X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=cc98de90d4f40f71f900c04c1bbc71bd2322ec11;hp=d28772277f2f65af11451e2c6b3c203ee8774fa4;hb=8c2fd2170a0d6dececbe87b0c0353ce718dcd9fd;hpb=c2d42ea8339b49e52a116e488214a14fda09d413

diff --git a/src/endgame.cpp b/src/endgame.cpp
index d2877227..cc98de90 100644
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -17,22 +17,21 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <cassert>
 #include <algorithm>
+#include <cassert>
 
+#include "bitboard.h"
 #include "bitcount.h"
 #include "endgame.h"
-#include "pawns.h"
+#include "movegen.h"
 
 using std::string;
 
-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 int MateTable[64] = {
+  const int MateTable[SQUARE_NB] = {
     100, 90, 80, 70, 70, 80, 90, 100,
      90, 70, 60, 50, 50, 60, 70,  90,
      80, 60, 40, 30, 30, 40, 60,  80,
@@ -45,7 +44,7 @@ namespace {
 
   // Table used to drive the defending king towards a corner square of the
   // right color in KBN vs K endgames.
-  const int KBNKMateTable[64] = {
+  const int KBNKMateTable[SQUARE_NB] = {
     200, 190, 180, 170, 160, 150, 140, 130,
     190, 180, 170, 160, 150, 140, 130, 140,
     180, 170, 155, 140, 140, 125, 140, 150,
@@ -60,56 +59,51 @@ namespace {
   // the two kings in basic endgames.
   const int DistanceBonus[8] = { 0, 0, 100, 80, 60, 40, 20, 10 };
 
-  // Build corresponding key code for the opposite color: "KBPKN" -> "KNKBP"
-  const string swap_colors(const string& keyCode) {
+  // Get the material key of a Position out of the given endgame key code
+  // like "KBPKN". The trick here is to first forge an ad-hoc 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 key(const string& code, Color c) {
 
-    size_t idx = keyCode.find('K', 1);
-    return keyCode.substr(idx) + keyCode.substr(0, idx);
-  }
+    assert(code.length() > 0 && code.length() < 8);
+    assert(code[0] == 'K');
 
-  // 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) {
+    string sides[] = { code.substr(code.find('K', 1)),      // Weaker
+                       code.substr(0, code.find('K', 1)) }; // Stronger
 
-    assert(keyCode.length() > 0 && keyCode.length() < 8);
-    assert(keyCode[0] == 'K');
+    std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower);
 
-    string fen;
-    size_t i = 0;
+    string fen =  sides[0] + char('0' + int(8 - code.length()))
+                + sides[1] + "/8/8/8/8/8/8/8 w - - 0 10";
 
-    // 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";
-
-    // Build a Position out of the fen string and get its material key
-    return Position(fen, false, 0).material_key();
+    return Position(fen, false, NULL).material_key();
   }
 
-} // namespace
+  template<typename M>
+  void delete_endgame(const typename M::value_type& p) { delete p.second; }
 
+} // 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 members definitions
 
 Endgames::Endgames() {
 
+  add<KK>("KK");
   add<KPK>("KPK");
+  add<KBK>("KBK");
+  add<KNK>("KNK");
   add<KNNK>("KNNK");
   add<KBNK>("KBNK");
   add<KRKP>("KRKP");
   add<KRKB>("KRKB");
   add<KRKN>("KRKN");
+  add<KQKP>("KQKP");
   add<KQKR>("KQKR");
   add<KBBKN>("KBBKN");
 
   add<KNPK>("KNPK");
+  add<KNPKB>("KNPKB");
   add<KRPKR>("KRPKR");
   add<KBPKB>("KBPKB");
   add<KBPKN>("KBPKN");
@@ -119,21 +113,15 @@ Endgames::Endgames() {
 
 Endgames::~Endgames() {
 
-  for (M1::const_iterator it = m1.begin(); it != m1.end(); ++it)
-      delete it->second;
-
-  for (M2::const_iterator it = m2.begin(); it != m2.end(); ++it)
-      delete it->second;
+  for_each(m1.begin(), m1.end(), delete_endgame<M1>);
+  for_each(m2.begin(), m2.end(), delete_endgame<M2>);
 }
 
 template<EndgameType E>
-void Endgames::add(const string& keyCode) {
-
-  typedef typename eg_family<E>::type T;
-  typedef typename Map<T>::type M;
+void Endgames::add(const string& code) {
 
-  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)));
+  map((Endgame<E>*)0)[key(code, WHITE)] = new Endgame<E>(WHITE);
+  map((Endgame<E>*)0)[key(code, BLACK)] = new Endgame<E>(BLACK);
 }
 
