X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=3082f56911680242678158b046df3e991e691e82;hp=348feecf70bf5e170211460a23145a55749610dd;hb=98352a5e84096c906d5ecc1aeb2fca8745e173c2;hpb=324ca87affc4959f7017e83437fb06b6e770449c

diff --git a/src/endgame.cpp b/src/endgame.cpp
index 348feecf..3082f569 100644
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -17,26 +17,22 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-
-////
-//// Includes
-////
-
 #include <cassert>
+#include <algorithm>
 
 #include "bitcount.h"
 #include "endgame.h"
+#include "pawns.h"
 
+using std::string;
 
-////
-//// Local definitions
-////
+extern uint32_t probe_kpk_bitbase(Square wksq, Square wpsq, Square bksq, Color stm);
 
 namespace {
 
   // Table used to drive the defending king towards the edge of the board
   // in KX vs K and KQ vs KR endgames.
-  const uint8_t MateTable[64] = {
+  const int MateTable[64] = {
     100, 90, 80, 70, 70, 80, 90, 100,
      90, 70, 60, 50, 50, 60, 70,  90,
      80, 60, 40, 30, 30, 40, 60,  80,
@@ -49,7 +45,7 @@ namespace {
 
   // Table used to drive the defending king towards a corner square of the
   // right color in KBN vs K endgames.
-  const uint8_t KBNKMateTable[64] = {
+  const int KBNKMateTable[64] = {
     200, 190, 180, 170, 160, 150, 140, 130,
     190, 180, 170, 160, 150, 140, 130, 140,
     180, 170, 155, 140, 140, 125, 140, 150,
@@ -68,43 +64,80 @@ namespace {
   // and knight in KR vs KN endgames.
   const int KRKNKingKnightDistancePenalty[8] = { 0, 0, 4, 10, 20, 32, 48, 70 };
 
-  // Bitbase for KP vs K
-  uint8_t KPKBitbase[24576];
+  // Build corresponding key code for the opposite color: "KBPKN" -> "KNKBP"
+  const string swap_colors(const string& keyCode) {
 
-  // Various inline functions for accessing the above arrays
-  inline Value mate_table(Square s) {
-    return Value(MateTable[s]);
+    size_t idx = keyCode.find('K', 1);
+    return keyCode.substr(idx) + keyCode.substr(0, idx);
   }
 
-  inline Value kbnk_mate_table(Square s) {
-    return Value(KBNKMateTable[s]);
-  }
+  // Get the material key of a position out of the given endgame key code
+  // like "KBPKN". The trick here is to first build up a FEN string and then
+  // let a Position object to do the work for us. Note that the FEN string
+  // could correspond to an illegal position.
+  Key mat_key(const string& keyCode) {
 
-  inline Value distance_bonus(int d) {
-    return Value(DistanceBonus[d]);
-  }
+    assert(keyCode.length() > 0 && keyCode.length() < 8);
+    assert(keyCode[0] == 'K');
+
+    string fen;
+    size_t i = 0;
+
+    // First add white and then black pieces
+    do fen += keyCode[i];                while (keyCode[++i] != 'K');
+    do fen += char(tolower(keyCode[i])); while (++i < keyCode.length());
+
+    // Add file padding and remaining empty ranks
+    fen += string(1, '0' + int(8 - keyCode.length())) + "/8/8/8/8/8/8/8 w - - 0 10";
 
-  inline Value krkn_king_knight_distance_penalty(int d) {
-    return Value(KRKNKingKnightDistancePenalty[d]);
+    // Build a Position out of the fen string and get its material key
+    return Position(fen, false, 0).get_material_key();
   }
 
-  // Function for probing the KP vs K bitbase
-  int probe_kpk(Square wksq, Square wpsq, Square bksq, Color stm);
+} // namespace
 
+
+/// Endgames member definitions
+
+template<> const Endgames::M1& Endgames::map<Endgames::M1>() const { return m1; }
+template<> const Endgames::M2& Endgames::map<Endgames::M2>() const { return m2; }
+
+Endgames::Endgames() {
+
+  add<KPK>("KPK");
+  add<KNNK>("KNNK");
+  add<KBNK>("KBNK");
+  add<KRKP>("KRKP");
+  add<KRKB>("KRKB");
+  add<KRKN>("KRKN");
+  add<KQKR>("KQKR");
+  add<KBBKN>("KBBKN");
+
+  add<KNPK>("KNPK");
+  add<KRPKR>("KRPKR");
+  add<KBPKB>("KBPKB");
+  add<KBPKN>("KBPKN");
+  add<KBPPKB>("KBPPKB");
+  add<KRPPKRP>("KRPPKRP");
 }
 
+Endgames::~Endgames() {
 
-////
-//// Functions
-////
+  for (M1::const_iterator it = m1.begin(); it != m1.end(); ++it)
+      delete it->second;
 
-/// init_bitbases() is called during program initialization, and simply loads
-/// bitbases from disk into memory.  At the moment, there is only the bitbase
-/// for KP vs K, but we may decide to add other bitbases later.
-extern void generate_kpk_bitbase(uint8_t bitbase[]);
+  for (M2::const_iterator it = m2.begin(); it != m2.end(); ++it)
+      delete it->second;
+}
 
