Stockfish 2.2.2

Dedicated to the new Jim's super fast builds ! :-)

stockfish bench signature is: 5447426

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/benchmark.cpp

@@ -28,7 +28,6 @@
 #include "ucioption.h"
 
 using namespace std;
-using namespace Search;
 
 static const char* Defaults[] = {
   "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
@@ -61,7 +60,7 @@ static const char* Defaults[] = {
 void benchmark(int argc, char* argv[]) {
 
   vector<string> fens;
-  LimitsType limits;
+  Search::LimitsType limits;
   int time;
   int64_t nodes = 0;
 
@@ -115,14 +114,14 @@ void benchmark(int argc, char* argv[]) {
 
       if (valType == "perft")
       {
-          int64_t cnt = perft(pos, limits.maxDepth * ONE_PLY);
+          int64_t cnt = Search::perft(pos, limits.maxDepth * ONE_PLY);
           cerr << "\nPerft " << limits.maxDepth  << " leaf nodes: " << cnt << endl;
           nodes += cnt;
       }
       else
       {
-          Threads.start_thinking(pos, limits, vector<Move>(), false);
+          Threads.start_thinking(pos, limits);
-          nodes += RootPosition.nodes_searched();
+          nodes += Search::RootPosition.nodes_searched();
       }
   }
 

src/bitboard.cpp

@@ -49,9 +49,7 @@ Bitboard SquaresInFrontMask[2][64];
 Bitboard PassedPawnMask[2][64];
 Bitboard AttackSpanMask[2][64];
 
-Bitboard BishopPseudoAttacks[64];
+Bitboard PseudoAttacks[6][64];
-Bitboard RookPseudoAttacks[64];
-Bitboard QueenPseudoAttacks[64];
 
 uint8_t BitCount8Bit[256];
 int SquareDistance[64][64];
@@ -203,7 +201,7 @@ void bitboards_init() {
           Bitboard b = 1ULL << i;
           b ^= b - 1;
           b ^= b >> 32;
-          BSFTable[uint32_t(b * 0x783A9B23) >> 26] = i;
+          BSFTable[(uint32_t)(b * 0x783A9B23) >> 26] = i;
       }
       else
           BSFTable[((1ULL << i) * 0x218A392CD3D5DBFULL) >> 58] = i;
@@ -227,14 +225,14 @@ void bitboards_init() {
 
   for (Square s = SQ_A1; s <= SQ_H8; s++)
   {
-      BishopPseudoAttacks[s] = bishop_attacks_bb(s, 0);
+      PseudoAttacks[BISHOP][s] = bishop_attacks_bb(s, 0);
-      RookPseudoAttacks[s]   = rook_attacks_bb(s, 0);
+      PseudoAttacks[ROOK][s]   = rook_attacks_bb(s, 0);
-      QueenPseudoAttacks[s]  = queen_attacks_bb(s, 0);
+      PseudoAttacks[QUEEN][s]  = queen_attacks_bb(s, 0);
   }
 
   for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
       for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
-          if (bit_is_set(QueenPseudoAttacks[s1], s2))
+          if (bit_is_set(PseudoAttacks[QUEEN][s1], s2))
           {
               Square delta = (s2 - s1) / square_distance(s1, s2);
 

src/bitboard.h

@@ -49,9 +49,7 @@ extern int BShifts[64];
 extern Bitboard BMasks[64];
 extern Bitboard* BAttacks[64];
 
-extern Bitboard BishopPseudoAttacks[64];
+extern Bitboard PseudoAttacks[6][64];
-extern Bitboard RookPseudoAttacks[64];
-extern Bitboard QueenPseudoAttacks[64];
 
 extern uint8_t BitCount8Bit[256];
 

src/endgame.cpp

@@ -205,10 +205,10 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
   }
   else
   {
-      wksq = flip(pos.king_square(BLACK));
+      wksq = ~pos.king_square(BLACK);
-      bksq = flip(pos.king_square(WHITE));
+      bksq = ~pos.king_square(WHITE);
-      wpsq = flip(pos.piece_list(BLACK, PAWN)[0]);
+      wpsq = ~pos.piece_list(BLACK, PAWN)[0];
-      stm = flip(pos.side_to_move());
+      stm  = ~pos.side_to_move();
   }
 
   if (file_of(wpsq) >= FILE_E)
@@ -251,10 +251,10 @@ Value Endgame<KRKP>::operator()(const Position& pos) const {
 
   if (strongerSide == BLACK)
   {
-      wksq = flip(wksq);
+      wksq = ~wksq;
-      wrsq = flip(wrsq);
+      wrsq = ~wrsq;
-      bksq = flip(bksq);
+      bksq = ~bksq;
-      bpsq = flip(bpsq);
+      bpsq = ~bpsq;
   }
 