 
@@ -145,20 +133,24 @@ template<>
 Value Endgame<KXK>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
-  assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO);
+  assert(!pos.count<PAWN>(weakerSide));
+  assert(!pos.checkers()); // Eval is never called when in check
+
+  // Stalemate detection with lone king
+  if (pos.side_to_move() == weakerSide && !MoveList<LEGAL>(pos).size())
+      return VALUE_DRAW;
 
   Square winnerKSq = pos.king_square(strongerSide);
   Square loserKSq = pos.king_square(weakerSide);
 
   Value result =   pos.non_pawn_material(strongerSide)
-                 + pos.piece_count(strongerSide, PAWN) * PawnValueEndgame
+                 + pos.count<PAWN>(strongerSide) * PawnValueEg
                  + MateTable[loserKSq]
                  + DistanceBonus[square_distance(winnerKSq, loserKSq)];
 
-  if (   pos.piece_count(strongerSide, QUEEN)
-      || pos.piece_count(strongerSide, ROOK)
-      || pos.piece_count(strongerSide, BISHOP) > 1)
-      // TODO: check for two equal-colored bishops!
+  if (   pos.count<QUEEN>(strongerSide)
+      || pos.count<ROOK>(strongerSide)
+      || pos.bishop_pair(strongerSide))
       result += VALUE_KNOWN_WIN;
 
   return strongerSide == pos.side_to_move() ? result : -result;
@@ -170,21 +162,21 @@ Value Endgame<KXK>::operator()(const Position& pos) const {
 template<>
 Value Endgame<KBNK>::operator()(const Position& pos) const {
 
+  assert(pos.non_pawn_material(strongerSide) == KnightValueMg + BishopValueMg);
   assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
-  assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO);
-  assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame + BishopValueMidgame);
-  assert(pos.piece_count(strongerSide, BISHOP) == 1);
-  assert(pos.piece_count(strongerSide, KNIGHT) == 1);
-  assert(pos.piece_count(strongerSide, PAWN) == 0);
+  assert(pos.count<BISHOP>(strongerSide) == 1);
+  assert(pos.count<KNIGHT>(strongerSide) == 1);
+  assert(pos.count<  PAWN>(strongerSide) == 0);
+  assert(pos.count<  PAWN>(weakerSide  ) == 0);
 
   Square winnerKSq = pos.king_square(strongerSide);
   Square loserKSq = pos.king_square(weakerSide);
-  Square bishopSquare = pos.piece_list(strongerSide, BISHOP)[0];
+  Square bishopSq = pos.list<BISHOP>(strongerSide)[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_colors(bishopSquare, SQ_A1))
+  if (opposite_colors(bishopSq, SQ_A1))
   {
       winnerKSq = mirror(winnerKSq);
       loserKSq = mirror(loserKSq);
@@ -204,25 +196,25 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO);
   assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
-  assert(pos.piece_count(strongerSide, PAWN) == 1);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
+  assert(pos.count<PAWN>(strongerSide) == 1);
+  assert(pos.count<PAWN>(weakerSide  ) == 0);
 
   Square wksq, bksq, wpsq;
-  Color stm;
+  Color us;
 
   if (strongerSide == WHITE)
   {
       wksq = pos.king_square(WHITE);
       bksq = pos.king_square(BLACK);
-      wpsq = pos.piece_list(WHITE, PAWN)[0];
-      stm = pos.side_to_move();
+      wpsq = pos.list<PAWN>(WHITE)[0];
+      us   = pos.side_to_move();
   }
   else
   {
-      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());
+      wksq = ~pos.king_square(BLACK);
+      bksq = ~pos.king_square(WHITE);
+      wpsq = ~pos.list<PAWN>(BLACK)[0];
+      us   = ~pos.side_to_move();
   }
 
   if (file_of(wpsq) >= FILE_E)
@@ -232,12 +224,10 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
       wpsq = mirror(wpsq);
   }
 
-  if (!probe_kpk_bitbase(wksq, wpsq, bksq, stm))
+  if (!Bitbases::probe_kpk(wksq, wpsq, bksq, us))
       return VALUE_DRAW;
 
-  Value result =  VALUE_KNOWN_WIN
-                + PawnValueEndgame
-                + Value(rank_of(wpsq));
+  Value result = VALUE_KNOWN_WIN + PawnValueEg + Value(rank_of(wpsq));
 
   return strongerSide == pos.side_to_move() ? result : -result;
 }
@@ -250,39 +240,39 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
 template<>
 Value Endgame<KRKP>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
-  assert(pos.piece_count(strongerSide, PAWN) == 0);
+  assert(pos.non_pawn_material(strongerSide) == RookValueMg);
   assert(pos.non_pawn_material(weakerSide) == 0);
-  assert(pos.piece_count(weakerSide, PAWN) == 1);
+  assert(pos.count<PAWN>(strongerSide) == 0);
+  assert(pos.count<PAWN>(weakerSide  ) == 1);
 
