OpenTTD-patches/pathfind.c

730 lines
19 KiB
C

#include "stdafx.h"
#include "ttd.h"
#include "pathfind.h"
// remember which tiles we have already visited so we don't visit them again.
static bool TPFSetTileBit(TrackPathFinder *tpf, uint tile, int dir)
{
uint hash, val, offs;
TrackPathFinderLink *link, *new_link;
uint bits = 1 << dir;
if (tpf->disable_tile_hash)
return true;
hash = PATHFIND_HASH_TILE(tile);
val = tpf->hash_head[hash];
if (val == 0) {
/* unused hash entry, set the appropriate bit in it and return true
* to indicate that a bit was set. */
tpf->hash_head[hash] = bits;
tpf->hash_tile[hash] = (TileIndex)tile;
return true;
} else if (!(val & 0x8000)) {
/* single tile */
if ( (TileIndex)tile == tpf->hash_tile[hash] ) {
/* found another bit for the same tile,
* check if this bit is already set, if so, return false */
if (val & bits)
return false;
/* otherwise set the bit and return true to indicate that the bit
* was set */
tpf->hash_head[hash] = val | bits;
return true;
} else {
/* two tiles with the same hash, need to make a link */
/* allocate a link. if out of links, handle this by returning
* that a tile was already visisted. */
if (tpf->num_links_left == 0)
return false;
tpf->num_links_left--;
link = tpf->new_link++;
/* move the data that was previously in the hash_??? variables
* to the link struct, and let the hash variables point to the link */
link->tile = tpf->hash_tile[hash];
tpf->hash_tile[hash] = PATHFIND_GET_LINK_OFFS(tpf, link);
link->flags = tpf->hash_head[hash];
tpf->hash_head[hash] = 0xFFFF; /* multi link */
link->next = 0xFFFF;
}
} else {
/* a linked list of many tiles,
* find the one corresponding to the tile, if it exists.
* otherwise make a new link */
offs = tpf->hash_tile[hash];
do {
link = PATHFIND_GET_LINK_PTR(tpf, offs);
if ( (TileIndex)tile == link->tile) {
/* found the tile in the link list,
* check if the bit was alrady set, if so return false to indicate that the
* bit was already set */
if (link->flags & bits)
return false;
link->flags |= bits;
return true;
}
} while ((offs=link->next) != 0xFFFF);
}
/* get here if we need to add a new link to link,
* first, allocate a new link, in the same way as before */
if (tpf->num_links_left == 0)
return false;
tpf->num_links_left--;
new_link = tpf->new_link++;
/* then fill the link with the new info, and establish a ptr from the old
* link to the new one */
new_link->tile = (TileIndex)tile;
new_link->flags = bits;
new_link->next = 0xFFFF;
link->next = PATHFIND_GET_LINK_OFFS(tpf, new_link);
return true;
}
static const byte _bits_mask[4] = {
0x19,
0x16,
0x25,
0x2A,
};
static const byte _tpf_new_direction[14] = {
0,1,0,1,2,1, 0,0,
2,3,3,2,3,0,
};
static const byte _tpf_prev_direction[14] = {
0,1,1,0,1,2, 0,0,
2,3,2,3,0,3,
};
static const byte _otherdir_mask[4] = {
0x10,
0,
0x5,
0x2A,
};
#ifdef DEBUG_TILE_PUSH
extern void dbg_push_tile(uint tile, int track);
extern void dbg_pop_tile();
#endif
void TPFMode2(TrackPathFinder *tpf, uint tile, int direction)
{
uint bits;
int i;
RememberData rd;
// This addition will sometimes overflow by a single tile.
