train_cmd.c
author tron
Thu, 27 Jan 2005 12:52:20 +0000
changeset 1192 2649bd4e556a
parent 1179 ce0a75460808
child 1196 67f7f3017d99
permissions -rw-r--r--
(svn r1696) Use GetTileSlope() instead of FindLandscapeHeightByTile() where it is sufficient. FindLandscapeHeightByTile() uses GetTileSlope() internally and adds some more info, which is discarded in these cases.
While touching the code make a bit more clear how GetBridgeHeight() works.
#include "stdafx.h"
#include "ttd.h"
#include "table/strings.h"
#include "map.h"
#include "vehicle.h"
#include "command.h"
#include "pathfind.h"
#include "station.h"
#include "table/train_cmd.h"
#include "gfx.h"
#include "news.h"
#include "engine.h"
#include "player.h"
#include "sound.h"

#define is_firsthead_sprite(spritenum) \
	(is_custom_sprite(spritenum) \
		? is_custom_firsthead_sprite(spritenum) \
		: _engine_sprite_add[spritenum] == 0)

static bool TrainCheckIfLineEnds(Vehicle *v);

static const byte _vehicle_initial_x_fract[4] = {10,8,4,8};
static const byte _vehicle_initial_y_fract[4] = {8,4,8,10};
static const byte _state_dir_table[4] = { 0x20, 8, 0x10, 4 };

static const byte _signal_onedir[14] = {
	0x80, 0x80, 0x80, 0x20, 0x40, 0x10, 0, 0,
	0x40, 0x40, 0x40, 0x10, 0x80, 0x20
};

static const byte _signal_otherdir[14] = {
	0x40, 0x40, 0x40, 0x10, 0x80, 0x20, 0, 0,
	0x80, 0x80, 0x80, 0x20, 0x40, 0x10
};

static const byte _curve_neighbours45[8][2] = {
	{7, 1},
	{0, 2},
	{1, 3},
	{2, 4},
	{3, 5},
	{4, 6},
	{5, 7},
	{6, 0},
};

static const byte _curve_neighbours90[8][2] = {
	{6, 2},
	{7, 3},
	{0, 4},
	{1, 5},
	{2, 6},
	{3, 7},
	{4, 0},
	{5, 1},
};

enum AccelType {
	AM_ACCEL,
	AM_BRAKE
};

//new acceleration
static int GetTrainAcceleration(Vehicle *v, bool mode)
{
	Vehicle *u = v;
	int num = 0;	//number of vehicles, change this into the number of axles later
	int power = 0;
	int mass = 0;
	int max_speed = 2000;
	int area = 120;
	int friction = 35; //[1e-3]
	int drag_coeff = 20;	//[1e-4]
	int incl = 0;
	int resistance;
	int speed = v->cur_speed; //[mph]
	int force = 0x3FFFFFFF;
	int pos = 0;
	int lastpos = -1;
	int curvecount[2] = {0, 0};
	int *dist = NULL;
	int sum = 0;
	int numcurve = 0;
	int i;

	speed *= 10;
	speed /= 16;

	//first find the curve speed limit
	for (; u->next != NULL; u = u->next, pos++) {
		int dir = u->direction;
		int ndir = u->next->direction;

		for (i = 0; i < 2; i++) {
			if ( _curve_neighbours45[dir][i] == ndir) {
				curvecount[i]++;
				if (lastpos != -1) {
					dist = realloc(dist, sizeof(int) * ++numcurve);
					dist[numcurve - 1] = pos - lastpos;
					if (pos - lastpos == 1) {
						max_speed = 88;
					}
				}
				lastpos = pos;
			}
		}

		//if we have a 90 degree turn, fix the speed limit to 60
		if ( _curve_neighbours90[dir][0] == ndir || _curve_neighbours90[dir][1] == ndir) {
			max_speed = 61;
		}
	}

	for(i = 0; i < numcurve; i++) {
		sum += dist[i];
	}

	if (numcurve > 0) {
		sum /= numcurve;
	}

	if ((curvecount[0] != 0 || curvecount[1] != 0) && (max_speed > 88)) {
		int total = curvecount[0] + curvecount[1];
		if (curvecount[0] == 1 && curvecount[1] == 1) {
			max_speed = 0xFFFF;
		} else if (total > 1) {
			max_speed = 232 - (13 - clamp(sum, 1, 12)) * (13 - clamp(sum, 1, 12));
		}
	}

	max_speed += (max_speed / 2) * v->u.rail.railtype;

	if (IsTileType(v->tile, MP_STATION) && v->subtype == TS_Front_Engine) {
		static const TileIndexDiffC _station_dir_from_vdir[] = {
			{0, 0}, {-1, 0}, {0, 0}, {0, 1}, {0, 0}, {1, 0}, {0, 0}, {0, -1}
		};

		if (((v->current_order.station == _map2[v->tile]) || !(v->current_order.flags & OF_NON_STOP)) && v->last_station_visited != _map2[v->tile]) {
			int station_length = 0;
			TileIndex tile = v->tile;
			int delta_v;

			max_speed = 120;
			do {
				station_length++;
				tile = TILE_ADD(tile, ToTileIndexDiff(_station_dir_from_vdir[v->direction]));
			} while (IsTileType(tile, MP_STATION));

			delta_v = v->cur_speed / (station_length + 1);
			if (v->max_speed > (v->cur_speed - delta_v))
				max_speed = v->cur_speed - (delta_v / 10);

			max_speed = max(max_speed, 25 * station_length);
		}
	}

	for (u = v; u != NULL; u = u->next) {
		const RailVehicleInfo *rvi = RailVehInfo(u->engine_type);
		int vmass;

		num++;
		power += rvi->power * 746;	//[W]
		drag_coeff += 3;

		if (rvi->max_speed != 0)
			max_speed = min(rvi->max_speed, max_speed);

		if (u->u.rail.track == 0x80)
			max_speed = 61;

		vmass = rvi->weight;  //[t]
		vmass += (_cargoc.weights[u->cargo_type] * u->cargo_count) / 16;
		mass += vmass; //[t]

		if (!IsTileType(u->tile, MP_TUNNELBRIDGE)) {
			if (HASBIT(u->u.rail.flags, VRF_GOINGUP)) {
				incl += vmass * 60;		//3% slope, quite a bit actually
			} else if (HASBIT(u->u.rail.flags, VRF_GOINGDOWN)) {
				incl -= vmass * 60;
			}
		}
	}


	// these are shown in the UI
	v->u.rail.cached_weight = mass;
	v->u.rail.cached_power = power / 746;
	v->max_speed = max_speed;


	if (v->u.rail.railtype != 2) {
		resistance = 13 * mass / 10;
		resistance += 60 * num;
		resistance += friction * mass * speed / 1000;
		resistance += (area * drag_coeff * speed * speed) / 10000;
	} else
		resistance = (area * (drag_coeff / 2) * speed * speed) / 10000;
	resistance += incl;
	resistance *= 4; //[N]

	if (speed > 0) {
		switch (v->u.rail.railtype) {
			case 0:
			case 1:
			{
				force = power / speed; //[N]
				force *= 22;
				force /= 10;
			} break;
			case 2:
				force = power / 25;
			break;
		}
	} else
		//"kickoff" acceleration
		force = resistance * 10;

	if (force <= 0) force = 10000;

	if (v->u.rail.railtype != 2)
		force = min(force, mass * 10 * 200);

	if (mode == AM_ACCEL) {
		return (force - resistance) / (mass * 4);
	} else {
		return min((-force - resistance) /(mass * 4), (10000 / (mass * 4)));
	}
}

void UpdateTrainAcceleration(Vehicle *v)
{
	uint acc, power=0, max_speed=5000, weight=0;
	Vehicle *u = v;

	assert(v->subtype == TS_Front_Engine);

	// compute stuff like max speed, power, and weight.
	do {
		const RailVehicleInfo *rvi = RailVehInfo(u->engine_type);

		// power is sum of the power for all engines
		power += rvi->power;

		// limit the max speed to the speed of the slowest vehicle.
		if (rvi->max_speed && rvi->max_speed <= max_speed) max_speed = rvi->max_speed;

		// weight is the sum of the weight of the wagon and the weight of the cargo.
		weight += rvi->weight;
		weight += (_cargoc.weights[u->cargo_type] * u->cargo_count) >> 4;

	} while ( (u=u->next) != NULL);

	// these are shown in the UI
	v->u.rail.cached_weight = weight;
	v->u.rail.cached_power = power;
	v->max_speed = max_speed;

	assert(weight != 0);

	// compute acceleration
	acc = power / weight * 4;

	if (acc >= 255) acc=255;
	if (acc == 0) acc++;

	v->acceleration = (byte)acc;
}

int GetTrainImage(Vehicle *v, byte direction)
{
	int img = v->spritenum;
	int base;

	if (is_custom_sprite(img)) {
		base = GetCustomVehicleSprite(v, direction + 4 * is_custom_secondhead_sprite(img));
		if (base) return base;
		img = _engine_original_sprites[v->engine_type];
	}

	base = _engine_sprite_base[img] + ((direction + _engine_sprite_add[img]) & _engine_sprite_and[img]);

	if (v->cargo_count >= (v->cargo_cap >> 1))
		base += _wagon_full_adder[img];
	return base;
}

void DrawTrainEngine(int x, int y, int engine, uint32 image_ormod)
{
	const RailVehicleInfo *rvi = RailVehInfo(engine);

	int img = rvi->image_index;
	uint32 image = 0;

	if (is_custom_sprite(img)) {
		image = GetCustomVehicleIcon(engine, 6);
		if (!image) img = _engine_original_sprites[engine];
	}
	if (!image) {
		image = (6 & _engine_sprite_and[img]) + _engine_sprite_base[img];
	}

	if (rvi->flags & RVI_MULTIHEAD) {
		DrawSprite(image | image_ormod, x-14, y);
		x += 15;
		image = 0;
		if (is_custom_sprite(img)) {
			image = GetCustomVehicleIcon(engine, 2);
			if (!image) img = _engine_original_sprites[engine];
		}
		if (!image) {
			image = ((6 + _engine_sprite_add[img+1]) & _engine_sprite_and[img+1]) + _engine_sprite_base[img+1];
		}
	}
	DrawSprite(image | image_ormod, x, y);
}

void DrawTrainEngineInfo(int engine, int x, int y, int maxw)
{
	const RailVehicleInfo *rvi = RailVehInfo(engine);
	int cap;
	uint multihead = ((rvi->flags & RVI_MULTIHEAD) ? 1 : 0);

	SetDParam(0, ((_price.build_railvehicle >> 3) * rvi->base_cost) >> 5);
	SetDParam(2, rvi->max_speed * 10 >> 4);
	SetDParam(3, rvi->power << multihead);
	SetDParam(1, rvi->weight << multihead);

	SetDParam(4, (rvi->running_cost_base * _price.running_rail[rvi->engclass] >> 8) << multihead);

	cap = rvi->capacity;
	SetDParam(5, STR_8838_N_A);
	if (cap != 0) {
		SetDParam(6, cap << multihead);
		SetDParam(5, _cargoc.names_long_p[rvi->cargo_type]);
	}
	DrawStringMultiCenter(x, y, STR_885B_COST_WEIGHT_T_SPEED_POWER, maxw);
}


static int32 CmdBuildRailWagon(uint engine, uint tile, uint32 flags)
{
	int32 value;
	Vehicle *v;
	const RailVehicleInfo *rvi;
	int dir;
	const Engine *e;
	int x,y;

	SET_EXPENSES_TYPE(EXPENSES_NEW_VEHICLES);

	rvi = RailVehInfo(engine);
	value = (rvi->base_cost * _price.build_railwagon) >> 8;

	if (!(flags & DC_QUERY_COST)) {
		_error_message = STR_00E1_TOO_MANY_VEHICLES_IN_GAME;

		v = AllocateVehicle();
		if (v == NULL)
			return CMD_ERROR;

		if (flags & DC_EXEC) {
			byte img = rvi->image_index;
			Vehicle *u, *w;

			v->spritenum = img;

			u = NULL;