   Square wksq, wrsq, bksq, bpsq;
   int tempo = (pos.side_to_move() == strongerSide);
 
   wksq = pos.king_square(strongerSide);
-  wrsq = pos.piece_list(strongerSide, ROOK)[0];
   bksq = pos.king_square(weakerSide);
-  bpsq = pos.piece_list(weakerSide, PAWN)[0];
+  wrsq = pos.list<ROOK>(strongerSide)[0];
+  bpsq = pos.list<PAWN>(weakerSide)[0];
 
   if (strongerSide == BLACK)
   {
-      wksq = flip(wksq);
-      wrsq = flip(wrsq);
-      bksq = flip(bksq);
-      bpsq = flip(bpsq);
+      wksq = ~wksq;
+      wrsq = ~wrsq;
+      bksq = ~bksq;
+      bpsq = ~bpsq;
   }
 
-  Square queeningSq = make_square(file_of(bpsq), RANK_1);
+  Square queeningSq = 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 && file_of(wksq) == file_of(bpsq))
-      result = RookValueEndgame - Value(square_distance(wksq, bpsq));
+      result = RookValueEg - Value(square_distance(wksq, bpsq));
 
   // If the weaker side's king is too far from the pawn and the rook,
   // it's a win
   else if (   square_distance(bksq, bpsq) - (tempo ^ 1) >= 3
            && square_distance(bksq, wrsq) >= 3)
-      result = RookValueEndgame - Value(square_distance(wksq, bpsq));
+      result = RookValueEg - Value(square_distance(wksq, bpsq));
 
   // If the pawn is far advanced and supported by the defending king,
   // the position is drawish
@@ -307,11 +297,11 @@ Value Endgame<KRKP>::operator()(const Position& pos) const {
 template<>
 Value Endgame<KRKB>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
-  assert(pos.piece_count(strongerSide, PAWN) == 0);
-  assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
-  assert(pos.piece_count(weakerSide, BISHOP) == 1);
+  assert(pos.non_pawn_material(strongerSide) == RookValueMg);
+  assert(pos.non_pawn_material(weakerSide  ) == BishopValueMg);
+  assert(pos.count<BISHOP>(weakerSide  ) == 1);
+  assert(pos.count<  PAWN>(weakerSide  ) == 0);
+  assert(pos.count<  PAWN>(strongerSide) == 0);
 
   Value result = Value(MateTable[pos.king_square(weakerSide)]);
   return strongerSide == pos.side_to_move() ? result : -result;
@@ -323,21 +313,52 @@ Value Endgame<KRKB>::operator()(const Position& pos) const {
 template<>
 Value Endgame<KRKN>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
-  assert(pos.piece_count(strongerSide, PAWN) == 0);
-  assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
-  assert(pos.piece_count(weakerSide, KNIGHT) == 1);
+  assert(pos.non_pawn_material(strongerSide) == RookValueMg);
+  assert(pos.non_pawn_material(weakerSide  ) == KnightValueMg);
+  assert(pos.count<KNIGHT>(weakerSide  ) == 1);
+  assert(pos.count<  PAWN>(weakerSide  ) == 0);
+  assert(pos.count<  PAWN>(strongerSide) == 0);
 
   const int penalty[8] = { 0, 10, 14, 20, 30, 42, 58, 80 };
 
   Square bksq = pos.king_square(weakerSide);
-  Square bnsq = pos.piece_list(weakerSide, KNIGHT)[0];
+  Square bnsq = pos.list<KNIGHT>(weakerSide)[0];
   Value result = Value(MateTable[bksq] + penalty[square_distance(bksq, bnsq)]);
   return strongerSide == pos.side_to_move() ? result : -result;
 }
 