// The use of TILE_MASK here makes sure that we still point at a valid
// tile, and then this tile will be in the sentinel row/col, so GetTileTrackStatus will fail.
tile = TILE_MASK(tile + _tileoffs_by_dir[direction]);
if (++tpf->rd.cur_length > 50)
return;
bits = GetTileTrackStatus(tile, tpf->tracktype);
bits = (byte)((bits | (bits >> 8)) & _bits_mask[direction]);
if (bits == 0)
return;
assert(GET_TILE_X(tile) != 255 && GET_TILE_Y(tile) != 255);
if ( (bits & (bits - 1)) == 0 ) {
/* only one direction */
i = 0;
while (!(bits&1))
i++, bits>>=1;
rd = tpf->rd;
goto continue_here;
}
/* several directions */
i=0;
do {
if (!(bits & 1)) continue;
rd = tpf->rd;
// Change direction 4 times only
if ((byte)i != tpf->rd.pft_var6) {
if(++tpf->rd.depth > 4) {
tpf->rd = rd;
return;
}
tpf->rd.pft_var6 = (byte)i;
}
continue_here:;
tpf->the_dir = HASBIT(_otherdir_mask[direction],i) ? (i+8) : i;
#ifdef DEBUG_TILE_PUSH
dbg_push_tile(tile, tpf->the_dir);
#endif
if (!tpf->enum_proc(tile, tpf->userdata, tpf->the_dir, tpf->rd.cur_length, NULL)) {
TPFMode2(tpf, tile, _tpf_new_direction[tpf->the_dir]);
}
#ifdef DEBUG_TILE_PUSH
dbg_pop_tile();
#endif
tpf->rd = rd;
} while (++i, bits>>=1);
}
static const int8 _get_tunlen_inc[5] = { -16, 0, 16, 0, -16 };
/* Returns the end tile and the length of a tunnel. The length does not
* include the starting tile (entry), it does include the end tile (exit).
*/
FindLengthOfTunnelResult FindLengthOfTunnel(uint tile, int direction)
{
FindLengthOfTunnelResult flotr;
int x,y;
byte z;
flotr.length = 0;
x = GET_TILE_X(tile) * 16;
y = GET_TILE_Y(tile) * 16;
z = GetSlopeZ(x+8, y+8);
for(;;) {
flotr.length++;
x += _get_tunlen_inc[direction];
y += _get_tunlen_inc[direction+1];
tile = TILE_FROM_XY(x,y);
if (IS_TILETYPE(tile, MP_TUNNELBRIDGE) &&
(_map5[tile] & 0xF0) == 0 && // tunnel entrance/exit
//((_map5[tile]>>2)&3) == type && // rail/road-tunnel <-- This is not necesary to check, right?
((_map5[tile] & 3)^2) == direction && // entrance towards: 0 = NE, 1 = SE, 2 = SW, 3 = NW
GetSlopeZ(x+8, y+8) == z)
break;
}
flotr.tile = tile;
return flotr;
}
static const uint16 _tpfmode1_and[4] = { 0x1009, 0x16, 0x520, 0x2A00 };
static uint SkipToEndOfTunnel(TrackPathFinder *tpf, uint tile, int direction) {
FindLengthOfTunnelResult flotr;
TPFSetTileBit(tpf, tile, 14);
flotr = FindLengthOfTunnel(tile, direction);
tpf->rd.cur_length += flotr.length;
TPFSetTileBit(tpf, flotr.tile, 14);
return flotr.tile;
}
const byte _ffb_64[128] = {
0,0,1,0,2,0,1,0,
3,0,1,0,2,0,1,0,
4,0,1,0,2,0,1,0,
3,0,1,0,2,0,1,0,
5,0,1,0,2,0,1,0,
3,0,1,0,2,0,1,0,
4,0,1,0,2,0,1,0,
3,0,1,0,2,0,1,0,
0,0,0,2,0,4,4,6,
0,8,8,10,8,12,12,14,
0,16,16,18,16,20,20,22,
16,24,24,26,24,28,28,30,
0,32,32,34,32,36,36,38,
32,40,40,42,40,44,44,46,
32,48,48,50,48,52,52,54,
48,56,56,58,56,60,60,62,
};
void TPFMode1(TrackPathFinder *tpf, uint tile, int direction)
{
uint bits;
int i;
RememberData rd;