			FOR_ALL_VEHICLES(w) {
				if (w->type == VEH_Train && w->tile == (TileIndex)tile &&
				    w->subtype == TS_Free_Car && w->engine_type == engine) {
					u = GetLastVehicleInChain(w);
					break;
				}
			}

			v->engine_type = engine;

			dir = _map5[tile] & 3;

			v->direction = (byte)(dir*2+1);
			v->tile = (TileIndex)tile;

			x = TileX(tile) * 16 | _vehicle_initial_x_fract[dir];
			y = TileY(tile) * 16 | _vehicle_initial_y_fract[dir];

			v->x_pos = x;
			v->y_pos = y;
			v->z_pos = GetSlopeZ(x,y);
			v->owner = _current_player;
			v->z_height = 6;
			v->u.rail.track = 0x80;
			v->vehstatus = VS_HIDDEN | VS_DEFPAL;

			v->subtype = TS_Free_Car;
			if (u != NULL) {
				u->next = v;
				v->subtype = TS_Not_First;
				v->u.rail.first_engine = u->u.rail.first_engine;
				if (v->u.rail.first_engine == 0xffff && u->subtype == TS_Front_Engine )
					v->u.rail.first_engine = u->engine_type;
			} else {
				v->u.rail.first_engine = 0xffff;
			}

			v->cargo_type = rvi->cargo_type;
			v->cargo_cap = rvi->capacity;
			v->value = value;
//			v->day_counter = 0;

			e = &_engines[engine];
			v->u.rail.railtype = e->railtype;

			v->build_year = _cur_year;
			v->type = VEH_Train;
			v->cur_image = 0xAC2;

			_new_wagon_id = v->index;

			VehiclePositionChanged(v);

			InvalidateWindow(WC_VEHICLE_DEPOT, v->tile);
		}
	}

	return value;
}

// Move all free vehicles in the depot to the train
static void NormalizeTrainVehInDepot(Vehicle *u)
{
	Vehicle *v;
	FOR_ALL_VEHICLES(v) {
		if (v->type == VEH_Train && v->subtype == TS_Free_Car &&
				v->tile == u->tile &&
				v->u.rail.track == 0x80) {
			if (DoCommandByTile(0,v->index | (u->index<<16), 1, DC_EXEC, CMD_MOVE_RAIL_VEHICLE) == CMD_ERROR)
				break;
		}
	}
}

static const byte _railveh_unk1[] = {
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 1, 1, 0, 0, 0,
	0, 0, 0, 0, 1, 0, 1, 0,
	0, 1, 1, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 1,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0,
};

static const byte _railveh_score[] = {
	1, 4, 7, 19, 20, 30, 31, 19,
	20, 21, 22, 10, 11, 30, 31, 32,
	33, 34, 35, 29, 45, 32, 50, 40,
	41, 51, 52, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 60, 62,
	63, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 70, 71, 72, 73,
	74, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0,
};


int32 EstimateTrainCost(const RailVehicleInfo *rvi)
{
	return (rvi->base_cost * (_price.build_railvehicle >> 3)) >> 5;
}

void AddRearEngineToMultiheadedTrain(Vehicle *v, Vehicle *u, bool building)
{
	u->direction = v->direction;
	u->owner = v->owner;
	u->tile = v->tile;
	u->x_pos = v->x_pos;
	u->y_pos = v->y_pos;
	u->z_pos = v->z_pos;
	u->z_height = 6;
	u->u.rail.track = 0x80;
	v->u.rail.first_engine = 0xffff;
	u->vehstatus = v->vehstatus & ~VS_STOPPED;
	u->subtype = TS_Not_First;
	u->spritenum = v->spritenum + 1;
	u->cargo_type = v->cargo_type;
	u->cargo_cap = v->cargo_cap;
	u->u.rail.railtype = v->u.rail.railtype;
	if (building) v->next = u;
	u->engine_type = v->engine_type;
	u->build_year = v->build_year;
	if (building)
		v->value = u->value = v->value >> 1;
	else
		u->value = v->value;
	u->type = VEH_Train;
	u->cur_image = 0xAC2;
	VehiclePositionChanged(u);
}

/* Build a railroad vehicle
 * p1 = vehicle type id
 */

int32 CmdBuildRailVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
{
	const RailVehicleInfo *rvi;
	int value,dir;
	Vehicle *v, *u;
	byte unit_num;
	Engine *e;
	uint tile;

	_cmd_build_rail_veh_var1 = 0;

	SET_EXPENSES_TYPE(EXPENSES_NEW_VEHICLES);

	tile = TILE_FROM_XY(x,y);
	rvi = RailVehInfo(p1);

	if (rvi->flags & RVI_WAGON) {
		return CmdBuildRailWagon(p1, tile, flags);
	}

	value = EstimateTrainCost(rvi);

	if (!(flags & DC_QUERY_COST)) {
		v = AllocateVehicle();
		if (v == NULL || IsOrderPoolFull())
			return_cmd_error(STR_00E1_TOO_MANY_VEHICLES_IN_GAME);

		unit_num = GetFreeUnitNumber(VEH_Train);
		if (unit_num > _patches.max_trains)
			return_cmd_error(STR_00E1_TOO_MANY_VEHICLES_IN_GAME);

		if (flags & DC_EXEC) {
			v->unitnumber = unit_num;

			dir = _map5[tile] & 3;

			v->direction = (byte)(dir*2+1);
			v->tile = (TileIndex)tile;
			v->owner = _current_player;
			v->x_pos = (x |= _vehicle_initial_x_fract[dir]);
			v->y_pos = (y |= _vehicle_initial_y_fract[dir]);
			v->z_pos = GetSlopeZ(x,y);
			v->z_height = 6;
			v->u.rail.track = 0x80;
			v->u.rail.first_engine = 0xffff;
			v->vehstatus = VS_HIDDEN | VS_STOPPED | VS_DEFPAL;
			v->spritenum = rvi->image_index;
			v->cargo_type = rvi->cargo_type;
			v->cargo_cap = rvi->capacity;
			v->max_speed = rvi->max_speed;
			v->value = value;
			v->last_station_visited = 0xFFFF;
			v->dest_tile = 0;

			v->engine_type = (byte)p1;
			e = &_engines[p1];

			v->reliability = e->reliability;
			v->reliability_spd_dec = e->reliability_spd_dec;
			v->max_age = e->lifelength * 366;

			v->string_id = STR_SV_TRAIN_NAME;
			v->u.rail.railtype = e->railtype;
			_new_train_id = v->index;

			v->service_interval = _patches.servint_trains;
			v->date_of_last_service = _date;
			v->build_year = _cur_year;
			v->type = VEH_Train;
			v->cur_image = 0xAC2;

			VehiclePositionChanged(v);

			if (rvi->flags&RVI_MULTIHEAD && (u = AllocateVehicle()) != NULL)
				AddRearEngineToMultiheadedTrain(v, u, true);

			UpdateTrainAcceleration(v);
			NormalizeTrainVehInDepot(v);

			InvalidateWindow(WC_VEHICLE_DEPOT, tile);
			RebuildVehicleLists();
			InvalidateWindow(WC_COMPANY, v->owner);
		}
	}
	_cmd_build_rail_veh_var1 = _railveh_unk1[p1];
	_cmd_build_rail_veh_score = _railveh_score[p1];

	InvalidateWindow(WC_REPLACE_VEHICLE, VEH_Train); // updates the replace Train window

	return value;
}


bool IsTrainDepotTile(TileIndex tile)
{
	return IsTileType(tile, MP_RAILWAY) &&
					(_map5[tile] & 0xFC) == 0xC0;
}

static bool IsTunnelTile(TileIndex tile)
{
	return IsTileType(tile, MP_TUNNELBRIDGE) &&
				 (_map5[tile]&0x80) == 0;
}


int CheckStoppedInDepot(Vehicle *v)
{
	int count;
	TileIndex tile = v->tile;

	/* check if stopped in a depot */
	if (!IsTrainDepotTile(tile) || v->cur_speed != 0) {
errmsg:
		_error_message = STR_881A_TRAINS_CAN_ONLY_BE_ALTERED;
		return -1;
	}

	count = 0;
	do {
		count++;
		if (v->u.rail.track != 0x80 || v->tile != (TileIndex)tile ||
				(v->subtype == TS_Front_Engine && !(v->vehstatus&VS_STOPPED)))
			goto errmsg;
	} while ( (v=v->next) != NULL);

	return count;
}

// unlink a rail wagon from the linked list.
// returns the new value of first
static Vehicle *UnlinkWagon(Vehicle *v, Vehicle *first)
{
	// unlinking the first vehicle of the chain?
	v->u.rail.first_engine = 0xffff;
	if (v == first) {
		Vehicle *u;
		if ((v=v->next) == NULL) return NULL;
		for (u=v; u; u=u->next) u->u.rail.first_engine = v->engine_type;
		v->subtype = TS_Free_Car;
		return v;
	} else {
		Vehicle *u;
		for(u=first; u->next!=v; u=u->next) {}
		u->next = v->next;
		return first;
	}
}

static Vehicle *FindGoodVehiclePos(Vehicle *src)
{
	Vehicle *dst;
	uint16 eng = src->engine_type;
	TileIndex tile = src->tile;

	FOR_ALL_VEHICLES(dst) {
		if (dst->type == VEH_Train && dst->subtype == TS_Free_Car && dst->tile==tile) {
			// check so all vehicles in the line have the same engine.
			Vehicle *v = dst;
			while (v->engine_type == eng) {
				if ((v = v->next) == NULL) return dst;
			}
		}
	}

	return NULL;
}

/* p1 & 0xffff= source vehicle index
   p1 & 0xffff0000 = what wagon to put the wagon AFTER, 0xffff0000 to make a new line
	 p2 & 1 = move all vehicles following the vehicle..
 */

int32 CmdMoveRailVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
{
	Vehicle *src, *dst, *src_head, *dst_head;
	bool is_loco;

	src = GetVehicle(p1 & 0xFFFF);
	if (src->type != VEH_Train) return CMD_ERROR;

	is_loco = !(RailVehInfo(src->engine_type)->flags & RVI_WAGON)
	          && is_firsthead_sprite(src->spritenum);

	// if nothing is selected as destination, try and find a matching vehicle to drag to.
	if (((int32)p1 >> 16) == -1) {
		dst = NULL;
		if (!is_loco) dst = FindGoodVehiclePos(src);
	} else {
		dst = GetVehicle(((int32)p1 >> 16));
	}

	// don't move the same vehicle..
	if (src == dst)
		return 0;

	/* the player must be the owner */
	if (!CheckOwnership(src->owner) || (dst!=NULL && !CheckOwnership(dst->owner)))
		return CMD_ERROR;

	/* locate the head of the two chains */
	src_head = GetFirstVehicleInChain(src);
	dst_head = NULL;
	if (dst != NULL) dst_head = GetFirstVehicleInChain(dst);

	/* check if all vehicles in the source train are stopped */
	if (CheckStoppedInDepot(src_head) < 0)
		return CMD_ERROR;

	/* check if all the vehicles in the dest train are stopped,
	 * and that the length of the dest train is no longer than XXX vehicles */
	if (dst_head != NULL) {
		int num = CheckStoppedInDepot(dst_head);
		if (num < 0)
			return CMD_ERROR;

		if (num > (_patches.mammoth_trains ? 100 : 9) && dst_head->subtype == TS_Front_Engine )
			return_cmd_error(STR_8819_TRAIN_TOO_LONG);

		// if it's a multiheaded vehicle we're dragging to, drag to the vehicle before..
		while (is_custom_secondhead_sprite(dst->spritenum)
		       || (!is_custom_sprite(dst->spritenum) && _engine_sprite_add[dst->spritenum] != 0)) {
			Vehicle *v = GetPrevVehicleInChain(dst);
			if (!v || src == v) break;
			dst = v;
		}

		assert(dst_head->tile == src_head->tile);
	}

	// when moving all wagons, we can't have the same src_head and dst_head
	if (p2 & 1 && src_head == dst_head)
		return 0;

	// moving a loco to a new line?, then we need to assign a unitnumber.
	if (dst == NULL && src->subtype != TS_Front_Engine && is_loco) {
		uint unit_num = GetFreeUnitNumber(VEH_Train);
		if (unit_num > _patches.max_trains)
			return_cmd_error(STR_00E1_TOO_MANY_VEHICLES_IN_GAME);

		if (flags & DC_EXEC)
			src->unitnumber = unit_num;
	}


	/* do it? */
	if (flags & DC_EXEC) {
		if (p2 & 1) {
			// unlink ALL wagons
			if (src != src_head) {
				Vehicle *v = src_head;
				while (v->next != src) v=v->next;
				v->next = NULL;
			}
		} else {
			// unlink single wagon from linked list
			UnlinkWagon(src, src_head);
			src->next = NULL;
		}

		if (dst == NULL) {
			// move the train to an empty line. for locomotives, we set the type to 0. for wagons, 4.
			if (is_loco) {
				if (src->subtype != TS_Front_Engine) {
					// setting the type to 0 also involves setting up the orders field.
					src->subtype = TS_Front_Engine;
					assert(src->orders == NULL);
					src->num_orders = 0;
				}
				dst_head = src;
			} else {
				src->subtype = TS_Free_Car;
			}
			src->u.rail.first_engine = 0xffff;
		} else {
			if (src->subtype == TS_Front_Engine) {
				// the vehicle was previously a loco. need to free the order list and delete vehicle windows etc.
				DeleteWindowById(WC_VEHICLE_VIEW, src->index);
				DeleteVehicleOrders(src);
			}

			src->subtype = TS_Not_First;
			src->unitnumber = 0; // doesn't occupy a unitnumber anymore.