 
+/// KQ vs KP.  In general, a win for the stronger side, however, there are a few
+/// important exceptions.  Pawn on 7th rank, A,C,F or H file, with king next can
+/// be a draw, so we scale down to distance between kings only.
+template<>
+Value Endgame<KQKP>::operator()(const Position& pos) const {
+
+  assert(pos.non_pawn_material(strongerSide) == QueenValueMg);
+  assert(pos.non_pawn_material(weakerSide  ) == VALUE_ZERO);
+  assert(pos.count<PAWN>(strongerSide) == 0);
+  assert(pos.count<PAWN>(weakerSide  ) == 1);
+
+  Square winnerKSq = pos.king_square(strongerSide);
+  Square loserKSq = pos.king_square(weakerSide);
+  Square pawnSq = pos.list<PAWN>(weakerSide)[0];
+
+  Value result =  QueenValueEg
+                - PawnValueEg
+                + DistanceBonus[square_distance(winnerKSq, loserKSq)];
+
+  if (   square_distance(loserKSq, pawnSq) == 1
+      && relative_rank(weakerSide, pawnSq) == RANK_7)
+  {
+      File f = file_of(pawnSq);
+
+      if (f == FILE_A || f == FILE_C || f == FILE_F || f == FILE_H)
+          result = Value(DistanceBonus[square_distance(winnerKSq, loserKSq)]);
+  }
+  return strongerSide == pos.side_to_move() ? result : -result;
+}
+
+
 /// KQ vs KR.  This is almost identical to KX vs K:  We give the attacking
 /// king a bonus for having the kings close together, and for forcing the
 /// defending king towards the edge.  If we also take care to avoid null move
@@ -346,16 +367,16 @@ Value Endgame<KRKN>::operator()(const Position& pos) const {
 template<>
 Value Endgame<KQKR>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame);
-  assert(pos.piece_count(strongerSide, PAWN) == 0);
-  assert(pos.non_pawn_material(weakerSide) == RookValueMidgame);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
+  assert(pos.non_pawn_material(strongerSide) == QueenValueMg);
+  assert(pos.non_pawn_material(weakerSide  ) == RookValueMg);
+  assert(pos.count<PAWN>(strongerSide) == 0);
+  assert(pos.count<PAWN>(weakerSide  ) == 0);
 
   Square winnerKSq = pos.king_square(strongerSide);
   Square loserKSq = pos.king_square(weakerSide);
 
-  Value result =  QueenValueEndgame
-                - RookValueEndgame
+  Value result =  QueenValueEg
+                - RookValueEg
                 + MateTable[loserKSq]
                 + DistanceBonus[square_distance(winnerKSq, loserKSq)];
 
@@ -365,16 +386,16 @@ Value Endgame<KQKR>::operator()(const Position& pos) const {
 template<>
 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.non_pawn_material(strongerSide) == 2 * BishopValueMg);
+  assert(pos.non_pawn_material(weakerSide  ) == KnightValueMg);
+  assert(pos.count<BISHOP>(strongerSide) == 2);
+  assert(pos.count<KNIGHT>(weakerSide  ) == 1);
   assert(!pos.pieces(PAWN));
 
-  Value result = BishopValueEndgame;
+  Value result = BishopValueEg;
   Square wksq = pos.king_square(strongerSide);
   Square bksq = pos.king_square(weakerSide);
-  Square nsq = pos.piece_list(weakerSide, KNIGHT)[0];
+  Square nsq = pos.list<KNIGHT>(weakerSide)[0];
 
   // Bonus for attacking king close to defending king
   result += Value(DistanceBonus[square_distance(wksq, bksq)]);
@@ -383,23 +404,19 @@ Value Endgame<KBBKN>::operator()(const Position& pos) const {
   result += Value(square_distance(bksq, nsq) * 32);
 
   // Bonus for restricting the knight's mobility
-  result += Value((8 - count_1s<CNT32_MAX15>(pos.attacks_from<KNIGHT>(nsq))) * 8);
+  result += Value((8 - popcount<Max15>(pos.attacks_from<KNIGHT>(nsq))) * 8);
 
   return strongerSide == pos.side_to_move() ? result : -result;
 }
 
 
-/// K and two minors vs K and one or two minors or K and two knights against
-/// king alone are always draw.
-template<>
-Value Endgame<KmmKm>::operator()(const Position&) const {
-  return VALUE_DRAW;
-}
+/// Some cases of trivial draws
+template<> Value Endgame<KK>::operator()(const Position&) const { return VALUE_DRAW; }
+template<> Value Endgame<KBK>::operator()(const Position&) const { return VALUE_DRAW; }
+template<> Value Endgame<KNK>::operator()(const Position&) const { return VALUE_DRAW; }
+template<> Value Endgame<KNNK>::operator()(const Position&) const { return VALUE_DRAW; }
+template<> Value Endgame<KmmKm>::operator()(const Position&) const { return VALUE_DRAW; }
 
-template<>
-Value Endgame<KNNK>::operator()(const Position&) const {
-  return VALUE_DRAW;
-}
 
 /// K, bishop and one or more pawns vs K. It checks for draws with rook pawns and
 /// a bishop of the wrong color. If such a draw is detected, SCALE_FACTOR_DRAW
@@ -408,29 +425,29 @@ Value Endgame<KNNK>::operator()(const Position&) const {
 template<>
 ScaleFactor Endgame<KBPsK>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
-  assert(pos.piece_count(strongerSide, BISHOP) == 1);
-  assert(pos.piece_count(strongerSide, PAWN) >= 1);
+  assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
+  assert(pos.count<BISHOP>(strongerSide) == 1);
+  assert(pos.count<  PAWN>(strongerSide) >= 1);
 
   // No assertions about the material of weakerSide, because we want draws to
   // be detected even when the weaker side has some pawns.
 
