(svn r11383) -Codechange: fixed all the mess around KillFirstBit (tnx to Rubidium and skidd13)

src/macros.h

@@ -354,7 +354,7 @@ template<typename T> static inline T TOGGLEBIT(T& x, const uint8 y)
  */
 #define IS_CUSTOM_SPRITE(sprite) ((sprite) >= SPR_SIGNALS_BASE)
 
-extern const byte _ffb_64[128];
+extern const byte _ffb_64[64];
 
 /**
  * Returns the first occure of a bit in a 6-bit value (from right).
@@ -368,17 +368,6 @@ extern const byte _ffb_64[128];
  */
 #define FIND_FIRST_BIT(x) _ffb_64[(x)]
 
-/**
- * Returns a value with the first occured of a bit set to zero.
- *
- * Returns x with the first bit from LSB that is not zero set
- * to zero. So, 110100 returns 110000, 000001 returns 000000, etc.
- *
- * @param x The value to returned a new value
- * @return The value which the first bit is set to zero
- */
-#define KILL_FIRST_BIT(x) _ffb_64[(x) + 64]
-
 /**
  * Finds the position of the first bit in an integer.
  *
@@ -416,14 +405,15 @@ Faster ( or at least cleaner ) implementation below?
  * Clear the first bit in an integer.
  *
  * This function returns a value where the first bit (from LSB)
- * is cleared. This function checks only the bits of 0x3F3F!
+ * is cleared.
+ * So, 110100 returns 110000, 000001 returns 000000, etc.
  *
  * @param value The value to clear the first bit
  * @return The new value with the first bit cleared
  */
-static inline uint KillFirstBit2x64(uint value)
+template<typename T> static inline T KillFirstBit(T value)
 {
-	return value &= (uint)(value - 1) | 0x3FFFC0C0;
+	return value &= (T)(value - 1);
 }
 
 /**

src/pathfind.cpp

@@ -234,7 +234,7 @@ static uint SkipToEndOfTunnel(TrackPathFinder* tpf, TileIndex tile, DiagDirectio
 	return flotr.tile;
 }
 
-const byte _ffb_64[128] = {
+const byte _ffb_64[64] = {
  0,  0,  1,  0,  2,  0,  1,  0,
  3,  0,  1,  0,  2,  0,  1,  0,
  4,  0,  1,  0,  2,  0,  1,  0,
@@ -243,15 +243,6 @@ const byte _ffb_64[128] = {
  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,
 };
 
 static void TPFMode1(TrackPathFinder* tpf, TileIndex tile, DiagDirection direction);
@@ -307,10 +298,10 @@ static inline void TPFMode1_NormalCase(TrackPathFinder* tpf, TileIndex tile, Til
 	bits &= 0xBF;
 
 	if (bits != 0) {
-		if (!tpf->disable_tile_hash || (tpf->rd.cur_length <= 64 && (KILL_FIRST_BIT(bits) == 0 || ++tpf->rd.depth <= 7))) {
+		if (!tpf->disable_tile_hash || (tpf->rd.cur_length <= 64 && (KillFirstBit(bits) == 0 || ++tpf->rd.depth <= 7))) {
 			do {
 				int i = FIND_FIRST_BIT(bits);
-				bits = KILL_FIRST_BIT(bits);
+				bits = KillFirstBit(bits);
 
 				tpf->the_dir = (Trackdir)((_otherdir_mask[direction] & (byte)(1 << i)) ? (i + 8) : i);
 				RememberData rd = tpf->rd;
@@ -391,7 +382,7 @@ static void TPFMode1(TrackPathFinder* tpf, TileIndex tile, DiagDirection directi
 
 	do {
 		uint i = FIND_FIRST_BIT(bits);
-		bits = KILL_FIRST_BIT(bits);
+		bits = KillFirstBit(bits);
 
 		tpf->the_dir = (Trackdir)((_otherdir_mask[direction] & (byte)(1 << i)) ? (i + 8) : i);
 		RememberData rd = tpf->rd;
@@ -803,7 +794,7 @@ start_at:
 				bits = TrackdirBitsToTrackBits((TrackdirBits)(ts & TRACKDIR_BIT_MASK));
 
 				/* Check that the tile contains exactly one track */
-				if (bits == 0 || KILL_FIRST_BIT(bits) != 0) break;
+				if (bits == 0 || KillFirstBit(bits) != 0) break;
 
 				if (!HASBIT(tpf->railtypes, GetRailType(tile))) {
 					bits = TRACK_BIT_NONE;

src/rail.h

@@ -370,7 +370,7 @@ static inline Track FindFirstTrack(TrackBits tracks)
  */
 static inline Track TrackBitsToTrack(TrackBits tracks)
 {
-	assert(tracks == INVALID_TRACK_BIT || (tracks != TRACK_BIT_NONE && KILL_FIRST_BIT(tracks & TRACK_BIT_MASK) == 0));
+	assert(tracks == INVALID_TRACK_BIT || (tracks != TRACK_BIT_NONE && KillFirstBit(tracks & TRACK_BIT_MASK) == TRACK_BIT_NONE));
 	return tracks != INVALID_TRACK_BIT ? (Track)FIND_FIRST_BIT(tracks & TRACK_BIT_MASK) : INVALID_TRACK;
 }
 
