner) ||
							nrail == TRACK_BIT_UPPER ||
							nrail == TRACK_BIT_LEFT) {
						new_ground = RAIL_GROUND_FENCE_NW;
					}
				}

				if (rail == (TRACK_BIT_UPPER | TRACK_BIT_LEFT) || (
							(rail & TRACK_BIT_3WAY_SE) == 0 &&
							(rail & TRACK_BIT_X)
						)) {
					TileIndex n = tile + TileDiffXY(0, 1);
					TrackBits nrail = GetTrackBits(n);

					if (!IsTileType(n, MP_RAILWAY) ||
							!IsTileOwner(n, owner) ||
							nrail == TRACK_BIT_LOWER ||
							nrail == TRACK_BIT_RIGHT) {
						new_ground = (new_ground == RAIL_GROUND_FENCE_NW) ?
							RAIL_GROUND_FENCE_SENW : RAIL_GROUND_FENCE_SE;
					}
				}

				if (rail == (TRACK_BIT_LOWER | TRACK_BIT_LEFT) || (
							(rail & TRACK_BIT_3WAY_NE) == 0 &&
							(rail & TRACK_BIT_Y)
						)) {
					TileIndex n = tile + TileDiffXY(-1, 0);
					TrackBits nrail = GetTrackBits(n);

					if (!IsTileType(n, MP_RAILWAY) ||
							!IsTileOwner(n, owner) ||
							nrail == TRACK_BIT_UPPER ||
							nrail == TRACK_BIT_RIGHT) {
						new_ground = RAIL_GROUND_FENCE_NE;
					}
				}

				if (rail == (TRACK_BIT_UPPER | TRACK_BIT_RIGHT) || (
							(rail & TRACK_BIT_3WAY_SW) == 0 &&
							(rail & TRACK_BIT_Y)
						)) {
					TileIndex n = tile + TileDiffXY(1, 0);
					TrackBits nrail = GetTrackBits(n);

					if (!IsTileType(n, MP_RAILWAY) ||
							!IsTileOwner(n, owner) ||
							nrail == TRACK_BIT_LOWER ||
							nrail == TRACK_BIT_LEFT) {
						new_ground = (new_ground == RAIL_GROUND_FENCE_NE) ?
							RAIL_GROUND_FENCE_NESW : RAIL_GROUND_FENCE_SW;
					}
				}
				break;
			}
		}
	}

	if (old_ground != new_ground) {
		SetRailGroundType(tile, new_ground);
		MarkTileDirtyByTile(tile);
	}
}


static uint32 GetTileTrackStatus_Track(TileIndex tile, TransportType mode)
{
	byte a;
	uint16 b;

	if (mode != TRANSPORT_RAIL) return 0;

	if (GetRailTileType(tile) != RAIL_TILE_DEPOT_WAYPOINT) {
		TrackBits rails = GetTrackBits(tile);
		uint32 ret = rails * 0x101;

		if (GetRailTileType(tile) != RAIL_TILE_SIGNALS) {
			if (rails == TRACK_BIT_CROSS) ret |= 0x40;
		} else {
			/* has_signals */

			a = _m[tile].m3;
			b = _m[tile].m2;

			b &= a;

			/* When signals are not present (in neither
			 * direction), we pretend them to be green. (So if
			 * signals are only one way, the other way will
			 * implicitely become `red' */
			if ((a & 0xC0) == 0) b |= 0xC0;
			if ((a & 0x30) == 0) b |= 0x30;

			if ((b & 0x80) == 0) ret |= 0x10070000;
			if ((b & 0x40) == 0) ret |= 0x07100000;
			if ((b & 0x20) == 0) ret |= 0x20080000;
			if ((b & 0x10) == 0) ret |= 0x08200000;
		}
		return ret;
	} else {
		if (GetRailTileSubtype(tile) == RAIL_SUBTYPE_DEPOT) {
			return (DiagDirToAxis(GetRailDepotDirection(tile)) == AXIS_X ? TRACK_BIT_X : TRACK_BIT_Y) * 0x101;
		} else {
			return GetRailWaypointBits(tile) * 0x101;
		}
	}
}

static void ClickTile_Track(TileIndex tile)
{
	if (IsTileDepotType(tile, TRANSPORT_RAIL)) {
		ShowTrainDepotWindow(tile);
	} else if (IsRailWaypoint(tile)) {
		ShowRenameWaypointWindow(GetWaypointByTile(tile));
	}
}

static void GetTileDesc_Track(TileIndex tile, TileDesc *td)
{
	td->owner = GetTileOwner(tile);
	switch (GetRailTileType(tile)) {
		case RAIL_TILE_NORMAL:
			td->str = STR_1021_RAILROAD_TRACK;
			break;