-  Bitboard pawns = pos.pieces(PAWN, strongerSide);
-  File pawnFile = file_of(pos.piece_list(strongerSide, PAWN)[0]);
+  Bitboard pawns = pos.pieces(strongerSide, PAWN);
+  File pawnFile = file_of(pos.list<PAWN>(strongerSide)[0]);
 
   // All pawns are on a single rook file ?
-  if (   (pawnFile == FILE_A || pawnFile == FILE_H)
+  if (    (pawnFile == FILE_A || pawnFile == FILE_H)
       && !(pawns & ~file_bb(pawnFile)))
   {
-      Square bishopSq = pos.piece_list(strongerSide, BISHOP)[0];
-      Square queeningSq = relative_square(strongerSide, make_square(pawnFile, RANK_8));
+      Square bishopSq = pos.list<BISHOP>(strongerSide)[0];
+      Square queeningSq = relative_square(strongerSide, pawnFile | RANK_8);
       Square kingSq = pos.king_square(weakerSide);
 
       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
+          // file of the pawn(s) or the adjacent file. Find the rank of the
           // frontmost pawn.
           Rank rank;
           if (strongerSide == WHITE)
@@ -451,6 +468,29 @@ ScaleFactor Endgame<KBPsK>::operator()(const Position& pos) const {
               return SCALE_FACTOR_DRAW;
       }
   }
+
+  // All pawns on same B or G file? Then potential draw
+  if (    (pawnFile == FILE_B || pawnFile == FILE_G)
+      && !(pos.pieces(PAWN) & ~file_bb(pawnFile))
+      && pos.non_pawn_material(weakerSide) == 0
+      && pos.count<PAWN>(weakerSide) >= 1)
+  {
+      // Get weaker pawn closest to opponent's queening square
+      Bitboard wkPawns = pos.pieces(weakerSide, PAWN);
+      Square weakerPawnSq = strongerSide == WHITE ? msb(wkPawns) : lsb(wkPawns);
+
+      Square strongerKingSq = pos.king_square(strongerSide);
+      Square weakerKingSq = pos.king_square(weakerSide);
+      Square bishopSq = pos.list<BISHOP>(strongerSide)[0];
+
+      // Draw if weaker pawn is on rank 7, bishop can't attack the pawn, and
+      // weaker king can stop opposing opponent's king from penetrating.
+      if (   relative_rank(strongerSide, weakerPawnSq) == RANK_7
+          && opposite_colors(bishopSq, weakerPawnSq)
+          && square_distance(weakerPawnSq, weakerKingSq) <= square_distance(weakerPawnSq, strongerKingSq))
+          return SCALE_FACTOR_DRAW;
+  }
+
   return SCALE_FACTOR_NONE;
 }
 
@@ -460,21 +500,21 @@ ScaleFactor Endgame<KBPsK>::operator()(const Position& pos) const {
 template<>
 ScaleFactor Endgame<KQKRPs>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame);
-  assert(pos.piece_count(strongerSide, QUEEN) == 1);
-  assert(pos.piece_count(strongerSide, PAWN) == 0);
-  assert(pos.piece_count(weakerSide, ROOK) == 1);
-  assert(pos.piece_count(weakerSide, PAWN) >= 1);
+  assert(pos.non_pawn_material(strongerSide) == QueenValueMg);
+  assert(pos.count<QUEEN>(strongerSide) == 1);
+  assert(pos.count< PAWN>(strongerSide) == 0);
+  assert(pos.count< ROOK>(weakerSide  ) == 1);
+  assert(pos.count< PAWN>(weakerSide  ) >= 1);
 