-void init_bitbases() {
-  generate_kpk_bitbase(KPKBitbase);
+template<EndgameType E>
+void Endgames::add(const string& keyCode) {
+
+  typedef typename eg_family<E>::type T;
+  typedef typename Map<T>::type M;
+
+  const_cast<M&>(map<M>()).insert(std::make_pair(mat_key(keyCode), new Endgame<E>(WHITE)));
+  const_cast<M&>(map<M>()).insert(std::make_pair(mat_key(swap_colors(keyCode)), new Endgame<E>(BLACK)));
 }
 
 
@@ -113,7 +146,7 @@ void init_bitbases() {
 /// attacking side a bonus for driving the defending king towards the edge
 /// of the board, and for keeping the distance between the two kings small.
 template<>
-Value EvaluationFunction<KXK>::apply(const Position& pos) const {
+Value Endgame<KXK>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
   assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO);
@@ -123,8 +156,8 @@ Value EvaluationFunction<KXK>::apply(const Position& pos) const {
 
   Value result =   pos.non_pawn_material(strongerSide)
                  + pos.piece_count(strongerSide, PAWN) * PawnValueEndgame
-                 + mate_table(loserKSq)
-                 + distance_bonus(square_distance(winnerKSq, loserKSq));
+                 + MateTable[loserKSq]
+                 + DistanceBonus[square_distance(winnerKSq, loserKSq)];
 
   if (   pos.piece_count(strongerSide, QUEEN)
       || pos.piece_count(strongerSide, ROOK)
@@ -139,7 +172,7 @@ Value EvaluationFunction<KXK>::apply(const Position& pos) const {
 /// Mate with KBN vs K. This is similar to KX vs K, but we have to drive the
 /// defending king towards a corner square of the right color.
 template<>
-Value EvaluationFunction<KBNK>::apply(const Position& pos) const {
+Value Endgame<KBNK>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
   assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO);
@@ -150,20 +183,20 @@ Value EvaluationFunction<KBNK>::apply(const Position& pos) const {
 
   Square winnerKSq = pos.king_square(strongerSide);
   Square loserKSq = pos.king_square(weakerSide);
-  Square bishopSquare = pos.piece_list(strongerSide, BISHOP, 0);
+  Square bishopSquare = pos.piece_list(strongerSide, BISHOP)[0];
 
   // kbnk_mate_table() tries to drive toward corners A1 or H8,
   // if we have a bishop that cannot reach the above squares we
   // mirror the kings so to drive enemy toward corners A8 or H1.
-  if (opposite_color_squares(bishopSquare, SQ_A1))
+  if (opposite_colors(bishopSquare, SQ_A1))
   {
-      winnerKSq = flop_square(winnerKSq);
-      loserKSq = flop_square(loserKSq);
+      winnerKSq = mirror(winnerKSq);
+      loserKSq = mirror(loserKSq);
   }
 
   Value result =  VALUE_KNOWN_WIN
-                + distance_bonus(square_distance(winnerKSq, loserKSq))
-                + kbnk_mate_table(loserKSq);
+                + DistanceBonus[square_distance(winnerKSq, loserKSq)]
+                + KBNKMateTable[loserKSq];
 
   return strongerSide == pos.side_to_move() ? result : -result;
 }
@@ -171,7 +204,7 @@ Value EvaluationFunction<KBNK>::apply(const Position& pos) const {
 
 /// KP vs K. This endgame is evaluated with the help of a bitbase.
 template<>
-Value EvaluationFunction<KPK>::apply(const Position& pos) const {
+Value Endgame<KPK>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO);
   assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
@@ -185,30 +218,30 @@ Value EvaluationFunction<KPK>::apply(const Position& pos) const {
   {
       wksq = pos.king_square(WHITE);
       bksq = pos.king_square(BLACK);
-      wpsq = pos.piece_list(WHITE, PAWN, 0);
+      wpsq = pos.piece_list(WHITE, PAWN)[0];
       stm = pos.side_to_move();
   }
   else
   {
-      wksq = flip_square(pos.king_square(BLACK));
-      bksq = flip_square(pos.king_square(WHITE));
-      wpsq = flip_square(pos.piece_list(BLACK, PAWN, 0));
-      stm = opposite_color(pos.side_to_move());
+      wksq = flip(pos.king_square(BLACK));
+      bksq = flip(pos.king_square(WHITE));
+      wpsq = flip(pos.piece_list(BLACK, PAWN)[0]);
+      stm = flip(pos.side_to_move());
   }
 
-  if (square_file(wpsq) >= FILE_E)
+  if (file_of(wpsq) >= FILE_E)
   {
-      wksq = flop_square(wksq);
-      bksq = flop_square(bksq);
-      wpsq = flop_square(wpsq);
+      wksq = mirror(wksq);
+      bksq = mirror(bksq);
+      wpsq = mirror(wpsq);
   }
 
-  if (!probe_kpk(wksq, wpsq, bksq, stm))
+  if (!probe_kpk_bitbase(wksq, wpsq, bksq, stm))
       return VALUE_DRAW;
 