		case RAIL_TILE_SIGNALS: {
			const StringID signal_type[] = {
				STR_RAILROAD_TRACK_WITH_NORMAL_SIGNALS,
				STR_RAILROAD_TRACK_WITH_PRESIGNALS,
				STR_RAILROAD_TRACK_WITH_EXITSIGNALS,
				STR_RAILROAD_TRACK_WITH_COMBOSIGNALS
			};

			td->str = signal_type[GetSignalType(tile)];
			break;
		}

		case RAIL_TILE_DEPOT_WAYPOINT:
		default:
			td->str = (GetRailTileSubtype(tile) == RAIL_SUBTYPE_DEPOT) ?
				STR_1023_RAILROAD_TRAIN_DEPOT : STR_LANDINFO_WAYPOINT;
			break;
	}
}

static void ChangeTileOwner_Track(TileIndex tile, PlayerID old_player, PlayerID new_player)
{
	if (!IsTileOwner(tile, old_player)) return;

	if (new_player != OWNER_SPECTATOR) {
		SetTileOwner(tile, new_player);
	}	else {
		DoCommand(tile, 0, 0, DC_EXEC, CMD_LANDSCAPE_CLEAR);
	}
}

static const byte _fractcoords_behind[4] = { 0x8F, 0x8, 0x80, 0xF8 };
static const byte _fractcoords_enter[4] = { 0x8A, 0x48, 0x84, 0xA8 };
static const byte _deltacoord_leaveoffset[8] = {
	-1,  0,  1,  0, /* x */
	 0,  1,  0, -1  /* y */
};

static uint32 VehicleEnter_Track(Vehicle *v, TileIndex tile, int x, int y)
{
	byte fract_coord;
	byte fract_coord_leave;
	DiagDirection dir;
	int length;

	// this routine applies only to trains in depot tiles
	if (v->type != VEH_Train || !IsTileDepotType(tile, TRANSPORT_RAIL)) return 0;

	/* depot direction */
	dir = GetRailDepotDirection(tile);

	/* calculate the point where the following wagon should be activated */
	/* this depends on the length of the current vehicle */
	length = v->u.rail.cached_veh_length;

	fract_coord_leave =
		((_fractcoords_enter[dir] & 0x0F) +				// x
			(length + 1) * _deltacoord_leaveoffset[dir]) +
		(((_fractcoords_enter[dir] >> 4) +				// y
			((length + 1) * _deltacoord_leaveoffset[dir+4])) << 4);

	fract_coord = (x & 0xF) + ((y & 0xF) << 4);

	if (_fractcoords_behind[dir] == fract_coord) {
		/* make sure a train is not entering the tile from behind */
		return 8;
	} else if (_fractcoords_enter[dir] == fract_coord) {
		if (DiagDirToDir(ReverseDiagDir(dir)) == v->direction) {
			/* enter the depot */
			v->u.rail.track = 0x80,
			v->vehstatus |= VS_HIDDEN; /* hide it */
			v->direction = ReverseDir(v->direction);
			if (v->next == NULL)
				TrainEnterDepot(v, tile);
			v->tile = tile;
			InvalidateWindow(WC_VEHICLE_DEPOT, tile);
			return 4;
		}
	} else if (fract_coord_leave == fract_coord) {
		if (DiagDirToDir(dir) == v->direction) {
			/* leave the depot? */
			if ((v = v->next) != NULL) {
				v->vehstatus &= ~VS_HIDDEN;
				v->u.rail.track = (DiagDirToAxis(dir) == AXIS_X ? 1 : 2);
			}
		}
	}

	return 0;
}

void InitializeRail(void)
{
	_last_built_train_depot_tile = 0;
}

const TileTypeProcs _tile_type_rail_procs = {
	DrawTile_Track,						/* draw_tile_proc */
	GetSlopeZ_Track,					/* get_slope_z_proc */
	ClearTile_Track,					/* clear_tile_proc */
	GetAcceptedCargo_Track,		/* get_accepted_cargo_proc */
	GetTileDesc_Track,				/* get_tile_desc_proc */
	GetTileTrackStatus_Track,	/* get_tile_track_status_proc */
	ClickTile_Track,					/* click_tile_proc */
	AnimateTile_Track,				/* animate_tile_proc */
	TileLoop_Track,						/* tile_loop_clear */
	ChangeTileOwner_Track,		/* change_tile_owner_clear */
	NULL,											/* get_produced_cargo_proc */
	VehicleEnter_Track,				/* vehicle_enter_tile_proc */
	GetSlopeTileh_Track,			/* get_slope_tileh_proc */
};