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(svn r3329) - Doc: Some documentation cleanups.

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- Add: TracksOverlap() (from the map branch), TrackdirBitsToTrackBits(), DiagdirReachesTrackdirs(), DiagdirReachesTracks().
 - Fix: Infinite loop in the pathfinder introduces in r3321.
This commit is contained in:
matthijs
2005-12-21 13:53:44 +00:00
parent be01586049
commit 128317d3ec
2 changed files with 76 additions and 21 deletions
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39
pathfind.c
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@@ -585,6 +585,13 @@ static bool NtpVisit(NewTrackPathFinder *tpf, TileIndex tile, uint dir, uint len
return true;
}
/**
* Checks if the shortest path to the given tile/dir so far is still the given
* length.
* @return true if the length is still the same
* @pre The given tile/dir combination should be present in the hash, by a
* previous call to NtpVisit().
*/
static bool NtpCheck(NewTrackPathFinder *tpf, TileIndex tile, uint dir, uint length)
{
uint hash,head,offs;
@@ -666,7 +673,9 @@ static const byte _length_of_track[16] = {
static void NTPEnum(NewTrackPathFinder *tpf, TileIndex tile, uint direction)
{
uint bits, tile_org, track;
TrackBits bits, allbits;
uint track;
TileIndex tile_org;
StackedItem si;
FindLengthOfTunnelResult flotr;
int estimation;
@@ -745,8 +754,7 @@ start_at:
bits = (bits | (bits >> 8)) & 0x3F;
// Check that the tile contains exactly one track
if (bits == 0 || KILL_FIRST_BIT(bits) != 0)
break;
if (bits == 0 || KILL_FIRST_BIT(bits) != 0) break;
///////////////////
// If we reach here, the tile has exactly one track.
@@ -759,16 +767,18 @@ start_at:
goto callback_and_continue;
}
// Regular rail tile, determine which tracks exist.
bits = _m[tile].m5 & _bits_mask[direction];
/* Regular rail tile, determine which tracks exist. */
allbits = _m[tile].m5 & TRACK_BIT_MASK;
/* Which tracks are reachable? */
bits = allbits & DiagdirReachesTracks(direction);
// The tile has no reachable tracks, or
// does the tile contain more than one track?
if (bits == 0 || KILL_FIRST_BIT(bits) != 0)
break;
/* The tile has no reachable tracks => End of rail segment
* or Intersection => End of rail segment. We check this agains all the
* bits, not just reachable ones, to prevent infinite loops. */
if (bits == 0 || TracksOverlap(allbits)) break;
// If we reach here, the tile has exactly one track, and this
// track is reachable.
/* If we reach here, the tile has exactly one track, and this
track is reachable => Rail segment continues */
track = _new_track[FIND_FIRST_BIT(bits)][direction];
assert(track != 0xff);
@@ -788,7 +798,7 @@ start_at:
m3 = _m[tile].m3;
if (!(m3 & SignalAlongTrackdir(track))) {
// if one way signal not pointing towards us, stop going in this direction.
// if one way signal not pointing towards us, stop going in this direction => End of rail segment.
if (m3 & SignalAgainstTrackdir(track)) {
bits = 0;
break;
@@ -800,7 +810,7 @@ start_at:
// reached a red signal.
if (m3 & SignalAgainstTrackdir(track)) {
// two way red signal. unless we passed another green signal on the way,
// stop going in this direction.
// stop going in this direction => End of rail segment.
// this is to prevent us from going into a full platform.
if (!(si.state&1)) {
bits = 0;
@@ -819,7 +829,7 @@ start_at:
}
if (tpf->enum_proc(tile, tpf->userdata, si.first_track, si.cur_length))
return;
return; /* Don't process this tile any further */
}
// continue with the next track
@@ -864,6 +874,7 @@ start_at:
si.tile = tile;
do {
si.track = _new_track[FIND_FIRST_BIT(bits)][direction];
assert(si.track != 0xFF);
si.priority = si.cur_length + estimation;
// out of stack items, bail out?