			// setup first_engine
			src->u.rail.first_engine = dst->u.rail.first_engine;
			if (src->u.rail.first_engine == 0xffff && dst->subtype == TS_Front_Engine)
				src->u.rail.first_engine = dst->engine_type;

			// link in the wagon(s) in the chain.
			{
				Vehicle *v = src;
				while (v->next != NULL) {
					v->next->u.rail.first_engine = v->u.rail.first_engine;
					v = v->next;
				}
				v->next = dst->next;
			}
			dst->next = src;
		}

		if (src_head->subtype == TS_Front_Engine)
			UpdateTrainAcceleration(src_head);
		InvalidateWindow(WC_VEHICLE_DETAILS, src_head->index);

		if (dst_head) {
			if (dst_head->subtype == TS_Front_Engine)
				UpdateTrainAcceleration(dst_head);
			InvalidateWindow(WC_VEHICLE_DETAILS, dst_head->index);
		}

		InvalidateWindow(WC_VEHICLE_DEPOT, src_head->tile);
		RebuildVehicleLists();
	}

	return 0;
}

/* p1 = train to start / stop */
int32 CmdStartStopTrain(int x, int y, uint32 flags, uint32 p1, uint32 p2)
{
	Vehicle *v;

	v = GetVehicle(p1);

	if (!CheckOwnership(v->owner))
		return CMD_ERROR;

	if (flags & DC_EXEC) {
		v->u.rail.days_since_order_progr = 0;
		v->vehstatus ^= VS_STOPPED;
		InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, STATUS_BAR);
		InvalidateWindow(WC_VEHICLE_DEPOT, v->tile);
	}
	return 0;
}

// p1 = wagon/loco index
// p2 = mode
//   0: sell just the vehicle
//   1: sell the vehicle and all vehicles that follow it in the chain
//   2: when selling attached locos, rearrange all vehicles after it to separate lines.
int32 CmdSellRailWagon(int x, int y, uint32 flags, uint32 p1, uint32 p2)
{
	Vehicle *v, *first,*last;
	int32 cost;

	SET_EXPENSES_TYPE(EXPENSES_NEW_VEHICLES);

	v = GetVehicle(p1);

	if (!CheckOwnership(v->owner))
		return CMD_ERROR;

	// get first vehicle in chain
	first = v;
	if (first->subtype != TS_Front_Engine) {
		first = GetFirstVehicleInChain(first);
		last = GetLastVehicleInChain(first);
		//now if:
		// 1) we delete a whole a chain, and
		// 2) we don't actually try to delete the last engine
		// 3) the first and the last vehicle of that train are of the same type, and
		// 4) the first and the last vehicle of the chain are not identical
		// 5) and of "engine" type (i.e. not a carriage)
		// then let the last vehicle live
		if ( (p2 == 1) && (v != last) && ( last->engine_type == first->engine_type ) && (last != first) && (first->subtype == TS_Front_Engine) )
			last = GetPrevVehicleInChain(last);
		else
			last = NULL;
	} else {
		if (p2 != 1) {
			// sell last part of multiheaded?
			last = GetLastVehicleInChain(v);
			// Check if the end-part is the same engine and check if it is the rear-end
			if (last->engine_type != first->engine_type || is_firsthead_sprite(last->spritenum))
				last = NULL;
		} else {
			last = NULL;
		}
	}

	// make sure the vehicle is stopped in the depot
	if (CheckStoppedInDepot(first) < 0)
		return CMD_ERROR;


	if (flags & DC_EXEC) {
		// always redraw the depot. maybe redraw train list
		InvalidateWindow(WC_VEHICLE_DEPOT, first->tile);
		if (first->subtype == TS_Front_Engine) {
			RebuildVehicleLists();
		}
		// when selling an attached locomotive. we need to delete its window.
		if (v->subtype == TS_Front_Engine) {
			DeleteWindowById(WC_VEHICLE_VIEW, v->index);

			// rearrange all vehicles that follow to separate lines.
			if (p2 == 2) {
				Vehicle *u,*tmp;
				u = v->next;
				while (u != last) {
					tmp = u;
					u = u->next;
					DoCommandByTile(tmp->tile, tmp->index | ((-1)<<16), 0, DC_EXEC, CMD_MOVE_RAIL_VEHICLE);
				}
			}
		}

		// delete the vehicles
		cost = 0;
		for(;;) {
			Vehicle *tmp;

			assert(first);
			first = UnlinkWagon(v, first);
			cost -= v->value;
			tmp = v;
			DeleteVehicle(tmp);
			if ( v == last ) {
				last = NULL;
				break;
			}
			if ( (v=v->next) == last || p2 != 1) break;
		}

		// delete last vehicle of multiheaded train?
		if (last) {
			first = UnlinkWagon(last, first);
			cost -= last->value;
			DeleteVehicle(last);
		}

		// an attached train changed?
		if (first && first->subtype == TS_Front_Engine) {
			UpdateTrainAcceleration(first);
			InvalidateWindow(WC_VEHICLE_DETAILS, first->index);
		}
	} else {
		cost = 0;
		for(;;) {
			cost -= v->value;
			if ( v == last ) {
				last = NULL;
				break;
			}
			if ( (v=v->next) == last || p2 != 1) break;
		}
		if (last) cost -= last->value;
	}
	InvalidateWindow(WC_REPLACE_VEHICLE, VEH_Train); // updates the replace Train window

	return cost;
}

static void UpdateTrainDeltaXY(Vehicle *v, int direction)
{
#define MKIT(a,b,c,d) ((a&0xFF)<<24) | ((b&0xFF)<<16) | ((c&0xFF)<<8) | ((d&0xFF)<<0)
	static const uint32 _delta_xy_table[8] = {
		MKIT(3, 3, -1, -1),
		MKIT(3, 7, -1, -3),
		MKIT(3, 3, -1, -1),
		MKIT(7, 3, -3, -1),
		MKIT(3, 3, -1, -1),
		MKIT(3, 7, -1, -3),
		MKIT(3, 3, -1, -1),
		MKIT(7, 3, -3, -1),
	};
#undef MKIT

	uint32 x = _delta_xy_table[direction];

	v->x_offs = (byte)x;
	v->y_offs = (byte)(x>>=8);
	v->sprite_width = (byte)(x>>=8);
	v->sprite_height = (byte)(x>>=8);
}

static void UpdateVarsAfterSwap(Vehicle *v)
{
	UpdateTrainDeltaXY(v, v->direction);
	v->cur_image = GetTrainImage(v, v->direction);
	BeginVehicleMove(v);
	VehiclePositionChanged(v);
	EndVehicleMove(v);
}

static void SetLastSpeed(Vehicle *v, int spd) {
	int old = v->u.rail.last_speed;
	if (spd != old) {
		v->u.rail.last_speed = spd;
		if (_patches.vehicle_speed || !old != !spd)
			InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, STATUS_BAR);
	}
}

static void SwapTrainFlags(byte *swap_flag1, byte *swap_flag2)
{
	byte flag1, flag2;

	flag1 = *swap_flag1;
	flag2 = *swap_flag2;

	/* Clear the flags */
	CLRBIT(*swap_flag1, VRF_GOINGUP);
	CLRBIT(*swap_flag1, VRF_GOINGDOWN);
	CLRBIT(*swap_flag2, VRF_GOINGUP);
	CLRBIT(*swap_flag2, VRF_GOINGDOWN);

	/* Reverse the rail-flags (if needed) */
	if (HASBIT(flag1, VRF_GOINGUP)) {
		SETBIT(*swap_flag2, VRF_GOINGDOWN);
	} else if (HASBIT(flag1, VRF_GOINGDOWN)) {
		SETBIT(*swap_flag2, VRF_GOINGUP);
	}
	if (HASBIT(flag2, VRF_GOINGUP)) {
		SETBIT(*swap_flag1, VRF_GOINGDOWN);
	} else if (HASBIT(flag2, VRF_GOINGDOWN)) {
		SETBIT(*swap_flag1, VRF_GOINGUP);
	}
}

static void ReverseTrainSwapVeh(Vehicle *v, int l, int r)
{
	Vehicle *a, *b;

	/* locate vehicles to swap */
	for(a=v; l!=0; l--) { a = a->next; }
	for(b=v; r!=0; r--) { b = b->next; }

	if (a != b) {
		/* swap the hidden bits */
		{
			uint16 tmp = (a->vehstatus & ~VS_HIDDEN) | (b->vehstatus&VS_HIDDEN);
			b->vehstatus = (b->vehstatus & ~VS_HIDDEN) | (a->vehstatus&VS_HIDDEN);
			a->vehstatus = tmp;
		}

		/* swap variables */
		swap_byte(&a->u.rail.track, &b->u.rail.track);
		swap_byte(&a->direction, &b->direction);

		/* toggle direction */
		if (!(a->u.rail.track & 0x80)) a->direction ^= 4;
		if (!(b->u.rail.track & 0x80)) b->direction ^= 4;

		/* swap more variables */
		swap_int32(&a->x_pos, &b->x_pos);
		swap_int32(&a->y_pos, &b->y_pos);
		swap_tile(&a->tile, &b->tile);
		swap_byte(&a->z_pos, &b->z_pos);

		SwapTrainFlags(&a->u.rail.flags, &b->u.rail.flags);

		/* update other vars */
		UpdateVarsAfterSwap(a);
		UpdateVarsAfterSwap(b);
	} else {
		if (!(a->u.rail.track & 0x80)) a->direction ^= 4;
		UpdateVarsAfterSwap(a);
	}
}

/* Check if the vehicle is a train and is on the tile we are testing */
static void *TestTrainOnCrossing(Vehicle *v, void *data)
{
	if (v->tile != *(const TileIndex*)data || v->type != VEH_Train)
		return NULL;

	return v;
}

static void DisableTrainCrossing(TileIndex tile)
{
	/* Test if we have a rail/road-crossing */
	if (IsTileType(tile, MP_STREET) && (_map5[tile] & 0xF0) == 0x10) {
		/* Check if there is a train on the tile itself */
		if (VehicleFromPos(tile, &tile, TestTrainOnCrossing) == NULL) {
			/* If light is on, switch light off */
			if (_map5[tile] & 4) {
				_map5[tile] &= ~4;
				MarkTileDirtyByTile(tile);
			}
		}
	}
}

static void ReverseTrainDirection(Vehicle *v)
{
	int l = 0, r = -1;
	Vehicle *u;

	if (IsTrainDepotTile(v->tile))
		InvalidateWindow(WC_VEHICLE_DEPOT, v->tile);

	/* Check if we were approaching a rail/road-crossing */
	{
		TileIndex tile = v->tile;
		int t;
		/* Determine the non-diagonal direction in which we will exit this tile */
		t = v->direction >> 1;
		if (!(v->direction & 1) && v->u.rail.track != _state_dir_table[t]) {
			t = (t - 1) & 3;
		}
		/* Calculate next tile */
		tile += TileOffsByDir(t);