   Square kingSq = pos.king_square(weakerSide);
-  if (   relative_rank(weakerSide, kingSq) <= RANK_2
-      && relative_rank(weakerSide, pos.king_square(strongerSide)) >= RANK_4
-      && (pos.pieces(ROOK, weakerSide) & rank_bb(relative_rank(weakerSide, RANK_3)))
-      && (pos.pieces(PAWN, weakerSide) & rank_bb(relative_rank(weakerSide, RANK_2)))
-      && (pos.attacks_from<KING>(kingSq) & pos.pieces(PAWN, weakerSide)))
+  if (    relative_rank(weakerSide, kingSq) <= RANK_2
+      &&  relative_rank(weakerSide, pos.king_square(strongerSide)) >= RANK_4
+      && (pos.pieces(weakerSide, ROOK) & rank_bb(relative_rank(weakerSide, RANK_3)))
+      && (pos.pieces(weakerSide, PAWN) & rank_bb(relative_rank(weakerSide, RANK_2)))
+      && (pos.attacks_from<KING>(kingSq) & pos.pieces(weakerSide, PAWN)))
   {
-      Square rsq = pos.piece_list(weakerSide, ROOK)[0];
-      if (pos.attacks_from<PAWN>(rsq, strongerSide) & pos.pieces(PAWN, weakerSide))
+      Square rsq = pos.list<ROOK>(weakerSide)[0];
+      if (pos.attacks_from<PAWN>(rsq, strongerSide) & pos.pieces(weakerSide, PAWN))
           return SCALE_FACTOR_DRAW;
   }
   return SCALE_FACTOR_NONE;
@@ -490,26 +530,26 @@ ScaleFactor Endgame<KQKRPs>::operator()(const Position& pos) const {
 template<>
 ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == RookValueMidgame);
-  assert(pos.piece_count(strongerSide, PAWN) == 1);
-  assert(pos.non_pawn_material(weakerSide) == RookValueMidgame);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
+  assert(pos.non_pawn_material(strongerSide) == RookValueMg);
+  assert(pos.non_pawn_material(weakerSide)   == RookValueMg);
+  assert(pos.count<PAWN>(strongerSide) == 1);
+  assert(pos.count<PAWN>(weakerSide  ) == 0);
 
   Square wksq = pos.king_square(strongerSide);
-  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 wrsq = pos.list<ROOK>(strongerSide)[0];
+  Square wpsq = pos.list<PAWN>(strongerSide)[0];
+  Square brsq = pos.list<ROOK>(weakerSide)[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(wksq);
-      wrsq = flip(wrsq);
-      wpsq = flip(wpsq);
-      bksq = flip(bksq);
-      brsq = flip(brsq);
+      wksq = ~wksq;
+      wrsq = ~wrsq;
+      wpsq = ~wpsq;
+      bksq = ~bksq;
+      brsq = ~brsq;
   }
   if (file_of(wpsq) > FILE_D)
   {
@@ -522,7 +562,7 @@ ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
 
   File f = file_of(wpsq);
   Rank r = rank_of(wpsq);
-  Square queeningSq = make_square(f, RANK_8);
+  Square queeningSq = f | RANK_8;
   int tempo = (pos.side_to_move() == strongerSide);
 
   // If the pawn is not too far advanced and the defending king defends the
@@ -608,13 +648,13 @@ ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
 template<>
 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);
+  assert(pos.non_pawn_material(strongerSide) == RookValueMg);
+  assert(pos.non_pawn_material(weakerSide)   == RookValueMg);
+  assert(pos.count<PAWN>(strongerSide) == 2);
+  assert(pos.count<PAWN>(weakerSide  ) == 1);
 
-  Square wpsq1 = pos.piece_list(strongerSide, PAWN)[0];
-  Square wpsq2 = pos.piece_list(strongerSide, PAWN)[1];
+  Square wpsq1 = pos.list<PAWN>(strongerSide)[0];
+  Square wpsq2 = pos.list<PAWN>(strongerSide)[1];
   Square bksq = pos.king_square(weakerSide);
 
   // Does the stronger side have a passed pawn?
@@ -647,20 +687,20 @@ template<>
 ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO);
-  assert(pos.piece_count(strongerSide, PAWN) >= 2);
-  assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
+  assert(pos.non_pawn_material(weakerSide)   == VALUE_ZERO);
+  assert(pos.count<PAWN>(strongerSide) >= 2);
+  assert(pos.count<PAWN>(weakerSide  ) == 0);
 
   Square ksq = pos.king_square(weakerSide);
-  Bitboard pawns = pos.pieces(PAWN, strongerSide);
+  Bitboard pawns = pos.pieces(strongerSide, PAWN);
 
   // Are all pawns on the 'a' file?
   if (!(pawns & ~FileABB))
   {
       // Does the defending king block the pawns?
       if (   square_distance(ksq, relative_square(strongerSide, SQ_A8)) <= 1
-          || (   file_of(ksq) == FILE_A
-              && !in_front_bb(strongerSide, ksq) & pawns))
+          || (    file_of(ksq) == FILE_A
+              && !(in_front_bb(strongerSide, rank_of(ksq)) & pawns)))
           return SCALE_FACTOR_DRAW;
   }
   // Are all pawns on the 'h' file?
@@ -668,8 +708,8 @@ ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
   {
     // Does the defending king block the pawns?
     if (   square_distance(ksq, relative_square(strongerSide, SQ_H8)) <= 1
-        || (   file_of(ksq) == FILE_H
-            && !in_front_bb(strongerSide, ksq) & pawns))
+        || (    file_of(ksq) == FILE_H
+            && !(in_front_bb(strongerSide, rank_of(ksq)) & pawns)))
         return SCALE_FACTOR_DRAW;
   }
   return SCALE_FACTOR_NONE;
@@ -683,16 +723,16 @@ ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
 template<>
 ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
-  assert(pos.piece_count(strongerSide, BISHOP) == 1);
-  assert(pos.piece_count(strongerSide, PAWN) == 1);
-  assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame);
-  assert(pos.piece_count(weakerSide, BISHOP) == 1);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
+  assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
+  assert(pos.non_pawn_material(weakerSide  ) == BishopValueMg);
+  assert(pos.count<BISHOP>(strongerSide) == 1);
+  assert(pos.count<BISHOP>(weakerSide  ) == 1);
+  assert(pos.count<  PAWN>(strongerSide) == 1);
+  assert(pos.count<  PAWN>(weakerSide  ) == 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.list<PAWN>(strongerSide)[0];
+  Square strongerBishopSq = pos.list<BISHOP>(strongerSide)[0];
+  Square weakerBishopSq = pos.list<BISHOP>(weakerSide)[0];
   Square weakerKingSq = pos.king_square(weakerSide);
 