   Value result =  VALUE_KNOWN_WIN
                 + PawnValueEndgame
-                + Value(square_rank(wpsq));
+                + Value(rank_of(wpsq));
 
   return strongerSide == pos.side_to_move() ? result : -result;
 }
@@ -219,7 +252,7 @@ Value EvaluationFunction<KPK>::apply(const Position& pos) const {
 /// far advanced with support of the king, while the attacking king is far
 /// away.
 template<>
-Value EvaluationFunction<KRKP>::apply(const Position& pos) const {
+Value Endgame<KRKP>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
   assert(pos.piece_count(strongerSide, PAWN) == 0);
@@ -230,23 +263,23 @@ Value EvaluationFunction<KRKP>::apply(const Position& pos) const {
   int tempo = (pos.side_to_move() == strongerSide);
 
   wksq = pos.king_square(strongerSide);
-  wrsq = pos.piece_list(strongerSide, ROOK, 0);
+  wrsq = pos.piece_list(strongerSide, ROOK)[0];
   bksq = pos.king_square(weakerSide);
-  bpsq = pos.piece_list(weakerSide, PAWN, 0);
+  bpsq = pos.piece_list(weakerSide, PAWN)[0];
 
   if (strongerSide == BLACK)
   {
-      wksq = flip_square(wksq);
-      wrsq = flip_square(wrsq);
-      bksq = flip_square(bksq);
-      bpsq = flip_square(bpsq);
+      wksq = flip(wksq);
+      wrsq = flip(wrsq);
+      bksq = flip(bksq);
+      bpsq = flip(bpsq);
   }
 
-  Square queeningSq = make_square(square_file(bpsq), RANK_1);
+  Square queeningSq = make_square(file_of(bpsq), RANK_1);
   Value result;
 
   // If the stronger side's king is in front of the pawn, it's a win
-  if (wksq < bpsq && square_file(wksq) == square_file(bpsq))
+  if (wksq < bpsq && file_of(wksq) == file_of(bpsq))
       result = RookValueEndgame - Value(square_distance(wksq, bpsq));
 
   // If the weaker side's king is too far from the pawn and the rook,
@@ -257,9 +290,9 @@ Value EvaluationFunction<KRKP>::apply(const Position& pos) const {
 
   // If the pawn is far advanced and supported by the defending king,
   // the position is drawish
-  else if (   square_rank(bksq) <= RANK_3
+  else if (   rank_of(bksq) <= RANK_3
            && square_distance(bksq, bpsq) == 1
-           && square_rank(wksq) >= RANK_4
+           && rank_of(wksq) >= RANK_4
            && square_distance(wksq, bpsq) - tempo > 2)
       result = Value(80 - square_distance(wksq, bpsq) * 8);
 
@@ -276,7 +309,7 @@ Value EvaluationFunction<KRKP>::apply(const Position& pos) const {
 /// KR vs KB. This is very simple, and always returns drawish scores.  The
 /// score is slightly bigger when the defending king is close to the edge.
 template<>
-Value EvaluationFunction<KRKB>::apply(const Position& pos) const {
+Value Endgame<KRKB>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
   assert(pos.piece_count(strongerSide, PAWN) == 0);
@@ -284,7 +317,7 @@ Value EvaluationFunction<KRKB>::apply(const Position& pos) const {
   assert(pos.piece_count(weakerSide, PAWN) == 0);
   assert(pos.piece_count(weakerSide, BISHOP) == 1);
 
-  Value result = mate_table(pos.king_square(weakerSide));
+  Value result = Value(MateTable[pos.king_square(weakerSide)]);
   return strongerSide == pos.side_to_move() ? result : -result;
 }
 
@@ -292,7 +325,7 @@ Value EvaluationFunction<KRKB>::apply(const Position& pos) const {
 /// KR vs KN.  The attacking side has slightly better winning chances than
 /// in KR vs KB, particularly if the king and the knight are far apart.
 template<>
-Value EvaluationFunction<KRKN>::apply(const Position& pos) const {
+Value Endgame<KRKN>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
   assert(pos.piece_count(strongerSide, PAWN) == 0);
@@ -301,12 +334,12 @@ Value EvaluationFunction<KRKN>::apply(const Position& pos) const {
   assert(pos.piece_count(weakerSide, KNIGHT) == 1);
 
   Square defendingKSq = pos.king_square(weakerSide);
-  Square nSq = pos.piece_list(weakerSide, KNIGHT, 0);
+  Square nSq = pos.piece_list(weakerSide, KNIGHT)[0];
 
   int d = square_distance(defendingKSq, nSq);
   Value result =   Value(10)
-                 + mate_table(defendingKSq)
-                 + krkn_king_knight_distance_penalty(d);
+                 + MateTable[defendingKSq]
+                 + KRKNKingKnightDistancePenalty[d];
 
   return strongerSide == pos.side_to_move() ? result : -result;
 }
@@ -318,7 +351,7 @@ Value EvaluationFunction<KRKN>::apply(const Position& pos) const {
 /// for the defending side in the search, this is usually sufficient to be
 /// able to win KQ vs KR.
 template<>
-Value EvaluationFunction<KQKR>::apply(const Position& pos) const {
+Value Endgame<KQKR>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame);
   assert(pos.piece_count(strongerSide, PAWN) == 0);
@@ -330,28 +363,28 @@ Value EvaluationFunction<KQKR>::apply(const Position& pos) const {
 
   Value result =  QueenValueEndgame
                 - RookValueEndgame
-                + mate_table(loserKSq)
-                + distance_bonus(square_distance(winnerKSq, loserKSq));
+                + MateTable[loserKSq]
+                + DistanceBonus[square_distance(winnerKSq, loserKSq)];
 
   return strongerSide == pos.side_to_move() ? result : -result;
 }
 
 template<>
-Value EvaluationFunction<KBBKN>::apply(const Position& pos) const {
+Value Endgame<KBBKN>::operator()(const Position& pos) const {
 
   assert(pos.piece_count(strongerSide, BISHOP) == 2);
   assert(pos.non_pawn_material(strongerSide) == 2*BishopValueMidgame);
   assert(pos.piece_count(weakerSide, KNIGHT) == 1);
   assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame);
-  assert(pos.pieces(PAWN) == EmptyBoardBB);
+  assert(!pos.pieces(PAWN));
 