		/* Check if the train left a rail/road-crossing */
		DisableTrainCrossing(tile);
	}

	// count number of vehicles
	u = v;
	do r++; while ( (u = u->next) != NULL );

	/* swap start<>end, start+1<>end-1, ... */
	do {
		ReverseTrainSwapVeh(v, l++, r--);
	} while (l <= r);

	if (IsTrainDepotTile(v->tile))
		InvalidateWindow(WC_VEHICLE_DEPOT, v->tile);

	CLRBIT(v->u.rail.flags, VRF_REVERSING);
}

/* p1 = vehicle */
int32 CmdReverseTrainDirection(int x, int y, uint32 flags, uint32 p1, uint32 p2)
{
	Vehicle *v;

	v = GetVehicle(p1);

	if (!CheckOwnership(v->owner))
		return CMD_ERROR;

	_error_message = STR_EMPTY;

//	if (v->u.rail.track & 0x80 || IsTrainDepotTile(v->tile))
//		return CMD_ERROR;

	if (v->u.rail.crash_anim_pos != 0 || v->breakdown_ctr != 0)
		return CMD_ERROR;

	if (flags & DC_EXEC) {
		if (_patches.realistic_acceleration && v->cur_speed != 0) {
			TOGGLEBIT(v->u.rail.flags, VRF_REVERSING);
		} else {
			v->cur_speed = 0;
			SetLastSpeed(v, 0);
			ReverseTrainDirection(v);
		}
	}
	return 0;
}

int32 CmdForceTrainProceed(int x, int y, uint32 flags, uint32 p1, uint32 p2)
{
	Vehicle *v;

	v = GetVehicle(p1);

	if (!CheckOwnership(v->owner))
		return CMD_ERROR;

	if (flags & DC_EXEC)
		v->u.rail.force_proceed = 0x50;

	return 0;
}

// p1 = vehicle to refit
// p2 = new cargo (0xFF)
// p2 = skip check for stopped in hanger (0x0100)
int32 CmdRefitRailVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
{
	Vehicle *v;
	int32 cost;
	uint num;

	byte SkipStoppedInDepotCheck = (p2 & 0x100) >> 8;

	p2 = p2 & 0xFF;

	SET_EXPENSES_TYPE(EXPENSES_TRAIN_RUN);

	v = GetVehicle(p1);
	if (!CheckOwnership(v->owner) || ((CheckStoppedInDepot(v) < 0) && !(SkipStoppedInDepotCheck)))
		return CMD_ERROR;

	cost = 0;
	num = 0;

	do {
		/* XXX: We also refit all the attached wagons en-masse if they
		 * can be refitted. This is how TTDPatch does it.  TODO: Have
		 * some nice [Refit] button near each wagon. --pasky */
		if ((!(RailVehInfo(v->engine_type)->flags & RVI_WAGON)
		     || (_engine_refit_masks[v->engine_type] & (1 << p2)))
		    && (byte) p2 != v->cargo_type && v->cargo_cap != 0) {
			cost += (_price.build_railvehicle >> 8);
			num += v->cargo_cap;
			if (flags & DC_EXEC) {
		//autorefitted train cars wants to keep the cargo
		//it will be checked if the cargo is valid in CmdReplaceVehicle
				if (!(SkipStoppedInDepotCheck))
					v->cargo_count = 0;
				v->cargo_type = (byte)p2;
				InvalidateWindow(WC_VEHICLE_DETAILS, v->index);
			}
		}
	// SkipStoppedInDepotCheck is called by CmdReplace and it should only apply to the single car it is called for
	} while ( (v=v->next) != NULL || SkipStoppedInDepotCheck );

	_returned_refit_amount = num;

	return cost;
}

int GetDepotByTile(uint tile)
{
	Depot *d;
	int i=0;
	for(d=_depots; d->xy != (TileIndex)tile; d++) { i++; }
	return i;
}

typedef struct TrainFindDepotData {
	uint best_length;
	uint tile;
	byte owner;
} TrainFindDepotData;

static bool TrainFindDepotEnumProc(uint tile, TrainFindDepotData *tfdd, int track, uint length, byte *state)
{
	if (IsTileType(tile, MP_RAILWAY) && _map_owner[tile] == tfdd->owner) {
		if ((_map5[tile] & ~0x3) == 0xC0) {
			if (length < tfdd->best_length) {
				tfdd->best_length = length;
				tfdd->tile = tile;
			}
			return true;
		}

		// make sure the train doesn't run against a oneway signal
		if ((_map5[tile] & 0xC0) == 0x40) {
			if (!(_map3_lo[tile] & _signal_onedir[track]) && _map3_lo[tile] & _signal_otherdir[track])
				return true;
		}
	}

	// stop  searching if we've found a destination that is closer already.
	return length >= tfdd->best_length;
}

// returns the tile of a depot to goto to.
static TrainFindDepotData FindClosestTrainDepot(Vehicle *v)
{
	int i;
	TrainFindDepotData tfdd;
	uint tile = v->tile;

	tfdd.owner = v->owner;
	tfdd.best_length = (uint)-1;

	if (IsTrainDepotTile(tile)){
		tfdd.tile = tile;
		tfdd.best_length = 0;
		return tfdd;
	}

	if (v->u.rail.track == 0x40) { tile = GetVehicleOutOfTunnelTile(v); }

	if (!_patches.new_depot_finding) {
		// search in all directions
		for(i=0; i!=4; i++)
			NewTrainPathfind(tile, i, (TPFEnumProc*)TrainFindDepotEnumProc, &tfdd, NULL);
	} else {
		// search in the forward direction first.
		i = v->direction >> 1;
		if (!(v->direction & 1) && v->u.rail.track != _state_dir_table[i]) { i = (i - 1) & 3; }
		NewTrainPathfind(tile, i, (TPFEnumProc*)TrainFindDepotEnumProc, &tfdd, NULL);
		if (tfdd.best_length == (uint)-1){
			// search in backwards direction
			i = (v->direction^4) >> 1;
			if (!(v->direction & 1) && v->u.rail.track != _state_dir_table[i]) { i = (i - 1) & 3; }
			NewTrainPathfind(tile, i, (TPFEnumProc*)TrainFindDepotEnumProc, &tfdd, NULL);
		}
	}

	return tfdd;
}

int32 CmdTrainGotoDepot(int x, int y, uint32 flags, uint32 p1, uint32 p2)
{
	Vehicle *v = GetVehicle(p1);
	TrainFindDepotData tfdd;

	if (v->current_order.type == OT_GOTO_DEPOT) {
		if (flags & DC_EXEC) {
			if (v->current_order.flags & OF_UNLOAD) {
				v->u.rail.days_since_order_progr = 0;
				v->cur_order_index++;
			}

			v->current_order.type = OT_DUMMY;
			v->current_order.flags = 0;
			InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, STATUS_BAR);
		}
		return 0;
	}

	tfdd = FindClosestTrainDepot(v);
	if (tfdd.best_length == (uint)-1)
		return_cmd_error(STR_883A_UNABLE_TO_FIND_ROUTE_TO);

	if (flags & DC_EXEC) {
		v->dest_tile = tfdd.tile;
		v->current_order.type = OT_GOTO_DEPOT;
		v->current_order.flags = OF_NON_STOP | OF_FULL_LOAD;
		v->current_order.station = GetDepotByTile(tfdd.tile);
		InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, STATUS_BAR);
	}

	return 0;
}

/* p1 = vehicle
 * p2 = new service int
 */
int32 CmdChangeTrainServiceInt(int x, int y, uint32 flags, uint32 p1, uint32 p2)
{
	Vehicle *v = GetVehicle(p1);

	if (!CheckOwnership(v->owner))
		return CMD_ERROR;

	if (flags & DC_EXEC) {
		v->service_interval = (uint16)p2;
		InvalidateWindowWidget(WC_VEHICLE_DETAILS, v->index, 8);
	}

	return 0;
}

void OnTick_Train(void)
{
	_age_cargo_skip_counter = (_age_cargo_skip_counter == 0) ? 184 : (_age_cargo_skip_counter - 1);
}

static const int8 _vehicle_smoke_pos[16] = {
	-4, -4, -4, 0, 4, 4, 4, 0,
	-4,  0,  4, 4, 4, 0,-4,-4,
};

static void HandleLocomotiveSmokeCloud(Vehicle *v)
{
	Vehicle *u;

	if (v->vehstatus & VS_TRAIN_SLOWING || v->load_unload_time_rem != 0 || v->cur_speed < 2)
		return;

	u = v;

	do {
		int engtype = v->engine_type;

		// no smoke?
		if (RailVehInfo(engtype)->flags & 2
		    || _engines[engtype].railtype > 0
		    || (v->vehstatus&VS_HIDDEN) || (v->u.rail.track & 0xC0) )
			continue;

		switch (RailVehInfo(engtype)->engclass) {
		case 0:
			// steam smoke.
			if ( (v->tick_counter&0xF) == 0 && !IsTrainDepotTile(v->tile) && !IsTunnelTile(v->tile)) {
				CreateEffectVehicleRel(v,
					(_vehicle_smoke_pos[v->direction]),
					(_vehicle_smoke_pos[v->direction+8]),
					10,
					EV_STEAM_SMOKE);
			}
			break;

		case 1:
			// diesel smoke
			if (u->cur_speed <= 40 && !IsTrainDepotTile(v->tile) && !IsTunnelTile(v->tile) && (uint16)Random() <= 0x1E00) {
				CreateEffectVehicleRel(v, 0,0,10, EV_SMOKE_3);
			}
			break;

		case 2:
			// blue spark
			if ( (v->tick_counter&0x3) == 0 && !IsTrainDepotTile(v->tile) && !IsTunnelTile(v->tile) && (uint16)Random() <= 0x5B0) {
				CreateEffectVehicleRel(v, 0,0,10, EV_SMOKE_2);
			}
			break;
		}
	} while ( (v = v->next) != NULL );

}

static void TrainPlayLeaveStationSound(Vehicle *v)
{
	static const SoundFx sfx[] = {
		SND_04_TRAIN,
		SND_0A_TRAIN_HORN,
		SND_0A_TRAIN_HORN
	};

	int engtype = v->engine_type;

	switch (_engines[engtype].railtype) {
		case 0:
			SndPlayVehicleFx(sfx[RailVehInfo(engtype)->engclass], v);
			break;
		case 1:
			SndPlayVehicleFx(SND_47_MAGLEV_2, v);
			break;
		case 2:
			SndPlayVehicleFx(SND_41_MAGLEV, v);
			break;
	}
}

static bool CheckTrainStayInDepot(Vehicle *v)
{
	Vehicle *u;

	// bail out if not all wagons are in the same depot or not in a depot at all
	for (u = v; u != NULL; u = u->next)
		if (u->u.rail.track != 0x80 || u->tile != v->tile)
			return false;

	if (v->u.rail.force_proceed == 0) {
		if (++v->load_unload_time_rem < 37) {
			InvalidateWindowClasses(WC_TRAINS_LIST);
			return true;
		}

		v->load_unload_time_rem = 0;

		if (UpdateSignalsOnSegment(v->tile, v->direction)) {
			InvalidateWindowClasses(WC_TRAINS_LIST);
			return true;
		}
	}

	VehicleServiceInDepot(v);
	InvalidateWindowClasses(WC_TRAINS_LIST);
	TrainPlayLeaveStationSound(v);

	v->u.rail.track = 1;
	if (v->direction & 2)
		v->u.rail.track = 2;

	v->vehstatus &= ~VS_HIDDEN;
	v->cur_speed = 0;