   // Case 1: Defending king blocks the pawn, and cannot be driven away
@@ -719,9 +759,9 @@ ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
           return SCALE_FACTOR_DRAW;
       else
       {
-          Bitboard path = squares_in_front_of(strongerSide, pawnSq);
+          Bitboard path = forward_bb(strongerSide, pawnSq);
 
-          if (path & pos.pieces(KING, weakerSide))
+          if (path & pos.pieces(weakerSide, KING))
               return SCALE_FACTOR_DRAW;
 
           if (  (pos.attacks_from<BISHOP>(weakerBishopSq) & path)
@@ -738,22 +778,22 @@ ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
 template<>
 ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
-  assert(pos.piece_count(strongerSide, BISHOP) == 1);
-  assert(pos.piece_count(strongerSide, PAWN) == 2);
-  assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame);
-  assert(pos.piece_count(weakerSide, BISHOP) == 1);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
+  assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
+  assert(pos.non_pawn_material(weakerSide  ) == BishopValueMg);
+  assert(pos.count<BISHOP>(strongerSide) == 1);
+  assert(pos.count<BISHOP>(weakerSide  ) == 1);
+  assert(pos.count<  PAWN>(strongerSide) == 2);
+  assert(pos.count<  PAWN>(weakerSide  ) == 0);
 
-  Square wbsq = pos.piece_list(strongerSide, BISHOP)[0];
-  Square bbsq = pos.piece_list(weakerSide, BISHOP)[0];
+  Square wbsq = pos.list<BISHOP>(strongerSide)[0];
+  Square bbsq = pos.list<BISHOP>(weakerSide)[0];
 
   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];
+  Square psq1 = pos.list<PAWN>(strongerSide)[0];
+  Square psq2 = pos.list<PAWN>(strongerSide)[1];
   Rank r1 = rank_of(psq1);
   Rank r2 = rank_of(psq2);
   Square blockSq1, blockSq2;
@@ -761,12 +801,12 @@ ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
   if (relative_rank(strongerSide, psq1) > relative_rank(strongerSide, psq2))
   {
       blockSq1 = psq1 + pawn_push(strongerSide);
-      blockSq2 = make_square(file_of(psq2), rank_of(psq1));
+      blockSq2 = file_of(psq2) | rank_of(psq1);
   }
   else
   {
       blockSq1 = psq2 + pawn_push(strongerSide);
-      blockSq2 = make_square(file_of(psq1), rank_of(psq2));
+      blockSq2 = file_of(psq1) | rank_of(psq2);
   }
 
   switch (file_distance(psq1, psq2))
@@ -782,20 +822,20 @@ ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
         return SCALE_FACTOR_NONE;
 
   case 1:
-    // Pawns on neighboring files. Draw if defender firmly controls the square
+    // Pawns on adjacent files. Draw if defender firmly controls the square
     // 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_colors(ksq, wbsq)
         && (   bbsq == blockSq2
-            || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(BISHOP, weakerSide))
+            || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(weakerSide, BISHOP))
             || abs(r1 - r2) >= 2))
         return SCALE_FACTOR_DRAW;
 
     else if (   ksq == blockSq2
              && opposite_colors(ksq, wbsq)
              && (   bbsq == blockSq1
-                 || (pos.attacks_from<BISHOP>(blockSq1) & pos.pieces(BISHOP, weakerSide))))
+                 || (pos.attacks_from<BISHOP>(blockSq1) & pos.pieces(weakerSide, BISHOP))))
         return SCALE_FACTOR_DRAW;
     else
         return SCALE_FACTOR_NONE;
@@ -813,15 +853,15 @@ ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
 template<>
 ScaleFactor Endgame<KBPKN>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame);
-  assert(pos.piece_count(strongerSide, BISHOP) == 1);
-  assert(pos.piece_count(strongerSide, PAWN) == 1);
-  assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame);
-  assert(pos.piece_count(weakerSide, KNIGHT) == 1);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
+  assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
+  assert(pos.non_pawn_material(weakerSide  ) == KnightValueMg);
+  assert(pos.count<BISHOP>(strongerSide) == 1);
+  assert(pos.count<KNIGHT>(weakerSide  ) == 1);
+  assert(pos.count<  PAWN>(strongerSide) == 1);
+  assert(pos.count<  PAWN>(weakerSide  ) == 0);
 