   Value result = BishopValueEndgame;
   Square wksq = pos.king_square(strongerSide);
   Square bksq = pos.king_square(weakerSide);
-  Square nsq = pos.piece_list(weakerSide, KNIGHT, 0);
+  Square nsq = pos.piece_list(weakerSide, KNIGHT)[0];
 
   // Bonus for attacking king close to defending king
-  result += distance_bonus(square_distance(wksq, bksq));
+  result += Value(DistanceBonus[square_distance(wksq, bksq)]);
 
   // Bonus for driving the defending king and knight apart
   result += Value(square_distance(bksq, nsq) * 32);
@@ -366,12 +399,12 @@ Value EvaluationFunction<KBBKN>::apply(const Position& pos) const {
 /// K and two minors vs K and one or two minors or K and two knights against
 /// king alone are always draw.
 template<>
-Value EvaluationFunction<KmmKm>::apply(const Position&) const {
+Value Endgame<KmmKm>::operator()(const Position&) const {
   return VALUE_DRAW;
 }
 
 template<>
-Value EvaluationFunction<KNNK>::apply(const Position&) const {
+Value Endgame<KNNK>::operator()(const Position&) const {
   return VALUE_DRAW;
 }
 
@@ -381,7 +414,7 @@ Value EvaluationFunction<KNNK>::apply(const Position&) const {
 /// returned. If not, the return value is SCALE_FACTOR_NONE, i.e. no scaling
 /// will be used.
 template<>
-ScaleFactor ScalingFunction<KBPsK>::apply(const Position& pos) const {
+ScaleFactor Endgame<KBPsK>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
   assert(pos.piece_count(strongerSide, BISHOP) == 1);
@@ -391,18 +424,18 @@ ScaleFactor ScalingFunction<KBPsK>::apply(const Position& pos) const {
   // be detected even when the weaker side has some pawns.
 
   Bitboard pawns = pos.pieces(PAWN, strongerSide);
-  File pawnFile = square_file(pos.piece_list(strongerSide, PAWN, 0));
+  File pawnFile = file_of(pos.piece_list(strongerSide, PAWN)[0]);
 
   // All pawns are on a single rook file ?
   if (   (pawnFile == FILE_A || pawnFile == FILE_H)
-      && (pawns & ~file_bb(pawnFile)) == EmptyBoardBB)
+      && !(pawns & ~file_bb(pawnFile)))
   {
-      Square bishopSq = pos.piece_list(strongerSide, BISHOP, 0);
+      Square bishopSq = pos.piece_list(strongerSide, BISHOP)[0];
       Square queeningSq = relative_square(strongerSide, make_square(pawnFile, RANK_8));
       Square kingSq = pos.king_square(weakerSide);
 
-      if (   opposite_color_squares(queeningSq, bishopSq)
-          && file_distance(square_file(kingSq), pawnFile) <= 1)
+      if (   opposite_colors(queeningSq, bishopSq)
+          && abs(file_of(kingSq) - pawnFile) <= 1)
       {
           // The bishop has the wrong color, and the defending king is on the
           // file of the pawn(s) or the neighboring file. Find the rank of the
@@ -410,12 +443,12 @@ ScaleFactor ScalingFunction<KBPsK>::apply(const Position& pos) const {
           Rank rank;
           if (strongerSide == WHITE)
           {
-              for (rank = RANK_7; (rank_bb(rank) & pawns) == EmptyBoardBB; rank--) {}
+              for (rank = RANK_7; !(rank_bb(rank) & pawns); rank--) {}
               assert(rank >= RANK_2 && rank <= RANK_7);
           }
           else
           {
-              for (rank = RANK_2; (rank_bb(rank) & pawns) == EmptyBoardBB; rank++) {}
+              for (rank = RANK_2; !(rank_bb(rank) & pawns); rank++) {}
               rank = Rank(rank ^ 7);  // HACK to get the relative rank
               assert(rank >= RANK_2 && rank <= RANK_7);
           }
@@ -435,7 +468,7 @@ ScaleFactor ScalingFunction<KBPsK>::apply(const Position& pos) const {
 /// It tests for fortress draws with a rook on the third rank defended by
 /// a pawn.
 template<>
-ScaleFactor ScalingFunction<KQKRPs>::apply(const Position& pos) const {
+ScaleFactor Endgame<KQKRPs>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame);
   assert(pos.piece_count(strongerSide, QUEEN) == 1);
@@ -450,7 +483,7 @@ ScaleFactor ScalingFunction<KQKRPs>::apply(const Position& pos) const {
       && (pos.pieces(PAWN, weakerSide) & rank_bb(relative_rank(weakerSide, RANK_2)))
       && (pos.attacks_from<KING>(kingSq) & pos.pieces(PAWN, weakerSide)))
   {
-      Square rsq = pos.piece_list(weakerSide, ROOK, 0);
+      Square rsq = pos.piece_list(weakerSide, ROOK)[0];
       if (pos.attacks_from<PAWN>(rsq, strongerSide) & pos.pieces(PAWN, weakerSide))
           return SCALE_FACTOR_ZERO;
   }
@@ -466,7 +499,7 @@ ScaleFactor ScalingFunction<KQKRPs>::apply(const Position& pos) const {
 /// It would also be nice to rewrite the actual code for this function,
 /// which is mostly copied from Glaurung 1.x, and not very pretty.
 template<>
-ScaleFactor ScalingFunction<KRPKR>::apply(const Position& pos) const {
+ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
   assert(pos.piece_count(strongerSide, PAWN) == 1);
@@ -474,32 +507,32 @@ ScaleFactor ScalingFunction<KRPKR>::apply(const Position& pos) const {
   assert(pos.piece_count(weakerSide, PAWN) == 0);
 