	UpdateTrainDeltaXY(v, v->direction);
	v->cur_image = GetTrainImage(v, v->direction);
	VehiclePositionChanged(v);
	UpdateSignalsOnSegment(v->tile, v->direction);
	UpdateTrainAcceleration(v);
	InvalidateWindow(WC_VEHICLE_DEPOT, v->tile);

	return false;
}

typedef struct TrainTrackFollowerData {
	TileIndex dest_coords;
	int station_index; // station index we're heading for
	uint best_bird_dist;
	uint best_track_dist;
	byte best_track;
} TrainTrackFollowerData;

static bool TrainTrackFollower(uint tile, TrainTrackFollowerData *ttfd, int track, uint length, byte *state){
	if (IsTileType(tile, MP_RAILWAY) && (_map5[tile]&0xC0) == 0x40) {
		// the tile has a signal
		byte m3 = _map3_lo[tile];
		if (!(m3 & _signal_onedir[track])) {
			// if one way signal not pointing towards us, stop going in this direction.
			if (m3 & _signal_otherdir[track])
				return true;
		} else if (_map2[tile] & _signal_onedir[track]) {
			// green signal in our direction. either one way or two way.
			*state = true;
		} else if (m3 & _signal_otherdir[track]) {
			// two way signal. unless we passed another green signal on the way,
			// stop going in this direction.
			if (!*state) return true;
		}
	}

	// heading for nowhere?
	if (ttfd->dest_coords == 0)
		return false;

	// did we reach the final station?
 if ((ttfd->station_index == -1 && tile == ttfd->dest_coords) ||
  (IsTileType(tile, MP_STATION) && IS_BYTE_INSIDE(_map5[tile], 0, 8) && _map2[tile] == ttfd->station_index)) {
  /* We do not check for dest_coords if we have a station_index,
   * because in that case the dest_coords are just an
   * approximation of where the station is */
		// found station
		ttfd->best_bird_dist = 0;
		if (length < ttfd->best_track_dist) {
			ttfd->best_track_dist = length;
			ttfd->best_track = state[1];
		}
		return true;
	} else {
		uint dist;

		// we've actually found the destination already. no point searching in directions longer than this.
		if (ttfd->best_track_dist != (uint)-1)
			return length >= ttfd->best_track_dist;

		// didn't find station
		dist = GetTileDist(tile, ttfd->dest_coords);
		if (dist < ttfd->best_bird_dist) {
			ttfd->best_bird_dist = dist;
			ttfd->best_track = state[1];
		}
		return false;
	}
}

static void FillWithStationData(TrainTrackFollowerData *fd, Vehicle *v)
{
        fd->dest_coords = v->dest_tile;
        if (v->current_order.type == OT_GOTO_STATION)
                fd->station_index = v->current_order.station;
        else
                fd->station_index = -1;

}

static const byte _initial_tile_subcoord[6][4][3] = {
{{ 15, 8, 1 },{ 0, 0, 0 },{ 0, 8, 5 },{ 0, 0, 0 }},
{{  0, 0, 0 },{ 8, 0, 3 },{ 0, 0, 0 },{ 8,15, 7 }},
{{  0, 0, 0 },{ 7, 0, 2 },{ 0, 7, 6 },{ 0, 0, 0 }},
{{ 15, 8, 2 },{ 0, 0, 0 },{ 0, 0, 0 },{ 8,15, 6 }},
{{ 15, 7, 0 },{ 8, 0, 4 },{ 0, 0, 0 },{ 0, 0, 0 }},
{{  0, 0, 0 },{ 0, 0, 0 },{ 0, 8, 4 },{ 7,15, 0 }},
};

static const uint32 _reachable_tracks[4] = {
	0x10091009,
	0x00160016,
	0x05200520,
	0x2A002A00,
};

static const byte _search_directions[6][4] = {
	{ 0, 9, 2, 9 }, // track 1
	{ 9, 1, 9, 3 }, // track 2
	{ 9, 0, 3, 9 }, // track upper
	{ 1, 9, 9, 2 }, // track lower
	{ 3, 2, 9, 9 }, // track left
	{ 9, 9, 1, 0 }, // track right
};

static const byte _pick_track_table[6] = {1, 3, 2, 2, 0, 0};

/* choose a track */
static byte ChooseTrainTrack(Vehicle *v, uint tile, int direction, byte trackbits)
{
	TrainTrackFollowerData fd;
	int bits = trackbits;
	uint best_track;
#if 0
	int time = rdtsc();
	static float f;
#endif

	assert( (bits & ~0x3F) == 0);

	/* quick return in case only one possible direction is available */
	if (KILL_FIRST_BIT(bits) == 0)
		return FIND_FIRST_BIT(bits);

	FillWithStationData(&fd, v);

	if (_patches.new_pathfinding) {
		fd.best_bird_dist = (uint)-1;
		fd.best_track_dist = (uint)-1;
		fd.best_track = 0xFF;
		NewTrainPathfind(tile - TileOffsByDir(direction), direction, (TPFEnumProc*)TrainTrackFollower, &fd, NULL);

//		printf("Train %d %s\n", v->unitnumber, fd.best_track_dist == -1 ? "NOTFOUND" : "FOUND");

		if (fd.best_track == 0xff) {
			// blaha
			best_track = FIND_FIRST_BIT(bits);
		} else {
			best_track = fd.best_track & 7;
		}
	} else {
		int i, r;
		uint best_bird_dist  = 0;
		uint best_track_dist = 0;
		byte train_dir = v->direction & 3;


		best_track = -1;

		do {
			i = FIND_FIRST_BIT(bits);
			bits = KILL_FIRST_BIT(bits);

			fd.best_bird_dist = (uint)-1;
			fd.best_track_dist = (uint)-1;

			NewTrainPathfind(tile, _search_directions[i][direction], (TPFEnumProc*)TrainTrackFollower, &fd, NULL);
			if (best_track != (uint)-1) {
				if (best_track_dist == (uint)-1) {
					if (fd.best_track_dist == (uint)-1) {
						/* neither reached the destination, pick the one with the smallest bird dist */
						if (fd.best_bird_dist > best_bird_dist) goto bad;
						if (fd.best_bird_dist < best_bird_dist) goto good;
					} else {
						/* we found the destination for the first time */
						goto good;
					}
				} else {
					if (fd.best_track_dist == (uint)-1) {
						/* didn't find destination, but we've found the destination previously */
						goto bad;
					} else {
						/* both old & new reached the destination, compare track length */
						if (fd.best_track_dist > best_track_dist) goto bad;
						if (fd.best_track_dist < best_track_dist) goto good;
					}
				}

				/* if we reach this position, there's two paths of equal value so far.
				 * pick one randomly. */
				r = (byte)Random();
				if (_pick_track_table[i] == train_dir) r += 80;
				if (_pick_track_table[best_track] == train_dir) r -= 80;

				if (r <= 127) goto bad;
			}
	good:;
			best_track = i;
			best_bird_dist = fd.best_bird_dist;
			best_track_dist = fd.best_track_dist;
	bad:;
		} while (bits != 0);
//		printf("Train %d %s\n", v->unitnumber, best_track_dist == -1 ? "NOTFOUND" : "FOUND");
		assert(best_track != (uint)-1);
	}

#if 0
	time = rdtsc() - time;
	f = f * 0.99 + 0.01 * time;
	printf("PF time = %d %f\n", time, f);
#endif

	return best_track;
}


static bool CheckReverseTrain(Vehicle *v)
{
	TrainTrackFollowerData fd;
	int i, r;
	int best_track;
	uint best_bird_dist  = 0;
	uint best_track_dist = 0;
	uint reverse, reverse_best;

	if (_opt.diff.line_reverse_mode != 0 ||
			v->u.rail.track & 0xC0 ||
			!(v->direction & 1))
		return false;

	FillWithStationData(&fd, v);

	best_track = -1;
	reverse_best = reverse = 0;

	assert(v->u.rail.track);

	i = _search_directions[FIND_FIRST_BIT(v->u.rail.track)][v->direction>>1];

	while(true) {
		fd.best_bird_dist = (uint)-1;
		fd.best_track_dist = (uint)-1;

		NewTrainPathfind(v->tile, reverse ^ i, (TPFEnumProc*)TrainTrackFollower, &fd, NULL);

		if (best_track != -1) {
			if (best_bird_dist != 0) {
				if (fd.best_bird_dist != 0) {
					/* neither reached the destination, pick the one with the smallest bird dist */
					if (fd.best_bird_dist > best_bird_dist) goto bad;
					if (fd.best_bird_dist < best_bird_dist) goto good;
				} else {
					/* we found the destination for the first time */
					goto good;
				}
			} else {
				if (fd.best_bird_dist != 0) {
					/* didn't find destination, but we've found the destination previously */
					goto bad;
				} else {
					/* both old & new reached the destination, compare track length */
					if (fd.best_track_dist > best_track_dist) goto bad;
					if (fd.best_track_dist < best_track_dist) goto good;
				}
			}

			/* if we reach this position, there's two paths of equal value so far.
			 * pick one randomly. */
			r = (byte)Random();
			if (_pick_track_table[i] == (v->direction & 3)) r += 80;
			if (_pick_track_table[best_track] == (v->direction & 3)) r -= 80;
			if (r <= 127) goto bad;
		}
good:;
		best_track = i;
		best_bird_dist = fd.best_bird_dist;
		best_track_dist = fd.best_track_dist;
		reverse_best = reverse;
bad:;
		if (reverse != 0)
			break;
		reverse = 2;
	}

	return reverse_best != 0;
}

static bool ProcessTrainOrder(Vehicle *v)
{
	const Order *order;
	bool result;

	// These are un-interruptible
	if (v->current_order.type >= OT_GOTO_DEPOT &&
			v->current_order.type <= OT_LEAVESTATION) {
		// Let a depot order in the orderlist interrupt.
		if (v->current_order.type != OT_GOTO_DEPOT ||
				!(v->current_order.flags & OF_UNLOAD))
			return false;
	}

	if (v->current_order.type == OT_GOTO_DEPOT &&
			(v->current_order.flags & (OF_UNLOAD | OF_FULL_LOAD)) ==  (OF_UNLOAD | OF_FULL_LOAD) &&
			!VehicleNeedsService(v)) {
		v->cur_order_index++;
	}

	// check if we've reached the waypoint?
	if (v->current_order.type == OT_GOTO_WAYPOINT && v->tile == v->dest_tile) {
		v->cur_order_index++;
	}

	// check if we've reached a non-stop station while TTDPatch nonstop is enabled..
	if (_patches.new_nonstop && v->current_order.flags & OF_NON_STOP &&
			v->current_order.station == _map2[v->tile]) {
		v->cur_order_index++;
	}

	// Get the current order
	if (v->cur_order_index >= v->num_orders)
		v->cur_order_index = 0;

	order = GetVehicleOrder(v, v->cur_order_index);

	// If no order, do nothing.
	if (order == NULL) {
		v->current_order.type = OT_NOTHING;
		v->current_order.flags = 0;
		v->dest_tile = 0;
		return false;
	}

	// If it is unchanged, keep it.
	if (order->type    == v->current_order.type &&
			order->flags   == v->current_order.flags &&
			order->station == v->current_order.station)
		return false;

	// Otherwise set it, and determine the destination tile.
	v->current_order = *order;

	v->dest_tile = 0;

	result = false;
	switch (order->type) {
		case OT_GOTO_STATION:
			if (order->station == v->last_station_visited)
				v->last_station_visited = 0xFFFF;
			v->dest_tile = GetStation(order->station)->xy;
			result = CheckReverseTrain(v);
			break;

		case OT_GOTO_DEPOT:
			v->dest_tile = _depots[order->station].xy;
			result = CheckReverseTrain(v);
			break;

		case OT_GOTO_WAYPOINT:
			v->dest_tile = _waypoints[order->station].xy;
			result = CheckReverseTrain(v);
			break;
	}

	InvalidateVehicleOrder(v);

	return result;
}

static void MarkTrainDirty(Vehicle *v)
{
	do {
		v->cur_image = GetTrainImage(v, v->direction);
		MarkAllViewportsDirty(v->left_coord, v->top_coord, v->right_coord + 1, v->bottom_coord + 1);
	} while ( (v=v->next) != NULL);
}

static void HandleTrainLoading(Vehicle *v, bool mode)
{
	if (v->current_order.type == OT_NOTHING)
		return;

	if (v->current_order.type != OT_DUMMY) {
		if (v->current_order.type != OT_LOADING)
			return;

		if (mode)
			return;