   Square queeningSq = make_square(file_of(bpsq), RANK_1);
@@ -491,11 +491,11 @@ ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
   // pawn is on the left half of the board.
   if (strongerSide == BLACK)
   {
-      wksq = flip(wksq);
+      wksq = ~wksq;
-      wrsq = flip(wrsq);
+      wrsq = ~wrsq;
-      wpsq = flip(wpsq);
+      wpsq = ~wpsq;
-      bksq = flip(bksq);
+      bksq = ~bksq;
-      brsq = flip(brsq);
+      brsq = ~brsq;
   }
   if (file_of(wpsq) > FILE_D)
   {
@@ -867,10 +867,10 @@ ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
 
   if (strongerSide == BLACK)
   {
-      wksq = flip(wksq);
+      wksq = ~wksq;
-      bksq = flip(bksq);
+      bksq = ~bksq;
-      wpsq = flip(wpsq);
+      wpsq = ~wpsq;
-      stm = flip(stm);
+      stm  = ~stm;
   }
 
   if (file_of(wpsq) >= FILE_E)

src/endgame.h

@@ -82,7 +82,7 @@ struct EndgameBase {
 template<EndgameType E, typename T = typename eg_family<E>::type>
 struct Endgame : public EndgameBase<T> {
 
-  explicit Endgame(Color c) : strongerSide(c), weakerSide(flip(c)) {}
+  explicit Endgame(Color c) : strongerSide(c), weakerSide(~c) {}
   Color color() const { return strongerSide; }
   T operator()(const Position&) const;
 

src/evaluate.cpp

@@ -714,7 +714,7 @@ namespace {
         b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
 
         // Consider only squares where the enemy rook gives check
-        b &= RookPseudoAttacks[ksq];
+        b &= PseudoAttacks[ROOK][ksq];
 
         if (b)
         {
@@ -887,7 +887,7 @@ namespace {
     for (c = WHITE; c <= BLACK; c++)
     {
         // Skip if other side has non-pawn pieces
-        if (pos.non_pawn_material(flip(c)))
+        if (pos.non_pawn_material(~c))
             continue;
 
         b = ei.pi->passed_pawns(c);
@@ -900,7 +900,7 @@ namespace {
 
             // Compute plies to queening and check direct advancement
             movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(c, s) == RANK_2);
-            oppMovesToGo = square_distance(pos.king_square(flip(c)), queeningSquare) - int(c != pos.side_to_move());
+            oppMovesToGo = square_distance(pos.king_square(~c), queeningSquare) - int(c != pos.side_to_move());
             pathDefended = ((ei.attackedBy[c][0] & queeningPath) == queeningPath);
 
             if (movesToGo >= oppMovesToGo && !pathDefended)
@@ -928,7 +928,7 @@ namespace {
         return SCORE_ZERO;
 
     winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK);
-    loserSide = flip(winnerSide);
+    loserSide = ~winnerSide;
 
     // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
     b = candidates = pos.pieces(PAWN, loserSide);

src/lock.h

@@ -45,26 +45,9 @@ typedef pthread_cond_t WaitCondition;
 #undef WIN32_LEAN_AND_MEAN
 #undef NOMINMAX
 
-// Default fast and race free locks and condition variables
+// We use critical sections on Windows to support Windows XP and older versions,
-#if !defined(OLD_LOCKS)
+// unfortunatly cond_wait() is racy between lock_release() and WaitForSingleObject()
-
+// but apart from this they have the same speed performance of SRW locks.
-typedef SRWLOCK Lock;
-typedef CONDITION_VARIABLE WaitCondition;
-
-#  define lock_init(x) InitializeSRWLock(x)
-#  define lock_grab(x) AcquireSRWLockExclusive(x)
-#  define lock_release(x) ReleaseSRWLockExclusive(x)
-#  define lock_destroy(x) (x)
-#  define cond_destroy(x) (x)
-#  define cond_init(x) InitializeConditionVariable(x)
-#  define cond_signal(x) WakeConditionVariable(x)
-#  define cond_wait(x,y) SleepConditionVariableSRW(x,y,INFINITE,0)
-#  define cond_timedwait(x,y,z) SleepConditionVariableSRW(x,y,z,0)
-
-// Fallback solution to build for Windows XP and older versions, note that
-// cond_wait() is racy between lock_release() and WaitForSingleObject().
-#else
-
 typedef CRITICAL_SECTION Lock;
 typedef HANDLE WaitCondition;
 
@@ -80,6 +63,4 @@ typedef HANDLE WaitCondition;
 
 #endif
 
-#endif
-
 #endif // !defined(LOCK_H_INCLUDED)

src/material.cpp

@@ -203,13 +203,13 @@ MaterialInfo* MaterialInfoTable::material_info(const Position& pos) const {
   // No pawns makes it difficult to win, even with a material advantage
   if (pos.piece_count(WHITE, PAWN) == 0 && npm_w - npm_b <= BishopValueMidgame)
   {
-      mi->factor[WHITE] = uint8_t
+      mi->factor[WHITE] = (uint8_t)
       (npm_w == npm_b || npm_w < RookValueMidgame ? 0 : NoPawnsSF[std::min(pos.piece_count(WHITE, BISHOP), 2)]);
   }
 
   if (pos.piece_count(BLACK, PAWN) == 0 && npm_b - npm_w <= BishopValueMidgame)
   {
-      mi->factor[BLACK] = uint8_t
+      mi->factor[BLACK] = (uint8_t)
       (npm_w == npm_b || npm_b < RookValueMidgame ? 0 : NoPawnsSF[std::min(pos.piece_count(BLACK, BISHOP), 2)]);
   }
 
@@ -231,7 +231,7 @@ MaterialInfo* MaterialInfoTable::material_info(const Position& pos) const {
   { pos.piece_count(BLACK, BISHOP) > 1, pos.piece_count(BLACK, PAWN), pos.piece_count(BLACK, KNIGHT),
     pos.piece_count(BLACK, BISHOP)    , pos.piece_count(BLACK, ROOK), pos.piece_count(BLACK, QUEEN) } };
 
-  mi->value = int16_t((imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16);
+  mi->value = (int16_t)((imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16);
   return mi;
 }
 

src/misc.cpp

@@ -55,7 +55,7 @@ using namespace std;
 /// Version number. If Version is left empty, then Tag plus current
 /// date (in the format YYMMDD) is used as a version number.
 