   Square wksq = pos.king_square(strongerSide);
-  Square wrsq = pos.piece_list(strongerSide, ROOK, 0);
-  Square wpsq = pos.piece_list(strongerSide, PAWN, 0);
+  Square wrsq = pos.piece_list(strongerSide, ROOK)[0];
+  Square wpsq = pos.piece_list(strongerSide, PAWN)[0];
   Square bksq = pos.king_square(weakerSide);
-  Square brsq = pos.piece_list(weakerSide, ROOK, 0);
+  Square brsq = pos.piece_list(weakerSide, ROOK)[0];
 
   // Orient the board in such a way that the stronger side is white, and the
   // pawn is on the left half of the board.
   if (strongerSide == BLACK)
   {
-      wksq = flip_square(wksq);
-      wrsq = flip_square(wrsq);
-      wpsq = flip_square(wpsq);
-      bksq = flip_square(bksq);
-      brsq = flip_square(brsq);
+      wksq = flip(wksq);
+      wrsq = flip(wrsq);
+      wpsq = flip(wpsq);
+      bksq = flip(bksq);
+      brsq = flip(brsq);
   }
-  if (square_file(wpsq) > FILE_D)
+  if (file_of(wpsq) > FILE_D)
   {
-      wksq = flop_square(wksq);
-      wrsq = flop_square(wrsq);
-      wpsq = flop_square(wpsq);
-      bksq = flop_square(bksq);
-      brsq = flop_square(brsq);
+      wksq = mirror(wksq);
+      wrsq = mirror(wrsq);
+      wpsq = mirror(wpsq);
+      bksq = mirror(bksq);
+      brsq = mirror(brsq);
   }
 
-  File f = square_file(wpsq);
-  Rank r = square_rank(wpsq);
+  File f = file_of(wpsq);
+  Rank r = rank_of(wpsq);
   Square queeningSq = make_square(f, RANK_8);
   int tempo = (pos.side_to_move() == strongerSide);
 
@@ -508,20 +541,20 @@ ScaleFactor ScalingFunction<KRPKR>::apply(const Position& pos) const {
   if (   r <= RANK_5
       && square_distance(bksq, queeningSq) <= 1
       && wksq <= SQ_H5
-      && (square_rank(brsq) == RANK_6 || (r <= RANK_3 && square_rank(wrsq) != RANK_6)))
+      && (rank_of(brsq) == RANK_6 || (r <= RANK_3 && rank_of(wrsq) != RANK_6)))
       return SCALE_FACTOR_ZERO;
 
   // The defending side saves a draw by checking from behind in case the pawn
   // has advanced to the 6th rank with the king behind.
   if (   r == RANK_6
       && square_distance(bksq, queeningSq) <= 1
-      && square_rank(wksq) + tempo <= RANK_6
-      && (square_rank(brsq) == RANK_1 || (!tempo && abs(square_file(brsq) - f) >= 3)))
+      && rank_of(wksq) + tempo <= RANK_6
+      && (rank_of(brsq) == RANK_1 || (!tempo && abs(file_of(brsq) - f) >= 3)))
       return SCALE_FACTOR_ZERO;
 
   if (   r >= RANK_6
       && bksq == queeningSq
-      && square_rank(brsq) == RANK_1
+      && rank_of(brsq) == RANK_1
       && (!tempo || square_distance(wksq, wpsq) >= 2))
       return SCALE_FACTOR_ZERO;
 
@@ -530,8 +563,8 @@ ScaleFactor ScalingFunction<KRPKR>::apply(const Position& pos) const {
   if (   wpsq == SQ_A7
       && wrsq == SQ_A8
       && (bksq == SQ_H7 || bksq == SQ_G7)
-      && square_file(brsq) == FILE_A
-      && (square_rank(brsq) <= RANK_3 || square_file(wksq) >= FILE_D || square_rank(wksq) <= RANK_5))
+      && file_of(brsq) == FILE_A
+      && (rank_of(brsq) <= RANK_3 || file_of(wksq) >= FILE_D || rank_of(wksq) <= RANK_5))
       return SCALE_FACTOR_ZERO;
 
   // If the defending king blocks the pawn and the attacking king is too far
@@ -547,7 +580,7 @@ ScaleFactor ScalingFunction<KRPKR>::apply(const Position& pos) const {
   // and the defending king cannot gain tempi by threatening the attacking rook.
   if (   r == RANK_7
       && f != FILE_A
-      && square_file(wrsq) == f
+      && file_of(wrsq) == f
       && wrsq != queeningSq
       && (square_distance(wksq, queeningSq) < square_distance(bksq, queeningSq) - 2 + tempo)
       && (square_distance(wksq, queeningSq) < square_distance(bksq, wrsq) + tempo))
@@ -555,7 +588,7 @@ ScaleFactor ScalingFunction<KRPKR>::apply(const Position& pos) const {
 