		// don't mark the train as lost if we're loading on the final station.
		if (v->current_order.flags & OF_NON_STOP)
			v->u.rail.days_since_order_progr = 0;

		if (--v->load_unload_time_rem)
			return;

		if (v->current_order.flags & OF_FULL_LOAD && CanFillVehicle(v)) {
			v->u.rail.days_since_order_progr = 0; /* Prevent a train lost message for full loading trains */
			SET_EXPENSES_TYPE(EXPENSES_TRAIN_INC);
			if (LoadUnloadVehicle(v)) {
				InvalidateWindow(WC_TRAINS_LIST, v->owner);
				MarkTrainDirty(v);

				// need to update acceleration since the goods on the train changed.
				UpdateTrainAcceleration(v);
			}
			return;
		}

		TrainPlayLeaveStationSound(v);

		{
			Order b = v->current_order;
			v->current_order.type = OT_LEAVESTATION;
			v->current_order.flags = 0;

			// If this was not the final order, don't remove it from the list.
			if (!(b.flags & OF_NON_STOP))
				return;
		}
	}

	v->u.rail.days_since_order_progr = 0;
	v->cur_order_index++;
	InvalidateVehicleOrder(v);
}

static int UpdateTrainSpeed(Vehicle *v)
{
	uint spd;
	uint accel;

	if (v->vehstatus & VS_STOPPED || HASBIT(v->u.rail.flags, VRF_REVERSING)) {
		if (_patches.realistic_acceleration)
			accel = GetTrainAcceleration(v, AM_BRAKE) * 2;
		else
			accel = v->acceleration * -2;
	} else {
		if (_patches.realistic_acceleration)
			accel = GetTrainAcceleration(v, AM_ACCEL);
		else
			accel = v->acceleration;
	}

	spd = v->subspeed + accel * 2;
	v->subspeed = (byte)spd;
	{
		int tempmax = v->max_speed;
		if (v->cur_speed > v->max_speed)
			tempmax = v->cur_speed - (v->cur_speed / 10) - 1;
		v->cur_speed = spd = clamp(v->cur_speed + ((int)spd >> 8), 0, tempmax);
	}

	if (!(v->direction & 1)) spd = spd * 3 >> 2;

	spd += v->progress;
	v->progress = (byte)spd;
	return (spd >> 8);
}

static void TrainEnterStation(Vehicle *v, int station)
{
	Station *st;
	uint32 flags;

	v->last_station_visited = station;

	/* check if a train ever visited this station before */
	st = GetStation(station);
	if (!(st->had_vehicle_of_type & HVOT_TRAIN)) {
		st->had_vehicle_of_type |= HVOT_TRAIN;
		SetDParam(0, st->index);
		flags = (v->owner == _local_player) ? NEWS_FLAGS(NM_THIN, NF_VIEWPORT|NF_VEHICLE, NT_ARRIVAL_PLAYER, 0) : NEWS_FLAGS(NM_THIN, NF_VIEWPORT|NF_VEHICLE, NT_ARRIVAL_OTHER, 0);
		AddNewsItem(
			STR_8801_CITIZENS_CELEBRATE_FIRST,
			flags,
			v->index,
			0);
	}

	// Did we reach the final destination?
	if (v->current_order.type == OT_GOTO_STATION &&
			v->current_order.station == (byte)station) {
		// Yeah, keep the load/unload flags
		// Non Stop now means if the order should be increased.
		v->current_order.type = OT_LOADING;
		v->current_order.flags &= OF_FULL_LOAD | OF_UNLOAD;
		v->current_order.flags |= OF_NON_STOP;
	} else {
		// No, just do a simple load
		v->current_order.type = OT_LOADING;
		v->current_order.flags = 0;
	}
	v->current_order.station = 0;

	SET_EXPENSES_TYPE(EXPENSES_TRAIN_INC);
	if (LoadUnloadVehicle(v) != 0) {
		InvalidateWindow(WC_TRAINS_LIST, v->owner);
		MarkTrainDirty(v);
		UpdateTrainAcceleration(v);
	}
	InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, STATUS_BAR);
}

static byte AfterSetTrainPos(Vehicle *v, bool new_tile)
{
	byte new_z, old_z;

	// need this hint so it returns the right z coordinate on bridges.
	_get_z_hint = v->z_pos;
	new_z = GetSlopeZ(v->x_pos, v->y_pos);
	_get_z_hint = 0;

	old_z = v->z_pos;
	v->z_pos = new_z;

	if (new_tile) {
		CLRBIT(v->u.rail.flags, VRF_GOINGUP);
		CLRBIT(v->u.rail.flags, VRF_GOINGDOWN);

		if (new_z != old_z) {
			SETBIT(v->u.rail.flags, (new_z > old_z) ? VRF_GOINGUP : VRF_GOINGDOWN);
		}
	}

	VehiclePositionChanged(v);
	EndVehicleMove(v);
	return old_z;
}

static const byte _new_vehicle_direction_table[11] = {
	0, 7, 6, 0,
	1, 0, 5, 0,
	2, 3, 4,
};

static int GetNewVehicleDirectionByTile(uint new_tile, uint old_tile)
{
	uint offs = (TileY(new_tile) - TileY(old_tile) + 1) * 4 +
							TileX(new_tile) - TileX(old_tile) + 1;
	assert(offs < 11);
	return _new_vehicle_direction_table[offs];
}

static int GetNewVehicleDirection(Vehicle *v, int x, int y)
{
	uint offs = (y - v->y_pos + 1) * 4 + (x - v->x_pos + 1);
	assert(offs < 11);
	return _new_vehicle_direction_table[offs];
}

static int GetDirectionToVehicle(Vehicle *v, int x, int y)
{
	byte offs;

	x -= v->x_pos;
	if (x >= 0) {
		offs = (x > 2) ? 0 : 1;
	} else {
		offs = (x < -2) ? 2 : 1;
	}

	y -= v->y_pos;
	if (y >= 0) {
		offs += ((y > 2) ? 0 : 1) * 4;
	} else {
		offs += ((y < -2) ? 2 : 1) * 4;
	}

	assert(offs < 11);
	return _new_vehicle_direction_table[offs];
}

/* Check if the vehicle is compatible with the specified tile */
static bool CheckCompatibleRail(const Vehicle *v, TileIndex tile)
{
	switch (TileType(tile)) {
		case MP_RAILWAY:
		case MP_STATION:
			// normal tracks, jump to owner check
			break;

		case MP_TUNNELBRIDGE:
			if ((_map5[tile] & 0xC0) == 0xC0) { // is bridge middle part?
				uint height;
				uint tileh = GetTileSlope(tile, &height);

				// correct Z position of a train going under a bridge on slopes
				if (CORRECT_Z(tileh)) height += 8;

				if (v->z_pos != height) return true; // train is going over bridge
			}
			break;

		case MP_STREET:
			// tracks over roads, do owner check of tracks (_map_owner[tile])
			return
				_map_owner[tile] == v->owner &&
				(v->subtype != TS_Front_Engine || (_map3_hi[tile] & 0xF) == v->u.rail.railtype);

		default:
			return true;
	}

	return
		_map_owner[tile] == v->owner &&
		(v->subtype != TS_Front_Engine || (_map3_lo[tile] & 0xF) == v->u.rail.railtype);
}

typedef struct {
	byte small_turn, large_turn;
	byte z_up; // fraction to remove when moving up
	byte z_down; // fraction to remove when moving down
} RailtypeSlowdownParams;

static const RailtypeSlowdownParams _railtype_slowdown[3] = {
	// normal accel
	{256/4, 256/2, 256/4, 2}, // normal
	{256/4, 256/2, 256/4, 2}, // monorail
	{0,     256/2, 256/4, 2}, // maglev
};

/* Modify the speed of the vehicle due to a turn */
static void AffectSpeedByDirChange(Vehicle *v, byte new_dir)
{
	byte diff;
	const RailtypeSlowdownParams *rsp;

	if (_patches.realistic_acceleration || (diff = (v->direction - new_dir) & 7) == 0)
		return;

	rsp = &_railtype_slowdown[v->u.rail.railtype];
	v->cur_speed -= ((diff == 1 || diff == 7) ? rsp->small_turn : rsp->large_turn) * v->cur_speed >> 8;
}

/* Modify the speed of the vehicle due to a change in altitude */
static void AffectSpeedByZChange(Vehicle *v, byte old_z)
{
	const RailtypeSlowdownParams *rsp;
	if (old_z == v->z_pos || _patches.realistic_acceleration)
		return;

	rsp = &_railtype_slowdown[v->u.rail.railtype];

	if (old_z < v->z_pos) {
		v->cur_speed -= (v->cur_speed * rsp->z_up >> 8);
	} else {
		uint16 spd = v->cur_speed + rsp->z_down;
		if (spd <= v->max_speed)
			v->cur_speed = spd;
	}
}

static const byte _otherside_signal_directions[14] = {
	1, 3, 1, 3, 5, 3, 0, 0,
	5, 7, 7, 5, 7, 1,
};

static void TrainMovedChangeSignals(uint tile, int dir)
{
	int i;
	if (IsTileType(tile, MP_RAILWAY) && (_map5[tile] & 0xC0) == 0x40) {
		i = FindFirstBit2x64((_map5[tile]+(_map5[tile]<<8)) & _reachable_tracks[dir]);
		UpdateSignalsOnSegment(tile, _otherside_signal_directions[i]);
	}
}


typedef struct TrainCollideChecker {
	Vehicle *v, *v_skip;

} TrainCollideChecker;

static void *FindTrainCollideEnum(Vehicle *v, TrainCollideChecker *tcc)
{
	if (v == tcc->v || v == tcc->v_skip || v->type != VEH_Train || v->u.rail.track==0x80)
		return 0;

	if ( myabs(v->z_pos - tcc->v->z_pos) > 6 ||
			 myabs(v->x_pos - tcc->v->x_pos) >= 6 ||
			 myabs(v->y_pos - tcc->v->y_pos) >= 6)
				return NULL;
	return v;
}

static void SetVehicleCrashed(Vehicle *v)
{
	Vehicle *u;

	if (v->u.rail.crash_anim_pos != 0)
		return;

	v->u.rail.crash_anim_pos++;

	u = v;
	BEGIN_ENUM_WAGONS(v)
		v->vehstatus |= VS_CRASHED;
	END_ENUM_WAGONS(v)

	InvalidateWindowWidget(WC_VEHICLE_VIEW, u->index, STATUS_BAR);
}

static int CountPassengersInTrain(Vehicle *v)
{
	int num = 0;
	BEGIN_ENUM_WAGONS(v)
		if (v->cargo_type == CT_PASSENGERS) num += v->cargo_count;
	END_ENUM_WAGONS(v)
	return num;
}

/*
 * Checks whether the specified tried has a collision with another vehicle. If
 * so, destroys this vehicle, and the other vehicle if its subtype is 0 (TS_Front_Engine).
 * Reports the incident in a flashy news item, modifies station ratings and
 * plays a sound.
 */
static void CheckTrainCollision(Vehicle *v)
{
	TrainCollideChecker tcc;
	Vehicle *coll,*realcoll;
	int num;

	/* can't collide in depot */
	if (v->u.rail.track == 0x80)
		return;

	if ( !(v->u.rail.track == 0x40) )
		assert((uint)TILE_FROM_XY(v->x_pos, v->y_pos) == v->tile);

	tcc.v = v;
	tcc.v_skip = v->next;

	/* find colliding vehicle */
	realcoll = coll = VehicleFromPos(TILE_FROM_XY(v->x_pos, v->y_pos), &tcc, (VehicleFromPosProc*)FindTrainCollideEnum);
	if (coll == NULL)
		return;


	coll = GetFirstVehicleInChain(coll);

	/* it can't collide with its own wagons */
	if ( (v == coll) || ( (v->u.rail.track & 0x40) && ( (v->direction & 2) != (realcoll->direction & 2) ) ) )
		return;

	//two drivers + passangers killed in train v
	num = 2 + CountPassengersInTrain(v);
	if(!(coll->vehstatus&VS_CRASHED))
		//two drivers + passangers killed in train coll (if it was not crashed already)
		num += 2 + CountPassengersInTrain(coll);

	SetVehicleCrashed(v);
	if (coll->subtype == TS_Front_Engine)
		SetVehicleCrashed(coll);


	SetDParam(0, num);