uint tile_org = tile;
if (IS_TILETYPE(tile, MP_TUNNELBRIDGE) && (_map5[tile] & 0xF0)==0) {
if ((_map5[tile] & 3) != direction || ((_map5[tile]>>2)&3) != tpf->tracktype)
return;
tile = SkipToEndOfTunnel(tpf, tile, direction);
}
tile += _tileoffs_by_dir[direction];
tpf->rd.cur_length++;
bits = GetTileTrackStatus(tile, tpf->tracktype);
if ((byte)bits != tpf->var2) {
bits &= _tpfmode1_and[direction];
bits = bits | (bits>>8);
}
bits &= 0xBF;
if (bits != 0) {
if (!tpf->disable_tile_hash || (tpf->rd.cur_length <= 64 && (KILL_FIRST_BIT(bits) == 0 || ++tpf->rd.depth <= 7))) {
do {
i = FIND_FIRST_BIT(bits);
bits = KILL_FIRST_BIT(bits);
tpf->the_dir = (_otherdir_mask[direction] & (byte)(1 << i)) ? (i+8) : i;
rd = tpf->rd;
#ifdef DEBUG_TILE_PUSH
dbg_push_tile(tile, tpf->the_dir);
#endif
if (TPFSetTileBit(tpf, tile, tpf->the_dir) &&
!tpf->enum_proc(tile, tpf->userdata, tpf->the_dir, tpf->rd.cur_length, &tpf->rd.pft_var6) ) {
TPFMode1(tpf, tile, _tpf_new_direction[tpf->the_dir]);
}
#ifdef DEBUG_TILE_PUSH
dbg_pop_tile();
#endif
tpf->rd = rd;
} while (bits != 0);
}
}
/* the next is only used when signals are checked.
* seems to go in 2 directions simultaneously */
/* if i can get rid of this, tail end recursion can be used to minimize
* stack space dramatically. */
if (tpf->hasbit_13)
return;
tile = tile_org;
direction ^= 2;
bits = GetTileTrackStatus(tile, tpf->tracktype);
bits |= (bits >> 8);
if ( (byte)bits != tpf->var2) {
bits &= _bits_mask[direction];
}
bits &= 0xBF;
if (bits == 0)
return;
do {
i = FIND_FIRST_BIT(bits);
bits = KILL_FIRST_BIT(bits);
tpf->the_dir = (_otherdir_mask[direction] & (byte)(1 << i)) ? (i+8) : i;
rd = tpf->rd;
if (TPFSetTileBit(tpf, tile, tpf->the_dir) &&
!tpf->enum_proc(tile, tpf->userdata, tpf->the_dir, tpf->rd.cur_length, &tpf->rd.pft_var6) ) {
TPFMode1(tpf, tile, _tpf_new_direction[tpf->the_dir]);
}
tpf->rd = rd;
} while (bits != 0);
}
void FollowTrack(uint tile, uint16 flags, byte direction, TPFEnumProc *enum_proc, TPFAfterProc *after_proc, void *data)
{
TrackPathFinder tpf;
assert(direction < 4);
/* initialize path finder variables */
tpf.userdata = data;
tpf.enum_proc = enum_proc;
tpf.new_link = tpf.links;
tpf.num_links_left = lengthof(tpf.links);
tpf.rd.cur_length = 0;
tpf.rd.depth = 0;
tpf.rd.pft_var6 = 0;
tpf.var2 = HASBIT(flags, 15) ? 0x43 : 0xFF; /* 0x8000 */
tpf.disable_tile_hash = HASBIT(flags, 12) != 0; /* 0x1000 */
tpf.hasbit_13 = HASBIT(flags, 13) != 0; /* 0x2000 */
tpf.tracktype = (byte)flags;
if (HASBIT(flags, 11)) {
tpf.rd.pft_var6 = 0xFF;
tpf.enum_proc(tile, data, 0, 0, 0);
TPFMode2(&tpf, tile, direction);
} else {
/* clear the hash_heads */
memset(tpf.hash_head, 0, sizeof(tpf.hash_head));
TPFMode1(&tpf, tile, direction);
}
if (after_proc != NULL)
after_proc(&tpf);
}
typedef struct {
TileIndex tile;
uint16 cur_length;
byte track;
byte depth;
byte state;
byte first_track;
} StackedItem;
static const byte _new_dir[6][4] = {