   // Similar to the above, but with the pawn further back
   if (   f != FILE_A
-      && square_file(wrsq) == f
+      && file_of(wrsq) == f
       && wrsq < wpsq
       && (square_distance(wksq, queeningSq) < square_distance(bksq, queeningSq) - 2 + tempo)
       && (square_distance(wksq, wpsq + DELTA_N) < square_distance(bksq, wpsq + DELTA_N) - 2 + tempo)
@@ -570,9 +603,9 @@ ScaleFactor ScalingFunction<KRPKR>::apply(const Position& pos) const {
   // the pawn's path, it's probably a draw.
   if (r <= RANK_4 && bksq > wpsq)
   {
-      if (square_file(bksq) == square_file(wpsq))
+      if (file_of(bksq) == file_of(wpsq))
           return ScaleFactor(10);
-      if (   abs(square_file(bksq) - square_file(wpsq)) == 1
+      if (   abs(file_of(bksq) - file_of(wpsq)) == 1
           && square_distance(wksq, bksq) > 2)
           return ScaleFactor(24 - 2 * square_distance(wksq, bksq));
   }
@@ -584,15 +617,15 @@ ScaleFactor ScalingFunction<KRPKR>::apply(const Position& pos) const {
 /// single pattern: If the stronger side has no pawns and the defending king
 /// is actively placed, the position is drawish.
 template<>
-ScaleFactor ScalingFunction<KRPPKRP>::apply(const Position& pos) const {
+ScaleFactor Endgame<KRPPKRP>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
   assert(pos.piece_count(strongerSide, PAWN) == 2);
   assert(pos.non_pawn_material(weakerSide) == RookValueMidgame);
   assert(pos.piece_count(weakerSide, PAWN) == 1);
 
-  Square wpsq1 = pos.piece_list(strongerSide, PAWN, 0);
-  Square wpsq2 = pos.piece_list(strongerSide, PAWN, 1);
+  Square wpsq1 = pos.piece_list(strongerSide, PAWN)[0];
+  Square wpsq2 = pos.piece_list(strongerSide, PAWN)[1];
   Square bksq = pos.king_square(weakerSide);
 
   // Does the stronger side have a passed pawn?
@@ -600,7 +633,7 @@ ScaleFactor ScalingFunction<KRPPKRP>::apply(const Position& pos) const {
       || pos.pawn_is_passed(strongerSide, wpsq2))
       return SCALE_FACTOR_NONE;
 
-  Rank r = Max(relative_rank(strongerSide, wpsq1), relative_rank(strongerSide, wpsq2));
+  Rank r = std::max(relative_rank(strongerSide, wpsq1), relative_rank(strongerSide, wpsq2));
 
   if (   file_distance(bksq, wpsq1) <= 1
       && file_distance(bksq, wpsq2) <= 1
@@ -623,7 +656,7 @@ ScaleFactor ScalingFunction<KRPPKRP>::apply(const Position& pos) const {
 /// against king. There is just a single rule here: If all pawns are on
 /// the same rook file and are blocked by the defending king, it's a draw.
 template<>
-ScaleFactor ScalingFunction<KPsK>::apply(const Position& pos) const {
+ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO);
   assert(pos.piece_count(strongerSide, PAWN) >= 2);
@@ -634,21 +667,21 @@ ScaleFactor ScalingFunction<KPsK>::apply(const Position& pos) const {
   Bitboard pawns = pos.pieces(PAWN, strongerSide);
 
   // Are all pawns on the 'a' file?
-  if ((pawns & ~FileABB) == EmptyBoardBB)
+  if (!(pawns & ~FileABB))
   {
       // Does the defending king block the pawns?
       if (   square_distance(ksq, relative_square(strongerSide, SQ_A8)) <= 1
-          || (   square_file(ksq) == FILE_A
-              && (in_front_bb(strongerSide, ksq) & pawns) == EmptyBoardBB))
+          || (   file_of(ksq) == FILE_A
+              && !in_front_bb(strongerSide, ksq) & pawns))
           return SCALE_FACTOR_ZERO;
   }
   // Are all pawns on the 'h' file?
-  else if ((pawns & ~FileHBB) == EmptyBoardBB)
+  else if (!(pawns & ~FileHBB))
   {
     // Does the defending king block the pawns?
     if (   square_distance(ksq, relative_square(strongerSide, SQ_H8)) <= 1
-        || (   square_file(ksq) == FILE_H
-            && (in_front_bb(strongerSide, ksq) & pawns) == EmptyBoardBB))
+        || (   file_of(ksq) == FILE_H
+            && !in_front_bb(strongerSide, ksq) & pawns))
         return SCALE_FACTOR_ZERO;
   }
   return SCALE_FACTOR_NONE;
@@ -661,7 +694,7 @@ ScaleFactor ScalingFunction<KPsK>::apply(const Position& pos) const {
 /// it's a draw. If the two bishops have opposite color, it's almost always
 /// a draw.
 template<>
-ScaleFactor ScalingFunction<KBPKB>::apply(const Position& pos) const {
+ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
   assert(pos.piece_count(strongerSide, BISHOP) == 1);
@@ -670,20 +703,20 @@ ScaleFactor ScalingFunction<KBPKB>::apply(const Position& pos) const {
   assert(pos.piece_count(weakerSide, BISHOP) == 1);
   assert(pos.piece_count(weakerSide, PAWN) == 0);
 