-static const string Version = "2.2.1";
+static const string Version = "2.2.2";
 static const string Tag = "";
 
 

src/move.cpp

@@ -147,13 +147,13 @@ const string move_to_san(Position& pos, Move m) {
       }
   }
 
-  // The move gives check? We don't use pos.move_gives_check() here
+  if (pos.move_gives_check(m, CheckInfo(pos)))
-  // because we need to test for a mate after the move is done.
+  {
       StateInfo st;
       pos.do_move(m, st);
-  if (pos.in_check())
+      san += MoveList<MV_LEGAL>(pos).size() ? "+" : "#";
-      san += pos.is_mate() ? "#" : "+";
       pos.undo_move(m);
+  }
 
   return san;
 }

src/movegen.cpp

@@ -17,50 +17,238 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <cassert>
 #include <algorithm>
+#include <cassert>
 
-#include "bitcount.h"
 #include "movegen.h"
 #include "position.h"
 
-// Simple macro to wrap a very common while loop, no facny, no flexibility,
+/// Simple macro to wrap a very common while loop, no facny, no flexibility,
-// hardcoded list name 'mlist' and from square 'from'.
+/// hardcoded names 'mlist' and 'from'.
-#define SERIALIZE_MOVES(b) while (b) (*mlist++).move = make_move(from, pop_1st_bit(&b))
+#define SERIALIZE(b) while (b) (*mlist++).move = make_move(from, pop_1st_bit(&b))
-
-// Version used for pawns, where the 'from' square is given as a delta from the 'to' square
-#define SERIALIZE_MOVES_D(b, d) while (b) { to = pop_1st_bit(&b); (*mlist++).move = make_move(to + (d), to); }
 
+/// Version used for pawns, where the 'from' square is given as a delta from the 'to' square
+#define SERIALIZE_PAWNS(b, d) while (b) { Square to = pop_1st_bit(&b); \
+                                         (*mlist++).move = make_move(to + (d), to); }
 namespace {
 
-  enum CastlingSide {
+  enum CastlingSide { KING_SIDE, QUEEN_SIDE };
-    KING_SIDE,
-    QUEEN_SIDE
-  };
 
-  template<CastlingSide>
+  template<CastlingSide Side, bool OnlyChecks>
-  MoveStack* generate_castle_moves(const Position&, MoveStack*, Color us);
+  MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist, Color us) {
 
-  template<Color, MoveType>
+    const CastleRight CR[] = { Side ? WHITE_OOO : WHITE_OO,
-  MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard, Square);
+                               Side ? BLACK_OOO : BLACK_OO };
 
-  template<PieceType Pt>
+    if (!pos.can_castle(CR[us]))
-  inline MoveStack* generate_discovered_checks(const Position& pos, MoveStack* mlist, Square from) {
+        return mlist;
 
-    assert(Pt != QUEEN && Pt != PAWN);
+    // After castling, the rook and king final positions are the same in Chess960
+    // as they would be in standard chess.
+    Square kfrom = pos.king_square(us);
+    Square rfrom = pos.castle_rook_square(CR[us]);
+    Square kto = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
+    Square rto = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1);
+    Bitboard enemies = pos.pieces(~us);
 
-    Bitboard b = pos.attacks_from<Pt>(from) & pos.empty_squares();
+    assert(!pos.in_check());
+    assert(pos.piece_on(kfrom) == make_piece(us, KING));
+    assert(pos.piece_on(rfrom) == make_piece(us, ROOK));
 
-    if (Pt == KING)
+    // Unimpeded rule: All the squares between the king's initial and final squares
-        b &= ~QueenPseudoAttacks[pos.king_square(flip(pos.side_to_move()))];
+    // (including the final square), and all the squares between the rook's initial
+    // and final squares (including the final square), must be vacant except for
+    // the king and castling rook.
+    for (Square s = std::min(rfrom, rto), e = std::max(rfrom, rto); s <= e; s++)
+        if (s != kfrom && s != rfrom && !pos.square_is_empty(s))
+            return mlist;
 
-    SERIALIZE_MOVES(b);
+    for (Square s = std::min(kfrom, kto), e = std::max(kfrom, kto); s <= e; s++)
+        if (  (s != kfrom && s != rfrom && !pos.square_is_empty(s))
+            ||(pos.attackers_to(s) & enemies))
+            return mlist;
+
+    // Because we generate only legal castling moves we need to verify that
+    // when moving the castling rook we do not discover some hidden checker.
+    // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
+    if (pos.is_chess960())
+    {
+        Bitboard occ = pos.occupied_squares();
+        clear_bit(&occ, rfrom);
+        if (pos.attackers_to(kto, occ) & enemies)
             return mlist;
     }
 