	AddNewsItem(STR_8868_TRAIN_CRASH_DIE_IN_FIREBALL,
		NEWS_FLAGS(NM_THIN, NF_VIEWPORT|NF_VEHICLE, NT_ACCIDENT, 0),
		v->index,
		0);

	ModifyStationRatingAround(v->tile, v->owner, -160, 30);
	SndPlayVehicleFx(SND_13_BIG_CRASH, v);
}

static void *CheckVehicleAtSignal(Vehicle *v, void *data)
{
	uint32 d = (uint32)data;

	if (v->type == VEH_Train && v->subtype == TS_Front_Engine && v->tile == (TileIndex)(d >> 8)) {
		byte diff = (v->direction - (byte)d + 2) & 7;
		if (diff == 2 || (v->cur_speed <= 5 && diff <= 4))
			return (void*)1;
	}
	return 0;
}

static void TrainController(Vehicle *v)
{
	Vehicle *prev = NULL;
	GetNewVehiclePosResult gp;
	uint32 r, tracks,ts;
	int dir, i;
	byte chosen_dir;
	byte chosen_track;
	byte old_z;

	/* For every vehicle after and including the given vehicle */
	for(;;) {
		BeginVehicleMove(v);

		if (v->u.rail.track != 0x40) {
			/* Not inside tunnel */
			if (GetNewVehiclePos(v, &gp)) {
				/* Staying in the old tile */
				if (v->u.rail.track == 0x80) {
					/* inside depot */
					gp.x = v->x_pos;
					gp.y = v->y_pos;
				} else {
					/* is not inside depot */

					if (!TrainCheckIfLineEnds(v))
						return;

					r = VehicleEnterTile(v, gp.new_tile, gp.x, gp.y);
					if (r & 0x8)
						goto invalid_rail;
					if (r & 0x2) {
						TrainEnterStation(v, r >> 8);
						return;
					}

					if (v->current_order.type == OT_LEAVESTATION) {
						v->current_order.type = OT_NOTHING;
						v->current_order.flags = 0;
						InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, STATUS_BAR);
					}
				}
			} else {
				/* A new tile is about to be entered. */

				/* Determine what direction we're entering the new tile from */
				dir = GetNewVehicleDirectionByTile(gp.new_tile, gp.old_tile);
				assert(dir==1 || dir==3 || dir==5 || dir==7);

				/* Get the status of the tracks in the new tile and mask
				 * away the bits that aren't reachable. */
				ts = GetTileTrackStatus(gp.new_tile, TRANSPORT_RAIL) & _reachable_tracks[dir >> 1];

				/* Combine the from & to directions.
				 * Now, the lower byte contains the track status, and the byte at bit 16 contains
				 * the signal status. */
				tracks = ts|(ts >> 8);
				if ( (byte) tracks == 0)
					goto invalid_rail;

				/* Check if the new tile contrains tracks that are compatible
				 * with the current train, if not, bail out. */
				if (!CheckCompatibleRail(v, gp.new_tile))
					goto invalid_rail;

				if (prev == NULL) {
					/* Currently the locomotive is active. Determine which one of the
					 * available tracks to choose */
					chosen_track = 1 << ChooseTrainTrack(v, gp.new_tile, dir>>1, (byte)tracks);

					/* Check if it's a red signal and that force proceed is not clicked. */
					if ( (tracks>>16)&chosen_track && v->u.rail.force_proceed == 0) goto red_light;
				} else {
					static byte _matching_tracks[8] = {0x30, 1, 0xC, 2, 0x30, 1, 0xC, 2};

					/* The wagon is active, simply follow the prev vehicle. */
					chosen_track = (byte)(_matching_tracks[GetDirectionToVehicle(prev, gp.x, gp.y)] & tracks);
				}

				/* make sure chosen track is a valid track */
				assert(chosen_track==1 || chosen_track==2 || chosen_track==4 || chosen_track==8 || chosen_track==16 || chosen_track==32);

				/* Update XY to reflect the entrance to the new tile, and select the direction to use */
				{
					const byte *b = _initial_tile_subcoord[FIND_FIRST_BIT(chosen_track)][dir>>1];
					gp.x = (gp.x & ~0xF) | b[0];
					gp.y = (gp.y & ~0xF) | b[1];
					chosen_dir = b[2];
				}

				/* Call the landscape function and tell it that the vehicle entered the tile */
				r = VehicleEnterTile(v, gp.new_tile, gp.x, gp.y);
				if (r&0x8)
					goto invalid_rail;

				if (v->subtype == TS_Front_Engine) v->load_unload_time_rem = 0;

				if (!(r&0x4)) {
					v->tile = gp.new_tile;
					v->u.rail.track = chosen_track;
				}

				if (v->subtype == TS_Front_Engine)
					TrainMovedChangeSignals(gp.new_tile, dir>>1);

				/* Signals can only change when the first
				 * (above) or the last vehicle moves. */
				if (v->next == NULL)
					TrainMovedChangeSignals(gp.old_tile, (dir>>1) ^ 2);

				if (prev == NULL) {
					AffectSpeedByDirChange(v, chosen_dir);
				}

				v->direction = chosen_dir;
			}
		} else {
			/* in tunnel */
			GetNewVehiclePos(v, &gp);

			if (IsTileType(gp.new_tile, MP_TUNNELBRIDGE) &&
					!(_map5[gp.new_tile] & 0xF0)) {
				r = VehicleEnterTile(v, gp.new_tile, gp.x, gp.y);
				if (r & 0x4) goto common;
			}

			v->x_pos = gp.x;
			v->y_pos = gp.y;
			VehiclePositionChanged(v);
			if (prev == NULL)
				CheckTrainCollision(v);
			goto next_vehicle;
		}
common:;

		/* update image of train, as well as delta XY */
		dir = GetNewVehicleDirection(v, gp.x, gp.y);
		UpdateTrainDeltaXY(v, dir);
		v->cur_image = GetTrainImage(v, dir);

		v->x_pos = gp.x;
		v->y_pos = gp.y;

		/* update the Z position of the vehicle */
		old_z = AfterSetTrainPos(v, (gp.new_tile != gp.old_tile));

		if (prev == NULL) {
			/* This is the first vehicle in the train */
			AffectSpeedByZChange(v, old_z);
			CheckTrainCollision(v);
		}

next_vehicle:;
		/* continue with next vehicle */
		prev = v;
		if ((v=v->next) == NULL)
			return;
	}

invalid_rail:
	/* We've reached end of line?? */
	if (prev != NULL) {
		error("!Disconnecting train");
	}
	goto reverse_train_direction;

red_light: {
	/* We're in front of a red signal ?? */
		/* find the first set bit in ts. need to do it in 2 steps, since
		 * FIND_FIRST_BIT only handles 6 bits at a time. */
		i = FindFirstBit2x64(ts);

		if (!(_map3_lo[gp.new_tile] & _signal_otherdir[i])) {
			v->cur_speed = 0;
			v->subspeed = 0;
			v->progress = 255-100;
			if (++v->load_unload_time_rem < _patches.wait_oneway_signal * 20)
				return;
		} else if (_map3_lo[gp.new_tile] & _signal_onedir[i]){
			v->cur_speed = 0;
			v->subspeed = 0;
			v->progress = 255-10;
			if (++v->load_unload_time_rem < _patches.wait_twoway_signal * 73) {
				uint o_tile = gp.new_tile + TileOffsByDir(dir >> 1);
				/* check if a train is waiting on the other side */
				if (VehicleFromPos(o_tile, (void*)( (o_tile<<8) | (dir^4)), (VehicleFromPosProc*)CheckVehicleAtSignal) == NULL)
					return;
			}
		}
	}

reverse_train_direction:
	v->load_unload_time_rem = 0;
	v->cur_speed = 0;
	v->subspeed = 0;
	ReverseTrainDirection(v);

}

extern uint CheckTunnelBusy(uint tile, int *length);

static void DeleteLastWagon(Vehicle *v)
{
	Vehicle *u = v;
	int t;

	while (v->next != NULL) {
		u = v;
		v = v->next;
	}
	u->next = NULL;

	InvalidateWindow(WC_VEHICLE_DETAILS, v->index);
	DeleteWindowById(WC_VEHICLE_VIEW, v->index);
	RebuildVehicleLists();
	InvalidateWindow(WC_COMPANY, v->owner);

	BeginVehicleMove(v);
	EndVehicleMove(v);
	DeleteVehicle(v);

	if (!((t=v->u.rail.track) & 0xC0)) {
		SetSignalsOnBothDir(v->tile, FIND_FIRST_BIT(t));
	}

	/* Check if the wagon was on a road/rail-crossing and disable it if no others are on it */
	DisableTrainCrossing(v->tile);

	if (v->u.rail.track == 0x40) {
		int length;
		TileIndex endtile = CheckTunnelBusy(v->tile, &length);
		if ((v->direction == 1) || (v->direction == 5) )
			SetSignalsOnBothDir(v->tile,0);
			SetSignalsOnBothDir(endtile,0);
		if ((v->direction == 3) || (v->direction == 7) )
			SetSignalsOnBothDir(v->tile,1);
			SetSignalsOnBothDir(endtile,1);
	}
}

static void ChangeTrainDirRandomly(Vehicle *v)
{
	static int8 _random_dir_change[4] = { -1, 0, 0, 1};

	do {
		//I need to buffer the train direction
		if (!(v->u.rail.track & 0x40))
			v->direction = (v->direction + _random_dir_change[Random()&3]) & 7;
		if (!(v->vehstatus & VS_HIDDEN)) {
			BeginVehicleMove(v);
			UpdateTrainDeltaXY(v, v->direction);
			v->cur_image = GetTrainImage(v, v->direction);
			AfterSetTrainPos(v, false);
		}
	} while ( (v=v->next) != NULL);
}

static void HandleCrashedTrain(Vehicle *v)
{
	int state = ++v->u.rail.crash_anim_pos, index;
	uint32 r;
	Vehicle *u;

	if ( (state == 4) && (v->u.rail.track != 0x40) ) {
		CreateEffectVehicleRel(v, 4, 4, 8, EV_CRASHED_SMOKE);
	}

	if (state <= 200 && (uint16)(r=Random()) <= 0x2492) {
		index = (r * 10 >> 16);

		u = v;
		do {
			if (--index < 0) {
				r = Random();

				CreateEffectVehicleRel(u,
					2 + ((r>>8)&7),
					2 + ((r>>16)&7),
					5 + (r&7),
					EV_DEMOLISH);
				break;
			}
		} while ( (u=u->next) != NULL);
	}

	if (state <= 240 && !(v->tick_counter&3)) {
		ChangeTrainDirRandomly(v);
	}

	if (state >= 4440 && !(v->tick_counter&0x1F)) {
		DeleteLastWagon(v);
		InvalidateWindow(WC_REPLACE_VEHICLE, VEH_Train);
	}
}

static void HandleBrokenTrain(Vehicle *v)
{
	if (v->breakdown_ctr != 1) {
		v->breakdown_ctr = 1;
		v->cur_speed = 0;

		if (v->breakdowns_since_last_service != 255)
			v->breakdowns_since_last_service++;

		InvalidateWindow(WC_VEHICLE_VIEW, v->index);
		InvalidateWindow(WC_VEHICLE_DETAILS, v->index);

		SndPlayVehicleFx((_opt.landscape != LT_CANDY) ?
			SND_10_TRAIN_BREAKDOWN : SND_3A_COMEDY_BREAKDOWN_2, v);

		if (!(v->vehstatus & VS_HIDDEN)) {
			Vehicle *u = CreateEffectVehicleRel(v, 4, 4, 5, EV_BREAKDOWN_SMOKE);
			if (u)
				u->u.special.unk0 = v->breakdown_delay * 2;
		}
	}

	if (!(v->tick_counter & 3)) {
		if (!--v->breakdown_delay) {
			v->breakdown_ctr = 0;
			InvalidateWindow(WC_VEHICLE_VIEW, v->index);
		}
	}
}

static const byte _breakdown_speeds[16] = {
	225, 210, 195, 180, 165, 150, 135, 120, 105, 90, 75, 60, 45, 30, 15, 15
};

static bool TrainCheckIfLineEnds(Vehicle *v)
{
	uint tile;
	uint x,y;
	int t;
	uint32 ts;

	if ((uint)(t=v->breakdown_ctr) > 1) {
		v->vehstatus |= VS_TRAIN_SLOWING;

		t = _breakdown_speeds[ ((~t) >> 4) & 0xF];
		if ((uint16)t <= v->cur_speed)
			v->cur_speed = t;
	} else {
		v->vehstatus &= ~VS_TRAIN_SLOWING;
	}