-  Square pawnSq = pos.piece_list(strongerSide, PAWN, 0);
-  Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP, 0);
-  Square weakerBishopSq = pos.piece_list(weakerSide, BISHOP, 0);
+  Square pawnSq = pos.piece_list(strongerSide, PAWN)[0];
+  Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP)[0];
+  Square weakerBishopSq = pos.piece_list(weakerSide, BISHOP)[0];
   Square weakerKingSq = pos.king_square(weakerSide);
 
   // Case 1: Defending king blocks the pawn, and cannot be driven away
-  if (   square_file(weakerKingSq) == square_file(pawnSq)
+  if (   file_of(weakerKingSq) == file_of(pawnSq)
       && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq)
-      && (   opposite_color_squares(weakerKingSq, strongerBishopSq)
+      && (   opposite_colors(weakerKingSq, strongerBishopSq)
           || relative_rank(strongerSide, weakerKingSq) <= RANK_6))
       return SCALE_FACTOR_ZERO;
 
   // Case 2: Opposite colored bishops
-  if (opposite_color_squares(strongerBishopSq, weakerBishopSq))
+  if (opposite_colors(strongerBishopSq, weakerBishopSq))
   {
       // We assume that the position is drawn in the following three situations:
       //
@@ -716,7 +749,7 @@ ScaleFactor ScalingFunction<KBPKB>::apply(const Position& pos) const {
 /// KBPPKBScalingFunction scales KBPP vs KB endgames. It detects a few basic
 /// draws with opposite-colored bishops.
 template<>
-ScaleFactor ScalingFunction<KBPPKB>::apply(const Position& pos) const {
+ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
   assert(pos.piece_count(strongerSide, BISHOP) == 1);
@@ -725,28 +758,28 @@ ScaleFactor ScalingFunction<KBPPKB>::apply(const Position& pos) const {
   assert(pos.piece_count(weakerSide, BISHOP) == 1);
   assert(pos.piece_count(weakerSide, PAWN) == 0);
 
-  Square wbsq = pos.piece_list(strongerSide, BISHOP, 0);
-  Square bbsq = pos.piece_list(weakerSide, BISHOP, 0);
+  Square wbsq = pos.piece_list(strongerSide, BISHOP)[0];
+  Square bbsq = pos.piece_list(weakerSide, BISHOP)[0];
 
-  if (!opposite_color_squares(wbsq, bbsq))
+  if (!opposite_colors(wbsq, bbsq))
       return SCALE_FACTOR_NONE;
 
   Square ksq = pos.king_square(weakerSide);
-  Square psq1 = pos.piece_list(strongerSide, PAWN, 0);
-  Square psq2 = pos.piece_list(strongerSide, PAWN, 1);
-  Rank r1 = square_rank(psq1);
-  Rank r2 = square_rank(psq2);
+  Square psq1 = pos.piece_list(strongerSide, PAWN)[0];
+  Square psq2 = pos.piece_list(strongerSide, PAWN)[1];
+  Rank r1 = rank_of(psq1);
+  Rank r2 = rank_of(psq2);
   Square blockSq1, blockSq2;
 
   if (relative_rank(strongerSide, psq1) > relative_rank(strongerSide, psq2))
   {
       blockSq1 = psq1 + pawn_push(strongerSide);
-      blockSq2 = make_square(square_file(psq2), square_rank(psq1));
+      blockSq2 = make_square(file_of(psq2), rank_of(psq1));
   }
   else
   {
       blockSq1 = psq2 + pawn_push(strongerSide);
-      blockSq2 = make_square(square_file(psq1), square_rank(psq2));
+      blockSq2 = make_square(file_of(psq1), rank_of(psq2));
   }
 
   switch (file_distance(psq1, psq2))
@@ -754,9 +787,9 @@ ScaleFactor ScalingFunction<KBPPKB>::apply(const Position& pos) const {
   case 0:
     // Both pawns are on the same file. Easy draw if defender firmly controls
     // some square in the frontmost pawn's path.
-    if (   square_file(ksq) == square_file(blockSq1)
+    if (   file_of(ksq) == file_of(blockSq1)
         && relative_rank(strongerSide, ksq) >= relative_rank(strongerSide, blockSq1)
-        && opposite_color_squares(ksq, wbsq))
+        && opposite_colors(ksq, wbsq))
         return SCALE_FACTOR_ZERO;
     else
         return SCALE_FACTOR_NONE;
@@ -766,14 +799,14 @@ ScaleFactor ScalingFunction<KBPPKB>::apply(const Position& pos) const {
     // in front of the frontmost pawn's path, and the square diagonally behind
     // this square on the file of the other pawn.
     if (   ksq == blockSq1
-        && opposite_color_squares(ksq, wbsq)
+        && opposite_colors(ksq, wbsq)
         && (   bbsq == blockSq2
             || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(BISHOP, weakerSide))
-            || rank_distance(r1, r2) >= 2))
+            || abs(r1 - r2) >= 2))
         return SCALE_FACTOR_ZERO;
 