{0,0xff,2,0xff,},
{0xff,1,0xff,3,},
{0xff,0,3,0xff,},
{1,0xff,0xff,2,},
{3,2,0xff,0xff,},
{0xff,0xff,1,0,},
};
static const byte _new_track[6][4] = {
{0,0xff,8,0xff,},
{0xff,1,0xff,9,},
{0xff,2,10,0xff,},
{3,0xff,0xff,11,},
{12,4,0xff,0xff,},
{0xff,0xff,5,13,},
};
typedef struct HashLink {
TileIndex tile;
uint16 typelength;
uint16 next;
} HashLink;
typedef struct {
TPFEnumProc *enum_proc;
void *userdata;
byte tracktype;
uint maxlength;
HashLink *new_link;
uint num_links_left;
int nstack;
StackedItem stack[256]; // priority queue of stacked items
uint16 hash_head[0x400]; // hash heads. 0 means unused. 0xFFC0 = length, 0x3F = type
TileIndex hash_tile[0x400]; // tiles. or links.
HashLink links[0x400]; // hash links
} NewTrackPathFinder;
#define NTP_GET_LINK_OFFS(tpf, link) ((byte*)(link) - (byte*)tpf->links)
#define NTP_GET_LINK_PTR(tpf, link_offs) (HashLink*)((byte*)tpf->links + (link_offs))
#define ARR(i) tpf->stack[(i)-1]
// called after a new element was added in the queue at the last index.
// move it down to the proper position
static void INLINE HeapifyUp(NewTrackPathFinder *tpf)
{
StackedItem si;
int i = ++tpf->nstack;
while (i != 1 && ARR(i).cur_length < ARR(i>>1).cur_length) {
// the child element is larger than the parent item.
// swap the child item and the parent item.
si = ARR(i); ARR(i) = ARR(i>>1); ARR(i>>1) = si;
i>>=1;
}
}
// called after the element 0 was eaten. fill it with a new element
static void INLINE HeapifyDown(NewTrackPathFinder *tpf)
{
StackedItem si;
int i = 1, j;
int n = --tpf->nstack;
if (n == 0) return; // heap is empty so nothing to do?
// copy the last item to index 0. we use it as base for heapify.
ARR(1) = ARR(n+1);
while ((j=i*2) <= n) {
// figure out which is smaller of the children.
if (j != n && ARR(j).cur_length > ARR(j+1).cur_length)
j++; // right item is smaller
assert(i <= n && j <= n);
if (ARR(i).cur_length <= ARR(j).cur_length)
break; // base elem smaller than smallest, done!
// swap parent with the child
si = ARR(i); ARR(i) = ARR(j); ARR(j) = si;
i = j;
}
}
// mark a tile as visited and store the length of the path.
// if we already had a better path to this tile, return false.
// otherwise return true.
static bool NtpVisit(NewTrackPathFinder *tpf, uint tile, uint dir, uint length)
{
uint hash,head;
HashLink *link, *new_link;
assert(length < 1024);
hash = PATHFIND_HASH_TILE(tile);
// never visited before?
if ((head=tpf->hash_head[hash]) == 0) {
tpf->hash_tile[hash] = tile;
tpf->hash_head[hash] = dir | (length << 2);
return true;
}
if (head != 0xffff) {
if ( (TileIndex)tile == tpf->hash_tile[hash] && (head & 0x3) == dir ) {
// longer length
if (length >= (head >> 2)) return false;
tpf->hash_head[hash] = dir | (length << 2);
return true;
}
// two tiles with the same hash, need to make a link
// allocate a link. if out of links, handle this by returning
// that a tile was already visisted.