+    (*mlist++).move = make_castle(kfrom, rfrom);
+
+    if (OnlyChecks && !pos.move_gives_check((mlist - 1)->move, CheckInfo(pos)))
+        mlist--;
+
+    return mlist;
+  }
+
+
+  template<Square Delta>
+  inline Bitboard move_pawns(Bitboard p) {
+
+    return Delta == DELTA_N  ? p << 8 : Delta == DELTA_S  ? p >> 8 :
+           Delta == DELTA_NE ? p << 9 : Delta == DELTA_SE ? p >> 7 :
+           Delta == DELTA_NW ? p << 7 : Delta == DELTA_SW ? p >> 9 : p;
+  }
+
+
+  template<Square Delta>
+  inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard target) {
+
+    const Bitboard TFileABB = (   Delta == DELTA_NE
+                               || Delta == DELTA_SE ? FileABB : FileHBB);
+
+    Bitboard b = move_pawns<Delta>(pawns) & target & ~TFileABB;
+    SERIALIZE_PAWNS(b, -Delta);
+    return mlist;
+  }
+
+
+  template<MoveType Type, Square Delta>
+  inline MoveStack* generate_promotions(MoveStack* mlist, Bitboard pawnsOn7, Bitboard target, Square ksq) {
+
+    const Bitboard TFileABB = (   Delta == DELTA_NE
+                               || Delta == DELTA_SE ? FileABB : FileHBB);
+
+    Bitboard b = move_pawns<Delta>(pawnsOn7) & target;
+
+    if (Delta != DELTA_N && Delta != DELTA_S)
+        b &= ~TFileABB;
+
+    while (b)
+    {
+        Square to = pop_1st_bit(&b);
+
+        if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
+            (*mlist++).move = make_promotion(to - Delta, to, QUEEN);
+
+        if (Type == MV_NON_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
+        {
+            (*mlist++).move = make_promotion(to - Delta, to, ROOK);
+            (*mlist++).move = make_promotion(to - Delta, to, BISHOP);
+            (*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
+        }
+
+        // Knight-promotion is the only one that can give a check (direct or
+        // discovered) not already included in the queen-promotion.
+        if (Type == MV_NON_CAPTURE_CHECK && bit_is_set(StepAttacksBB[W_KNIGHT][to], ksq))
+            (*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
+        else
+            (void)ksq; // Silence a warning under MSVC
+    }
+    return mlist;
+  }
+
+
+  template<Color Us, MoveType Type>
+  MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {
+
+    // Calculate our parametrized parameters at compile time, named according to
+    // the point of view of white side.
+    const Color    Them     = (Us == WHITE ? BLACK    : WHITE);
+    const Bitboard TRank7BB = (Us == WHITE ? Rank7BB  : Rank2BB);
+    const Bitboard TRank3BB = (Us == WHITE ? Rank3BB  : Rank6BB);
+    const Square   UP       = (Us == WHITE ? DELTA_N  : DELTA_S);
+    const Square   RIGHT    = (Us == WHITE ? DELTA_NE : DELTA_SW);
+    const Square   LEFT     = (Us == WHITE ? DELTA_NW : DELTA_SE);
+
+    Bitboard b1, b2, dc1, dc2, emptySquares;
+
+    Bitboard pawnsOn7    = pos.pieces(PAWN, Us) &  TRank7BB;
+    Bitboard pawnsNotOn7 = pos.pieces(PAWN, Us) & ~TRank7BB;
+
+    Bitboard enemies = (Type == MV_EVASION ? pos.pieces(Them) & target:
+                        Type == MV_CAPTURE ? target : pos.pieces(Them));
+
+    // Single and double pawn pushes, no promotions
+    if (Type != MV_CAPTURE)
+    {
+        emptySquares = (Type == MV_NON_CAPTURE ? target : pos.empty_squares());
+
+        b1 = move_pawns<UP>(pawnsNotOn7)   & emptySquares;
+        b2 = move_pawns<UP>(b1 & TRank3BB) & emptySquares;
+
+        if (Type == MV_EVASION) // Consider only blocking squares
+        {
+            b1 &= target;
+            b2 &= target;
+        }
+
+        if (Type == MV_NON_CAPTURE_CHECK)
+        {
+            // Consider only direct checks
+            b1 &= pos.attacks_from<PAWN>(ksq, Them);
+            b2 &= pos.attacks_from<PAWN>(ksq, Them);
+
+            // Add pawn pushes which give discovered check. This is possible only
+            // if the pawn is not on the same file as the enemy king, because we
+            // don't generate captures. Note that a possible discovery check
+            // promotion has been already generated among captures.
+            if (pawnsNotOn7 & target) // Target is dc bitboard
+            {
+                dc1 = move_pawns<UP>(pawnsNotOn7 & target) & emptySquares & ~file_bb(ksq);
+                dc2 = move_pawns<UP>(dc1 & TRank3BB) & emptySquares;
+
+                b1 |= dc1;
+                b2 |= dc2;
+            }
+        }
+
+        SERIALIZE_PAWNS(b1, -UP);
+        SERIALIZE_PAWNS(b2, -UP -UP);
+    }
+
+    // Promotions and underpromotions
+    if (pawnsOn7)
+    {
+        if (Type == MV_CAPTURE)
+            emptySquares = pos.empty_squares();
+
+        if (Type == MV_EVASION)
+            emptySquares &= target;
+
+        mlist = generate_promotions<Type, RIGHT>(mlist, pawnsOn7, enemies, ksq);
+        mlist = generate_promotions<Type, LEFT>(mlist, pawnsOn7, enemies, ksq);
+        mlist = generate_promotions<Type, UP>(mlist, pawnsOn7, emptySquares, ksq);
+    }
+
+    // Standard and en-passant captures
+    if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
+    {
+        mlist = generate_pawn_captures<RIGHT>(mlist, pawnsNotOn7, enemies);
+        mlist = generate_pawn_captures<LEFT >(mlist, pawnsNotOn7, enemies);
+
+        if (pos.ep_square() != SQ_NONE)
+        {
+            assert(rank_of(pos.ep_square()) == (Us == WHITE ? RANK_6 : RANK_3));
+
+            // An en passant capture can be an evasion only if the checking piece
+            // is the double pushed pawn and so is in the target. Otherwise this
+            // is a discovery check and we are forced to do otherwise.
+            if (Type == MV_EVASION && !bit_is_set(target, pos.ep_square() - UP))
+                return mlist;
+
+            b1 = pawnsNotOn7 & pos.attacks_from<PAWN>(pos.ep_square(), Them);
+
+            assert(b1);
+
+            while (b1)
+                (*mlist++).move = make_enpassant(pop_1st_bit(&b1), pos.ep_square());
+        }
+    }
+
+    return mlist;
+  }
+
+
   template<PieceType Pt>
-  inline MoveStack* generate_direct_checks(const Position& pos, MoveStack* mlist, Color us,
+  inline MoveStack* generate_direct_checks(const Position& pos, MoveStack* mlist,
-                                           Bitboard dc, Square ksq) {
+                                           Color us, const CheckInfo& ci) {
     assert(Pt != KING && Pt != PAWN);
 