@@ -785,7 +785,7 @@ static inline bool HasPowerOnRail(RailType enginetype, RailType tiletype)
 static inline bool TracksOverlap(TrackBits bits)
 {
 	/* With no, or only one track, there is no overlap */
-	if (bits == 0 || KILL_FIRST_BIT(bits) == 0) return false;
+	if (bits == TRACK_BIT_NONE || KillFirstBit(bits) == TRACK_BIT_NONE) return false;
 	/* We know that there are at least two tracks present. When there are more
 	 * than 2 tracks, they will surely overlap. When there are two, they will
 	 * always overlap unless they are lower & upper or right & left. */

src/rail_cmd.cpp

@@ -802,7 +802,7 @@ CommandCost CmdBuildSingleSignal(TileIndex tile, uint32 flags, uint32 p1, uint32
 	{
 		/* See if this is a valid track combination for signals, (ie, no overlap) */
 		TrackBits trackbits = GetTrackBits(tile);
-		if (KILL_FIRST_BIT(trackbits) != 0 && /* More than one track present */
+		if (KillFirstBit(trackbits) != TRACK_BIT_NONE && /* More than one track present */
 				trackbits != TRACK_BIT_HORZ &&
 				trackbits != TRACK_BIT_VERT) {
 			return CMD_ERROR;

src/roadveh_cmd.cpp

@@ -1211,7 +1211,7 @@ static Trackdir RoadFindPathToDest(Vehicle* v, TileIndex tile, DiagDirection ent
 	}
 
 	/* Only one track to choose between? */
-	if (!(KillFirstBit2x64(trackdirs))) {
+	if (KillFirstBit(trackdirs) != TRACKDIR_BIT_NONE) {
 		return_track(FindFirstBit2x64(trackdirs));
 	}
 

src/train_cmd.cpp

@@ -2188,10 +2188,10 @@ static Track ChooseTrainTrack(Vehicle* v, TileIndex tile, DiagDirection enterdir
 	TIC()
 #endif
 
-	assert((tracks & ~0x3F) == 0);
+	assert((tracks & ~TRACK_BIT_MASK) == 0);
 
 	/* quick return in case only one possible track is available */
-	if (KILL_FIRST_BIT(tracks) == 0) return FindFirstTrack(tracks);
+	if (KillFirstBit(tracks) == TRACK_BIT_NONE) return FindFirstTrack(tracks);
 
 	if (_patches.yapf.rail_use_yapf) {
 		Trackdir trackdir = YapfChooseRailTrack(v, tile, enterdir, tracks, &path_not_found);

src/yapf/yapf_base.hpp

@@ -192,8 +192,8 @@ public:
 	/** add multiple nodes - direct children of the given node */
 	FORCEINLINE void AddMultipleNodes(Node* parent, const TrackFollower &tf)
 	{
-		bool is_choice = (KillFirstBit2x64(tf.m_new_td_bits) != 0);
-		for (TrackdirBits rtds = tf.m_new_td_bits; rtds != TRACKDIR_BIT_NONE; rtds = (TrackdirBits)KillFirstBit2x64(rtds)) {
+		bool is_choice = (KillFirstBit(tf.m_new_td_bits) != TRACKDIR_BIT_NONE);
+		for (TrackdirBits rtds = tf.m_new_td_bits; rtds != TRACKDIR_BIT_NONE; rtds = KillFirstBit(rtds)) {
 			Trackdir td = (Trackdir)FindFirstBit2x64(rtds);
 			Node& n = Yapf().CreateNewNode();
 			n.Set(parent, tf.m_new_tile, td, is_choice);

src/yapf/yapf_common.hpp

@@ -32,8 +32,8 @@ public:
 	/// Called when YAPF needs to place origin nodes into open list
 	void PfSetStartupNodes()
 	{
-		bool is_choice = (KillFirstBit2x64(m_orgTrackdirs) != 0);
-		for (TrackdirBits tdb = m_orgTrackdirs; tdb != TRACKDIR_BIT_NONE; tdb = (TrackdirBits)KillFirstBit2x64(tdb)) {
+		bool is_choice = (KillFirstBit(m_orgTrackdirs) != TRACKDIR_BIT_NONE);
+		for (TrackdirBits tdb = m_orgTrackdirs; tdb != TRACKDIR_BIT_NONE; tdb = KillFirstBit(tdb)) {
 			Trackdir td = (Trackdir)FindFirstBit2x64(tdb);
 			Node& n1 = Yapf().CreateNewNode();
 			n1.Set(NULL, m_orgTile, td, is_choice);

src/yapf/yapf_costrail.hpp

@@ -387,7 +387,7 @@ no_entry_cost: // jump here at the beginning if the node has no parent (it is th
 			}
 
 			/* Check if the next tile is not a choice. */
-			if (KillFirstBit2x64(tf_local.m_new_td_bits) != 0) {
+			if (KillFirstBit(tf_local.m_new_td_bits) != TRACKDIR_BIT_NONE) {
 				/* More than one segment will follow. Close this one. */
 				end_segment_reason |= ESRB_CHOICE_FOLLOWS;
 				break;

src/yapf/yapf_road.cpp

@@ -97,7 +97,7 @@ public:
 			if (!F.Follow(tile, trackdir)) break;
 
 			// if there are more trackdirs available & reachable, we are at the end of segment
-			if (KillFirstBit2x64(F.m_new_td_bits) != 0) break;
+			if (KillFirstBit(F.m_new_td_bits) != TRACKDIR_BIT_NONE) break;
 
 			Trackdir new_td = (Trackdir)FindFirstBit2x64(F.m_new_td_bits);