if (tpf->num_links_left == 0)
return false;
tpf->num_links_left--;
link = tpf->new_link++;
/* move the data that was previously in the hash_??? variables
* to the link struct, and let the hash variables point to the link */
link->tile = tpf->hash_tile[hash];
tpf->hash_tile[hash] = NTP_GET_LINK_OFFS(tpf, link);
link->typelength = tpf->hash_head[hash];
tpf->hash_head[hash] = 0xFFFF; /* multi link */
link->next = 0xFFFF;
} else {
// a linked list of many tiles,
// find the one corresponding to the tile, if it exists.
// otherwise make a new link
uint offs = tpf->hash_tile[hash];
do {
link = NTP_GET_LINK_PTR(tpf, offs);
if ( (TileIndex)tile == link->tile && (uint)(link->typelength & 0x3) == dir) {
if (length >= (uint)(link->typelength >> 2)) return false;
link->typelength = dir | (length << 2);
return true;
}
} while ((offs=link->next) != 0xFFFF);
}
/* get here if we need to add a new link to link,
* first, allocate a new link, in the same way as before */
if (tpf->num_links_left == 0)
return false;
tpf->num_links_left--;
new_link = tpf->new_link++;
/* then fill the link with the new info, and establish a ptr from the old
* link to the new one */
new_link->tile = (TileIndex)tile;
new_link->typelength = dir | (length << 2);
new_link->next = 0xFFFF;
link->next = NTP_GET_LINK_OFFS(tpf, new_link);
return true;
}
static bool NtpCheck(NewTrackPathFinder *tpf, uint tile, uint dir, uint length)
{
uint hash,head,offs;
HashLink *link;
hash = PATHFIND_HASH_TILE(tile);
head=tpf->hash_head[hash];
assert(head);
if (head != 0xffff) {
assert( tpf->hash_tile[hash] == tile && (head & 3) == dir);
assert( (head >> 2) <= length);
return length == (head >> 2);
}
// else it's a linked list of many tiles
offs = tpf->hash_tile[hash];
for(;;) {
link = NTP_GET_LINK_PTR(tpf, offs);
if ( (TileIndex)tile == link->tile && (uint)(link->typelength & 0x3) == dir) {
assert( (uint)(link->typelength >> 2) <= length);
return length == (uint)(link->typelength >> 2);
}
offs = link->next;
assert(offs != 0xffff);
}
}
// new more optimized pathfinder for trains...
void NTPEnum(NewTrackPathFinder *tpf, uint tile, uint direction)
{
uint bits, tile_org;
int i;
StackedItem si;
FindLengthOfTunnelResult flotr;
si.cur_length = 0;
si.depth = 0;
si.state = 0;
restart:
if (IS_TILETYPE(tile, MP_TUNNELBRIDGE) && (_map5[tile] & 0xF0)==0) {
/* This is a tunnel tile */
if ( (uint)(_map5[tile] & 3) != (direction ^ 2)) { /* ^ 2 is reversing the direction */
/* We are not just driving out of the tunnel */
if ( (uint)(_map5[tile] & 3) != direction || ((_map5[tile]>>1)&6) != tpf->tracktype)
/* We are not driving into the tunnel, or it
* is an invalid tunnel */
goto popnext;
flotr = FindLengthOfTunnel(tile, direction);
si.cur_length += flotr.length;
tile = flotr.tile;
}
}
// remember the start tile so we know if we're in an inf loop.
tile_org = tile;
for(;;) {
tile += _tileoffs_by_dir[direction];
// too long search length? bail out.
if (++si.cur_length >= tpf->maxlength)
goto popnext;
// not a regular rail tile?
if (!IS_TILETYPE(tile, MP_RAILWAY) || (bits = _map5[tile]) & 0xC0) {
bits = GetTileTrackStatus(tile, TRANSPORT_RAIL) & _tpfmode1_and[direction];
bits = (bits | (bits >> 8)) & 0x3F;
break;
}
// regular rail tile, determine the tracks that are actually reachable.
bits &= _bits_mask[direction];
if (bits == 0) goto popnext; // no tracks there? stop searching.