     Bitboard checkSqs, b;
@@ -70,41 +258,44 @@ namespace {
     if ((from = *pl++) == SQ_NONE)
         return mlist;
 
-    checkSqs = pos.attacks_from<Pt>(ksq) & pos.empty_squares();
+    checkSqs = ci.checkSq[Pt] & pos.empty_squares();
 
     do
     {
-        if (   (Pt == QUEEN  && !(QueenPseudoAttacks[from]  & checkSqs))
+        if (    (Pt == BISHOP || Pt == ROOK || Pt == QUEEN)
-            || (Pt == ROOK   && !(RookPseudoAttacks[from]   & checkSqs))
+            && !(PseudoAttacks[Pt][from] & checkSqs))
-            || (Pt == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
             continue;
 
-        if (dc && bit_is_set(dc, from))
+        if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
             continue;
 
         b = pos.attacks_from<Pt>(from) & checkSqs;
-        SERIALIZE_MOVES(b);
+        SERIALIZE(b);
 
     } while ((from = *pl++) != SQ_NONE);
 
     return mlist;
   }
 
-  template<>
-  FORCE_INLINE MoveStack* generate_direct_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
 
-    return (us == WHITE ? generate_pawn_moves<WHITE, MV_CHECK>(p, m, dc, ksq)
+  template<>
-                        : generate_pawn_moves<BLACK, MV_CHECK>(p, m, dc, ksq));
+  FORCE_INLINE MoveStack* generate_direct_checks<PAWN>(const Position& p, MoveStack* m,
+                                                       Color us, const CheckInfo& ci) {
+
+    return us == WHITE ? generate_pawn_moves<WHITE, MV_NON_CAPTURE_CHECK>(p, m, ci.dcCandidates, ci.ksq)
+                       : generate_pawn_moves<BLACK, MV_NON_CAPTURE_CHECK>(p, m, ci.dcCandidates, ci.ksq);
   }
 
+
   template<PieceType Pt, MoveType Type>
   FORCE_INLINE MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us, Bitboard t) {
 
     assert(Pt == PAWN);
-    return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m, t, SQ_NONE)
+    return us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m, t, SQ_NONE)
-                        : generate_pawn_moves<BLACK, Type>(p, m, t, SQ_NONE));
+                       : generate_pawn_moves<BLACK, Type>(p, m, t, SQ_NONE);
   }
 
+
   template<PieceType Pt>
   FORCE_INLINE MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
 
@@ -117,24 +308,23 @@ namespace {
         do {
             from = *pl;
             b = pos.attacks_from<Pt>(from) & target;
-            SERIALIZE_MOVES(b);
+            SERIALIZE(b);
         } while (*++pl != SQ_NONE);
     }
     return mlist;
   }
 
+
   template<>
   FORCE_INLINE MoveStack* generate_piece_moves<KING>(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
 
-    Bitboard b;
     Square from = pos.king_square(us);
-
+    Bitboard b = pos.attacks_from<KING>(from) & target;
-    b = pos.attacks_from<KING>(from) & target;
+    SERIALIZE(b);
-    SERIALIZE_MOVES(b);
     return mlist;
   }
 