     else if (   ksq == blockSq2
-             && opposite_color_squares(ksq, wbsq)
+             && opposite_colors(ksq, wbsq)
              && (   bbsq == blockSq1
                  || (pos.attacks_from<BISHOP>(blockSq1) & pos.pieces(BISHOP, weakerSide))))
         return SCALE_FACTOR_ZERO;
@@ -792,7 +825,7 @@ ScaleFactor ScalingFunction<KBPPKB>::apply(const Position& pos) const {
 /// square of the king is not of the same color as the stronger side's bishop,
 /// it's a draw.
 template<>
-ScaleFactor ScalingFunction<KBPKN>::apply(const Position& pos) const {
+ScaleFactor Endgame<KBPKN>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
   assert(pos.piece_count(strongerSide, BISHOP) == 1);
@@ -801,13 +834,13 @@ ScaleFactor ScalingFunction<KBPKN>::apply(const Position& pos) const {
   assert(pos.piece_count(weakerSide, KNIGHT) == 1);
   assert(pos.piece_count(weakerSide, PAWN) == 0);
 
-  Square pawnSq = pos.piece_list(strongerSide, PAWN, 0);
-  Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP, 0);
+  Square pawnSq = pos.piece_list(strongerSide, PAWN)[0];
+  Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP)[0];
   Square weakerKingSq = pos.king_square(weakerSide);
 
-  if (   square_file(weakerKingSq) == square_file(pawnSq)
+  if (   file_of(weakerKingSq) == file_of(pawnSq)
       && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq)
-      && (   opposite_color_squares(weakerKingSq, strongerBishopSq)
+      && (   opposite_colors(weakerKingSq, strongerBishopSq)
           || relative_rank(strongerSide, weakerKingSq) <= RANK_6))
       return SCALE_FACTOR_ZERO;
 
@@ -819,7 +852,7 @@ ScaleFactor ScalingFunction<KBPKN>::apply(const Position& pos) const {
 /// If the pawn is a rook pawn on the 7th rank and the defending king prevents
 /// the pawn from advancing, the position is drawn.
 template<>
-ScaleFactor ScalingFunction<KNPK>::apply(const Position& pos) const {
+ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame);
   assert(pos.piece_count(strongerSide, KNIGHT) == 1);
@@ -827,7 +860,7 @@ ScaleFactor ScalingFunction<KNPK>::apply(const Position& pos) const {
   assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
   assert(pos.piece_count(weakerSide, PAWN) == 0);
 
-  Square pawnSq = pos.piece_list(strongerSide, PAWN, 0);
+  Square pawnSq = pos.piece_list(strongerSide, PAWN)[0];
   Square weakerKingSq = pos.king_square(weakerSide);
 
   if (   pawnSq == relative_square(strongerSide, SQ_A7)
@@ -849,7 +882,7 @@ ScaleFactor ScalingFunction<KNPK>::apply(const Position& pos) const {
 /// advanced and not on a rook file; in this case it is often possible to win
 /// (e.g. 8/4k3/3p4/3P4/6K1/8/8/8 w - - 0 1).
 template<>
-ScaleFactor ScalingFunction<KPKP>::apply(const Position& pos) const {
+ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO);
   assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
@@ -863,47 +896,31 @@ ScaleFactor ScalingFunction<KPKP>::apply(const Position& pos) const {
   {
       wksq = pos.king_square(WHITE);
       bksq = pos.king_square(BLACK);
-      wpsq = pos.piece_list(WHITE, PAWN, 0);
+      wpsq = pos.piece_list(WHITE, PAWN)[0];
       stm = pos.side_to_move();
   }
   else
   {
-      wksq = flip_square(pos.king_square(BLACK));
-      bksq = flip_square(pos.king_square(WHITE));
-      wpsq = flip_square(pos.piece_list(BLACK, PAWN, 0));
-      stm = opposite_color(pos.side_to_move());
+      wksq = flip(pos.king_square(BLACK));
+      bksq = flip(pos.king_square(WHITE));
+      wpsq = flip(pos.piece_list(BLACK, PAWN)[0]);
+      stm = flip(pos.side_to_move());
   }
 
-  if (square_file(wpsq) >= FILE_E)
+  if (file_of(wpsq) >= FILE_E)
   {
-      wksq = flop_square(wksq);
-      bksq = flop_square(bksq);
-      wpsq = flop_square(wpsq);
+      wksq = mirror(wksq);
+      bksq = mirror(bksq);
+      wpsq = mirror(wpsq);
   }
 
   // If the pawn has advanced to the fifth rank or further, and is not a
   // rook pawn, it's too dangerous to assume that it's at least a draw.
-  if (   square_rank(wpsq) >= RANK_5
-      && square_file(wpsq) != FILE_A)
+  if (   rank_of(wpsq) >= RANK_5
+      && file_of(wpsq) != FILE_A)
       return SCALE_FACTOR_NONE;
 
   // Probe the KPK bitbase with the weakest side's pawn removed. If it's a
   // draw, it's probably at least a draw even with the pawn.
-  return probe_kpk(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_ZERO;
-}
-
-
-namespace {
-
-  // Probe the KP vs K bitbase
-
-  int probe_kpk(Square wksq, Square wpsq, Square bksq, Color stm) {
-
-    int wp = square_file(wpsq) + 4 * (square_rank(wpsq) - 1);
-    int index = int(stm) + 2 * bksq + 128 * wksq + 8192 * wp;
-
-    assert(index >= 0 && index < 24576 * 8);
-
-    return KPKBitbase[index / 8] & (1 << (index & 7));
-  }
+  return probe_kpk_bitbase(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_ZERO;
 }