-  Square pawnSq = pos.piece_list(strongerSide, PAWN)[0];
-  Square strongerBishopSq = pos.piece_list(strongerSide, BISHOP)[0];
+  Square pawnSq = pos.list<PAWN>(strongerSide)[0];
+  Square strongerBishopSq = pos.list<BISHOP>(strongerSide)[0];
   Square weakerKingSq = pos.king_square(weakerSide);
 
   if (   file_of(weakerKingSq) == file_of(pawnSq)
@@ -840,13 +880,13 @@ ScaleFactor Endgame<KBPKN>::operator()(const Position& pos) const {
 template<>
 ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
 
-  assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame);
-  assert(pos.piece_count(strongerSide, KNIGHT) == 1);
-  assert(pos.piece_count(strongerSide, PAWN) == 1);
-  assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
-  assert(pos.piece_count(weakerSide, PAWN) == 0);
+  assert(pos.non_pawn_material(strongerSide) == KnightValueMg);
+  assert(pos.non_pawn_material(weakerSide  ) == VALUE_ZERO);
+  assert(pos.count<KNIGHT>(strongerSide) == 1);
+  assert(pos.count<  PAWN>(strongerSide) == 1);
+  assert(pos.count<  PAWN>(weakerSide  ) == 0);
 
-  Square pawnSq = pos.piece_list(strongerSide, PAWN)[0];
+  Square pawnSq = pos.list<PAWN>(strongerSide)[0];
   Square weakerKingSq = pos.king_square(weakerSide);
 
   if (   pawnSq == relative_square(strongerSide, SQ_A7)
@@ -861,6 +901,24 @@ ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
 }
 
 
+/// K, knight and a pawn vs K and bishop. If knight can block bishop from taking
+/// pawn, it's a win. Otherwise, drawn.
+template<>
+ScaleFactor Endgame<KNPKB>::operator()(const Position& pos) const {
+
+  Square pawnSq = pos.list<PAWN>(strongerSide)[0];
+  Square bishopSq = pos.list<BISHOP>(weakerSide)[0];
+  Square weakerKingSq = pos.king_square(weakerSide);
+
+  // King needs to get close to promoting pawn to prevent knight from blocking.
+  // Rules for this are very tricky, so just approximate.
+  if (forward_bb(strongerSide, pawnSq) & pos.attacks_from<BISHOP>(bishopSq))
+      return ScaleFactor(square_distance(weakerKingSq, pawnSq));
+
+  return SCALE_FACTOR_NONE;
+}
+
+
 /// K and a pawn vs K and a pawn. This is done by removing the weakest side's
 /// pawn and probing the KP vs K bitbase: If the weakest side has a draw without
 /// the pawn, she probably has at least a draw with the pawn as well. The exception
@@ -870,21 +928,21 @@ template<>
 ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
 
   assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO);
-  assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
-  assert(pos.piece_count(WHITE, PAWN) == 1);
-  assert(pos.piece_count(BLACK, PAWN) == 1);
+  assert(pos.non_pawn_material(weakerSide  ) == VALUE_ZERO);
+  assert(pos.count<PAWN>(WHITE) == 1);
+  assert(pos.count<PAWN>(BLACK) == 1);
 
   Square wksq = pos.king_square(strongerSide);
   Square bksq = pos.king_square(weakerSide);
-  Square wpsq = pos.piece_list(strongerSide, PAWN)[0];
-  Color stm = pos.side_to_move();
+  Square wpsq = pos.list<PAWN>(strongerSide)[0];
+  Color us = pos.side_to_move();
 
   if (strongerSide == BLACK)
   {
-      wksq = flip(wksq);
-      bksq = flip(bksq);
-      wpsq = flip(wpsq);
-      stm = flip(stm);
+      wksq = ~wksq;
+      bksq = ~bksq;
+      wpsq = ~wpsq;
+      us   = ~us;
   }
 
   if (file_of(wpsq) >= FILE_E)
@@ -902,5 +960,5 @@ ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
 
   // 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_bitbase(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
+  return Bitbases::probe_kpk(wksq, wpsq, bksq, us) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
 }