-}
+} // namespace
 
 
 /// generate<MV_CAPTURE> generates all pseudo-legal captures and queen
@@ -156,13 +346,13 @@ MoveStack* generate(const Position& pos, MoveStack* mlist) {
   Bitboard target;
 
   if (Type == MV_CAPTURE)
-      target = pos.pieces(flip(us));
+      target = pos.pieces(~us);
 
   else if (Type == MV_NON_CAPTURE)
       target = pos.empty_squares();
 
   else if (Type == MV_NON_EVASION)
-      target = pos.pieces(flip(us)) | pos.empty_squares();
+      target = pos.pieces(~us) | pos.empty_squares();
 
   mlist = generate_piece_moves<PAWN, Type>(pos, mlist, us, target);
   mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
@@ -173,11 +363,8 @@ MoveStack* generate(const Position& pos, MoveStack* mlist) {
 
   if (Type != MV_CAPTURE && pos.can_castle(us))
   {
-      if (pos.can_castle(us == WHITE ? WHITE_OO : BLACK_OO))
+      mlist = generate_castle_moves<KING_SIDE, false>(pos, mlist, us);
-          mlist = generate_castle_moves<KING_SIDE>(pos, mlist, us);
+      mlist = generate_castle_moves<QUEEN_SIDE, false>(pos, mlist, us);
-
-      if (pos.can_castle(us == WHITE ? WHITE_OOO : BLACK_OOO))
-          mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist, us);
   }
 
   return mlist;
@@ -196,36 +383,39 @@ MoveStack* generate<MV_NON_CAPTURE_CHECK>(const Position& pos, MoveStack* mlist)
 
   assert(!pos.in_check());
 
-  Bitboard b, dc;
-  Square from;
   Color us = pos.side_to_move();
-  Square ksq = pos.king_square(flip(us));
+  CheckInfo ci(pos);
+  Bitboard dc = ci.dcCandidates;
 
-  assert(pos.piece_on(ksq) == make_piece(flip(us), KING));
+  while (dc)
-
-  // Discovered non-capture checks
-  b = dc = pos.discovered_check_candidates();
-
-  while (b)
   {
-     from = pop_1st_bit(&b);
+     Square from = pop_1st_bit(&dc);
-     switch (type_of(pos.piece_on(from)))
+     PieceType pt = type_of(pos.piece_on(from));
-     {
+
-      case PAWN:   /* Will be generated togheter with pawns direct checks */     break;
+     if (pt == PAWN)
-      case KNIGHT: mlist = generate_discovered_checks<KNIGHT>(pos, mlist, from); break;
+         continue; // Will be generated togheter with direct checks
-      case BISHOP: mlist = generate_discovered_checks<BISHOP>(pos, mlist, from); break;
+
-      case ROOK:   mlist = generate_discovered_checks<ROOK>(pos, mlist, from);   break;
+     Bitboard b = pos.attacks_from(Piece(pt), from) & pos.empty_squares();
-      case KING:   mlist = generate_discovered_checks<KING>(pos, mlist, from);   break;
+
-      default: assert(false); break;
+     if (pt == KING)
-     }
+         b &= ~PseudoAttacks[QUEEN][ci.ksq];
+
+     SERIALIZE(b);
   }
 
-  // Direct non-capture checks
+  mlist = generate_direct_checks<PAWN>(pos, mlist, us, ci);
-  mlist = generate_direct_checks<PAWN>(pos, mlist, us, dc, ksq);
+  mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, ci);
-  mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, dc, ksq);
+  mlist = generate_direct_checks<BISHOP>(pos, mlist, us, ci);
-  mlist = generate_direct_checks<BISHOP>(pos, mlist, us, dc, ksq);
+  mlist = generate_direct_checks<ROOK>(pos, mlist, us, ci);
-  mlist = generate_direct_checks<ROOK>(pos, mlist, us, dc, ksq);
+  mlist = generate_direct_checks<QUEEN>(pos, mlist, us, ci);
-  return  generate_direct_checks<QUEEN>(pos, mlist, us, dc, ksq);
+
+  if (pos.can_castle(us))
+  {
+      mlist = generate_castle_moves<KING_SIDE, true>(pos, mlist, us);
+      mlist = generate_castle_moves<QUEEN_SIDE, true>(pos, mlist, us);
+  }
+
+  return mlist;
 }
 
 
@@ -241,38 +431,37 @@ MoveStack* generate<MV_EVASION>(const Position& pos, MoveStack* mlist) {
   int checkersCnt = 0;
   Color us = pos.side_to_move();
   Square ksq = pos.king_square(us);
-  Bitboard checkers = pos.checkers();
   Bitboard sliderAttacks = 0;
+  Bitboard checkers = pos.checkers();
 
-  assert(pos.piece_on(ksq) == make_piece(us, KING));
   assert(checkers);
 
-  // Find squares attacked by slider checkers, we will remove
+  // Find squares attacked by slider checkers, we will remove them from the king
-  // them from the king evasions set so to early skip known
+  // evasions so to skip known illegal moves avoiding useless legality check later.
-  // illegal moves and avoid an useless legality check later.
   b = checkers;
   do
   {
       checkersCnt++;
       checksq = pop_1st_bit(&b);
 