// complex tile?, let the generic handler handle that..
if (KILL_FIRST_BIT(bits) != 0) break;
// don't bother calling the callback when we have regular tracks only.
// it's usually not needed anyway. that will speed up things.
direction = _new_dir[FIND_FIRST_BIT(bits)][direction];
assert(direction != 0xFF);
if (tile == tile_org) goto popnext; // detect infinite loop..
}
if (!bits) goto popnext;
// if only one reachable track, use tail recursion optimization.
if (KILL_FIRST_BIT(bits) == 0) {
i = _new_track[FIND_FIRST_BIT(bits)][direction];
// call the callback
if (tpf->enum_proc(tile, tpf->userdata, i, si.cur_length, &si.state))
goto popnext; // we should stop searching in this direction.
// we should continue searching. determine new direction.
direction = _tpf_new_direction[i];
goto restart; // use tail recursion optimization.
}
// too high recursion depth.. bail out..
if (si.depth >= _patches.pf_maxdepth)
goto popnext;
si.depth++; // increase recursion depth.
// see if this tile was already visited..?
if (NtpVisit(tpf, tile, direction, si.cur_length)) {
// push all possible alternatives
si.tile = tile;
do {
si.track = _new_track[FIND_FIRST_BIT(bits)][direction];
// out of stack items, bail out?
if (tpf->nstack >= lengthof(tpf->stack))
break;
tpf->stack[tpf->nstack] = si;
HeapifyUp(tpf);
} while ((bits = KILL_FIRST_BIT(bits)) != 0);
// if this is the first recursion step, we need to fill the first_track member.
// so the code outside knows which path is better.
// also randomize the order in which we search through them.
if (si.depth == 1) {
uint32 r = Random();
assert(tpf->nstack == 2 || tpf->nstack == 3);
if (r&1) swap_byte(&tpf->stack[0].track, &tpf->stack[1].track);
if (tpf->nstack != 2) {
byte t = tpf->stack[2].track;
if (r&2) swap_byte(&tpf->stack[0].track, &t);
if (r&4) swap_byte(&tpf->stack[1].track, &t);
tpf->stack[2].first_track = tpf->stack[2].track = t;
}
tpf->stack[0].first_track = tpf->stack[0].track;
tpf->stack[1].first_track = tpf->stack[1].track;
}
}
popnext:
// where to continue.
do {
if (tpf->nstack == 0) return; // nothing left?
si = tpf->stack[0];
tile = si.tile;
HeapifyDown(tpf);
} while (
!NtpCheck(tpf, tile, _tpf_prev_direction[si.track], si.cur_length) || // already have better path to that tile?
tpf->enum_proc(tile, tpf->userdata, si.track, si.cur_length, &si.state)
);
direction = _tpf_new_direction[si.track];
goto restart;
}
// new pathfinder for trains. better and faster.
void NewTrainPathfind(uint tile, byte direction, TPFEnumProc *enum_proc, void *data, byte *cache)
{
if (!_patches.new_pathfinding) {
FollowTrack(tile, 0x3000 | TRANSPORT_RAIL, direction, enum_proc, NULL, data);
} else {
NewTrackPathFinder tpf;
tpf.userdata = data;
tpf.enum_proc = enum_proc;
tpf.tracktype = 0;
tpf.maxlength = _patches.pf_maxlength;
tpf.nstack = 0;
tpf.new_link = tpf.links;
tpf.num_links_left = lengthof(tpf.links);
memset(tpf.hash_head, 0, sizeof(tpf.hash_head));
NTPEnum(&tpf, tile, direction);
}
}