	// exit if inside a tunnel
	if (v->u.rail.track & 0x40)
		return true;

	tile = v->tile;

	// tunnel entrance?
	if (IsTileType(tile, MP_TUNNELBRIDGE) &&
			(_map5[tile] & 0xF0) == 0 && (byte)((_map5[tile] & 3)*2+1) == v->direction)
				return true;

	// depot?
	/* XXX -- When enabled, this makes it possible to crash trains of others
	     (by building a depot right against a station) */
/*	if (IsTileType(tile, MP_RAILWAY) && (_map5[tile] & 0xFC) == 0xC0)
		return true;*/

	/* Determine the non-diagonal direction in which we will exit this tile */
	t = v->direction >> 1;
	if (!(v->direction & 1) && v->u.rail.track != _state_dir_table[t]) {
		t = (t - 1) & 3;
	}
	/* Calculate next tile */
	tile += TileOffsByDir(t);
	// determine the track status on the next tile.
	ts = GetTileTrackStatus(tile, TRANSPORT_RAIL) & _reachable_tracks[t];

	/* Calc position within the current tile ?? */
	x = v->x_pos & 0xF;
	y = v->y_pos & 0xF;

	switch(v->direction) {
	case 0:
		x = (~x) + (~y) + 24;
		break;
	case 7:
		x = y;
		/* fall through */
	case 1:
		x = (~x) + 16;
		break;
	case 2:
		x = (~x) + y + 8;
		break;
	case 3:
		x = y;
		break;
	case 4:
		x = x + y - 8;
		break;
	case 6:
		x = (~y) + x + 8;
		break;
	}

	if ( (uint16)ts != 0) {
		/* If we approach a rail-piece which we can't enter, don't enter it! */
		if (x + 4 > 15 && !CheckCompatibleRail(v, tile)) {
			v->cur_speed = 0;
			ReverseTrainDirection(v);
			return false;
		}
		if ((ts &= (ts >> 16)) == 0) {
			// make a rail/road crossing red
			if (IsTileType(tile, MP_STREET) && (_map5[tile] & 0xF0) == 0x10) {
				if (!(_map5[tile] & 4)) {
					_map5[tile] |= 4;
					SndPlayVehicleFx(SND_0E_LEVEL_CROSSING, v);
					MarkTileDirtyByTile(tile);
				}
			}
			return true;
		}
	} else if (x + 4 > 15) {
		v->cur_speed = 0;
		ReverseTrainDirection(v);
		return false;
	}

	// slow down
	v->vehstatus |= VS_TRAIN_SLOWING;
	t = _breakdown_speeds[x & 0xF];
	if (!(v->direction&1)) t>>=1;
	if ((uint16)t < v->cur_speed)
		v->cur_speed = t;

	return true;
}

static void TrainLocoHandler(Vehicle *v, bool mode)
{
	int j;

	/* train has crashed? */
	if (v->u.rail.crash_anim_pos != 0) {
		if (!mode) HandleCrashedTrain(v);
		return;
	}

	if (v->u.rail.force_proceed != 0)
		v->u.rail.force_proceed--;

	/* train is broken down? */
	if (v->breakdown_ctr != 0) {
		if (v->breakdown_ctr <= 2) {
			HandleBrokenTrain(v);
			return;
		}
		v->breakdown_ctr--;
	}

	if (HASBIT(v->u.rail.flags, VRF_REVERSING) && v->cur_speed == 0) {
		ReverseTrainDirection(v);
	}

	/* exit if train is stopped */
	if (v->vehstatus & VS_STOPPED && v->cur_speed == 0)
		return;


	if (ProcessTrainOrder(v)) {
		v->load_unload_time_rem = 0;
		v->cur_speed = 0;
		v->subspeed = 0;
		ReverseTrainDirection(v);
		return;
	}

	HandleTrainLoading(v, mode);

	if (v->current_order.type == OT_LOADING)
		return;

	if (CheckTrainStayInDepot(v))
		return;

	if (!mode) HandleLocomotiveSmokeCloud(v);

	j = UpdateTrainSpeed(v);
	if (j == 0) {
		// if the vehicle has speed 0, update the last_speed field.
		if (v->cur_speed != 0)
			return;
	} else {
		TrainCheckIfLineEnds(v);

		do {
			TrainController(v);
			if (v->cur_speed <= 0x100)
				break;
		} while (--j != 0);
	}

	SetLastSpeed(v, v->cur_speed);
}


void Train_Tick(Vehicle *v)
{
	if (_age_cargo_skip_counter == 0 && v->cargo_days != 0xff)
		v->cargo_days++;

	v->tick_counter++;

	if (v->subtype == TS_Front_Engine) {
		TrainLocoHandler(v, false);

		// make sure vehicle wasn't deleted.
		if (v->type == VEH_Train && v->subtype == TS_Front_Engine)
			TrainLocoHandler(v, true);
	} else if (v->subtype == TS_Free_Car && HASBITS(v->vehstatus, VS_CRASHED)) {
		// Delete flooded standalone wagon
		if (++v->u.rail.crash_anim_pos >= 4400)
			DeleteVehicle(v);
	}
}


static const byte _depot_track_ind[4] = {0,1,0,1};

// Validation for the news item "Train is waiting in depot"
static bool ValidateTrainInDepot( uint data_a, uint data_b )
{
	Vehicle *v = GetVehicle(data_a);
	return  (v->u.rail.track == 0x80 && (v->vehstatus | VS_STOPPED));
}

void TrainEnterDepot(Vehicle *v, uint tile)
{
	SetSignalsOnBothDir(tile, _depot_track_ind[_map5[tile]&3]);

	if (v->subtype != TS_Front_Engine)
		v = GetFirstVehicleInChain(v);

	VehicleServiceInDepot(v);

	InvalidateWindow(WC_VEHICLE_DETAILS, v->index);

	v->load_unload_time_rem = 0;
	v->cur_speed = 0;

	MaybeReplaceVehicle(v);

	TriggerVehicle(v, VEHICLE_TRIGGER_DEPOT);

	if (v->current_order.type == OT_GOTO_DEPOT) {
		Order t;

		InvalidateWindow(WC_VEHICLE_VIEW, v->index);

		t = v->current_order;
		v->current_order.type = OT_DUMMY;
		v->current_order.flags = 0;

		if (t.flags & OF_UNLOAD) { // Part of the orderlist?
			v->u.rail.days_since_order_progr = 0;
			v->cur_order_index++;
		} else if (t.flags & OF_FULL_LOAD) { // User initiated?
			v->vehstatus |= VS_STOPPED;
			if (v->owner == _local_player) {
				SetDParam(0, v->unitnumber);
				AddValidatedNewsItem(
					STR_8814_TRAIN_IS_WAITING_IN_DEPOT,
					NEWS_FLAGS(NM_SMALL, NF_VIEWPORT|NF_VEHICLE, NT_ADVICE, 0),
					v->index,
					0,
					ValidateTrainInDepot);
			}
		}
	}
	InvalidateWindowClasses(WC_TRAINS_LIST);
}

static void CheckIfTrainNeedsService(Vehicle *v)
{
	byte depot;
	TrainFindDepotData tfdd;

	if (_patches.servint_trains == 0)
		return;

	if (!VehicleNeedsService(v))
		return;

	if (v->vehstatus & VS_STOPPED)
		return;

	if (_patches.gotodepot && VehicleHasDepotOrders(v))
		return;

	// Don't interfere with a depot visit scheduled by the user, or a
	// depot visit by the order list.
	if (v->current_order.type == OT_GOTO_DEPOT &&
			(v->current_order.flags & (OF_FULL_LOAD | OF_UNLOAD)) != 0)
		return;

	tfdd = FindClosestTrainDepot(v);
	/* Only go to the depot if it is not too far out of our way. */
	if (tfdd.best_length == (uint)-1 || tfdd.best_length > 16 ) {
		if (v->current_order.type == OT_GOTO_DEPOT) {
			/* If we were already heading for a depot but it has
			 * suddenly moved farther away, we continue our normal
			 * schedule? */
			v->current_order.type = OT_DUMMY;
			v->current_order.flags = 0;
			InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, STATUS_BAR);
		}
		return;
	}

	depot = GetDepotByTile(tfdd.tile);

	if (v->current_order.type == OT_GOTO_DEPOT &&
			v->current_order.station != depot &&
			!CHANCE16(3,16))
		return;

	v->current_order.type = OT_GOTO_DEPOT;
	v->current_order.flags = OF_NON_STOP;
	v->current_order.station = depot;
	v->dest_tile = tfdd.tile;
	InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, STATUS_BAR);
}

int32 GetTrainRunningCost(Vehicle *v)
{
	int32 cost = 0;

	do {
		const RailVehicleInfo *rvi = RailVehInfo(v->engine_type);
		if (rvi->running_cost_base)
			cost += rvi->running_cost_base * _price.running_rail[rvi->engclass];
	} while ( (v=v->next) != NULL );

	return cost;
}

void OnNewDay_Train(Vehicle *v)
{
	TileIndex tile;

	if ((++v->day_counter & 7) == 0)
		DecreaseVehicleValue(v);

	if (v->subtype == TS_Front_Engine) {
		CheckVehicleBreakdown(v);
		AgeVehicle(v);

		CheckIfTrainNeedsService(v);

		// check if train hasn't advanced in its order list for a set number of days
		if (_patches.lost_train_days && v->num_orders && !(v->vehstatus & (VS_STOPPED | VS_CRASHED) ) && ++v->u.rail.days_since_order_progr >= _patches.lost_train_days && v->owner == _local_player) {
			v->u.rail.days_since_order_progr = 0;
			SetDParam(0, v->unitnumber);
			AddNewsItem(
				STR_TRAIN_IS_LOST,
				NEWS_FLAGS(NM_SMALL, NF_VIEWPORT|NF_VEHICLE, NT_ADVICE, 0),
				v->index,
				0);
		}

		CheckOrders(v->index, OC_INIT);

		/* update destination */
		if (v->current_order.type == OT_GOTO_STATION &&
				(tile = GetStation(v->current_order.station)->train_tile) != 0)
					v->dest_tile = tile;

		if ((v->vehstatus & VS_STOPPED) == 0) {
			/* running costs */
			int32 cost = GetTrainRunningCost(v) / 364;

			v->profit_this_year -= cost >> 8;

			SET_EXPENSES_TYPE(EXPENSES_TRAIN_RUN);
			SubtractMoneyFromPlayerFract(v->owner, cost);

			InvalidateWindow(WC_VEHICLE_DETAILS, v->index);
			InvalidateWindowClasses(WC_TRAINS_LIST);
		}
	}
}

void TrainsYearlyLoop(void)
{
	Vehicle *v;

	FOR_ALL_VEHICLES(v) {
		if (v->type == VEH_Train && v->subtype == TS_Front_Engine) {

			// show warning if train is not generating enough income last 2 years (corresponds to a red icon in the vehicle list)
			if (_patches.train_income_warn && v->owner == _local_player && v->age >= 730 && v->profit_this_year < 0) {
				SetDParam(1, v->profit_this_year);
				SetDParam(0, v->unitnumber);
				AddNewsItem(
					STR_TRAIN_IS_UNPROFITABLE,
					NEWS_FLAGS(NM_SMALL, NF_VIEWPORT|NF_VEHICLE, NT_ADVICE, 0),
					v->index,
					0);
			}

			v->profit_last_year = v->profit_this_year;
			v->profit_this_year = 0;
			InvalidateWindow(WC_VEHICLE_DETAILS, v->index);
		}
	}
}

extern void ShowTrainViewWindow(Vehicle *v);

void HandleClickOnTrain(Vehicle *v)
{
	if (v->subtype != TS_Front_Engine) v = GetFirstVehicleInChain(v);
	ShowTrainViewWindow(v);
}

void InitializeTrains(void)
{
	_age_cargo_skip_counter = 1;
}