-      assert(color_of(pos.piece_on(checksq)) == flip(us));
+      assert(color_of(pos.piece_on(checksq)) == ~us);
 
       switch (type_of(pos.piece_on(checksq)))
       {
-      case BISHOP: sliderAttacks |= BishopPseudoAttacks[checksq]; break;
+      case BISHOP: sliderAttacks |= PseudoAttacks[BISHOP][checksq]; break;
-      case ROOK:   sliderAttacks |= RookPseudoAttacks[checksq];   break;
+      case ROOK:   sliderAttacks |= PseudoAttacks[ROOK][checksq];   break;
       case QUEEN:
-          // If queen and king are far we can safely remove all the squares attacked
+          // If queen and king are far or not on a diagonal line we can safely
-          // in the other direction becuase are not reachable by the king anyway.
+          // remove all the squares attacked in the other direction becuase are
-          if (squares_between(ksq, checksq) || (RookPseudoAttacks[checksq] & (1ULL << ksq)))
+          // not reachable by the king anyway.
-              sliderAttacks |= QueenPseudoAttacks[checksq];
+          if (squares_between(ksq, checksq) || !bit_is_set(PseudoAttacks[BISHOP][checksq], ksq))
+              sliderAttacks |= PseudoAttacks[QUEEN][checksq];
 
-          // Otherwise, if king and queen are adjacent and on a diagonal line, we need to
+          // Otherwise we need to use real rook attacks to check if king is safe
-          // use real rook attacks to check if king is safe to move in the other direction.
+          // to move in the other direction. For example: king in B2, queen in A1
-          // For example: king in B2, queen in A1 a knight in B1, and we can safely move to C1.
+          // a knight in B1, and we can safely move to C1.
           else
-              sliderAttacks |= BishopPseudoAttacks[checksq] | pos.attacks_from<ROOK>(checksq);
+              sliderAttacks |= PseudoAttacks[BISHOP][checksq] | pos.attacks_from<ROOK>(checksq);
 
       default:
           break;
@@ -282,14 +471,13 @@ MoveStack* generate<MV_EVASION>(const Position& pos, MoveStack* mlist) {
   // Generate evasions for king, capture and non capture moves
   b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
   from = ksq;
-  SERIALIZE_MOVES(b);
+  SERIALIZE(b);
 
-  // Generate evasions for other pieces only if not double check
+  // Generate evasions for other pieces only if not under a double check
   if (checkersCnt > 1)
       return mlist;
 
-  // Find squares where a blocking evasion or a capture of the
+  // Blocking evasions or captures of the checking piece
-  // checker piece is possible.
   target = squares_between(checksq, ksq) | checkers;
 
   mlist = generate_piece_moves<PAWN, MV_EVASION>(pos, mlist, us, target);
@@ -300,7 +488,7 @@ MoveStack* generate<MV_EVASION>(const Position& pos, MoveStack* mlist) {
 }
 
 
-/// generate<MV_LEGAL> computes a complete list of legal moves in the current position
+/// generate<MV_LEGAL> generates all the legal moves in the given position
 
 template<>
 MoveStack* generate<MV_LEGAL>(const Position& pos, MoveStack* mlist) {
@@ -310,8 +498,6 @@ MoveStack* generate<MV_LEGAL>(const Position& pos, MoveStack* mlist) {
 
   last = pos.in_check() ? generate<MV_EVASION>(pos, mlist)
                         : generate<MV_NON_EVASION>(pos, mlist);
-
-  // Remove illegal moves from the list
   while (cur != last)
       if (!pos.pl_move_is_legal(cur->move, pinned))
           cur->move = (--last)->move;
@@ -320,218 +506,3 @@ MoveStack* generate<MV_LEGAL>(const Position& pos, MoveStack* mlist) {
 
   return last;
 }
-
-
-namespace {
-
-  template<Square Delta>
-  inline Bitboard move_pawns(Bitboard p) {
-
-    return Delta == DELTA_N  ? p << 8 : Delta == DELTA_S  ? p >> 8 :
-           Delta == DELTA_NE ? p << 9 : Delta == DELTA_SE ? p >> 7 :
-           Delta == DELTA_NW ? p << 7 : Delta == DELTA_SW ? p >> 9 : p;
-  }
-
-  template<Square Delta>
-  inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard target) {
-
-    const Bitboard TFileABB = (Delta == DELTA_NE || Delta == DELTA_SE ? FileABB : FileHBB);
-
-    Bitboard b;
-    Square to;
-
-    // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
-    b = move_pawns<Delta>(pawns) & target & ~TFileABB;
-    SERIALIZE_MOVES_D(b, -Delta);
-    return mlist;
-  }
-
-  template<MoveType Type, Square Delta>
-  inline MoveStack* generate_promotions(const Position& pos, MoveStack* mlist, Bitboard pawnsOn7, Bitboard target) {
-
-    const Bitboard TFileABB = (Delta == DELTA_NE || Delta == DELTA_SE ? FileABB : FileHBB);
-
-    Bitboard b;
-    Square to;
-
-    // Promotions and under-promotions, both captures and non-captures
-    b = move_pawns<Delta>(pawnsOn7) & target;
-
-    if (Delta != DELTA_N && Delta != DELTA_S)
-        b &= ~TFileABB;
-
-    while (b)
-    {
-        to = pop_1st_bit(&b);
-
-        if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
-            (*mlist++).move = make_promotion(to - Delta, to, QUEEN);
-
-        if (Type == MV_NON_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
-        {
-            (*mlist++).move = make_promotion(to - Delta, to, ROOK);
-            (*mlist++).move = make_promotion(to - Delta, to, BISHOP);
-            (*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
-        }
-
-        // This is the only possible under promotion that can give a check
-        // not already included in the queen-promotion.
-        if (   Type == MV_CHECK
-            && bit_is_set(pos.attacks_from<KNIGHT>(to), pos.king_square(Delta > 0 ? BLACK : WHITE)))
-            (*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
-        else (void)pos; // Silence a warning under MSVC
-    }
-    return mlist;
-  }
-
-  template<Color Us, MoveType Type>
-  MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {
-
-    // Calculate our parametrized parameters at compile time, named
-    // according to the point of view of white side.
-    const Color    Them      = (Us == WHITE ? BLACK    : WHITE);
-    const Bitboard TRank7BB  = (Us == WHITE ? Rank7BB  : Rank2BB);
-    const Bitboard TRank3BB  = (Us == WHITE ? Rank3BB  : Rank6BB);
-    const Square   UP        = (Us == WHITE ? DELTA_N  : DELTA_S);
-    const Square   RIGHT_UP  = (Us == WHITE ? DELTA_NE : DELTA_SW);
-    const Square   LEFT_UP   = (Us == WHITE ? DELTA_NW : DELTA_SE);
-
-    Square to;
-    Bitboard b1, b2, dc1, dc2, pawnPushes, emptySquares;
-    Bitboard pawns = pos.pieces(PAWN, Us);
-    Bitboard pawnsOn7 = pawns & TRank7BB;
-    Bitboard enemyPieces = (Type == MV_CAPTURE ? target : pos.pieces(Them));
-
-    // Pre-calculate pawn pushes before changing emptySquares definition
-    if (Type != MV_CAPTURE)
-    {
-        emptySquares = (Type == MV_NON_CAPTURE ? target : pos.empty_squares());
-        pawnPushes = move_pawns<UP>(pawns & ~TRank7BB) & emptySquares;
-    }
-
-    if (Type == MV_EVASION)
-    {
-        emptySquares &= target; // Only blocking squares
-        enemyPieces  &= target; // Capture only the checker piece
-    }
-
-    // Promotions and underpromotions
-    if (pawnsOn7)
-    {
-        if (Type == MV_CAPTURE)
-            emptySquares = pos.empty_squares();
-
-        pawns &= ~TRank7BB;
-        mlist = generate_promotions<Type, RIGHT_UP>(pos, mlist, pawnsOn7, enemyPieces);
-        mlist = generate_promotions<Type, LEFT_UP>(pos, mlist, pawnsOn7, enemyPieces);
-        mlist = generate_promotions<Type, UP>(pos, mlist, pawnsOn7, emptySquares);
-    }
-
-    // Standard captures
-    if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
-    {
-        mlist = generate_pawn_captures<RIGHT_UP>(mlist, pawns, enemyPieces);
-        mlist = generate_pawn_captures<LEFT_UP>(mlist, pawns, enemyPieces);
-    }
-
-    // Single and double pawn pushes
-    if (Type != MV_CAPTURE)
-    {
-        b1 = (Type != MV_EVASION ? pawnPushes : pawnPushes & emptySquares);
-        b2 = move_pawns<UP>(pawnPushes & TRank3BB) & emptySquares;
-
-        if (Type == MV_CHECK)
-        {
-            // Consider only pawn moves which give direct checks
-            b1 &= pos.attacks_from<PAWN>(ksq, Them);
-            b2 &= pos.attacks_from<PAWN>(ksq, Them);
-
-            // Add pawn moves which gives discovered check. This is possible only
-            // if the pawn is not on the same file as the enemy king, because we
-            // don't generate captures.
-            if (pawns & target) // For CHECK type target is dc bitboard
-            {
-                dc1 = move_pawns<UP>(pawns & target & ~file_bb(ksq)) & emptySquares;
-                dc2 = move_pawns<UP>(dc1 & TRank3BB) & emptySquares;
-
-                b1 |= dc1;
-                b2 |= dc2;
-            }
-        }
-        SERIALIZE_MOVES_D(b1, -UP);
-        SERIALIZE_MOVES_D(b2, -UP -UP);
-    }
-
-    // En passant captures
-    if (  (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
-        && pos.ep_square() != SQ_NONE)
-    {
-        assert(Us != WHITE || rank_of(pos.ep_square()) == RANK_6);
-        assert(Us != BLACK || rank_of(pos.ep_square()) == RANK_3);
-
-        // An en passant capture can be an evasion only if the checking piece
-        // is the double pushed pawn and so is in the target. Otherwise this
-        // is a discovery check and we are forced to do otherwise.
-        if (Type == MV_EVASION && !bit_is_set(target, pos.ep_square() - UP))
-            return mlist;
-
-        b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);
-
-        assert(b1);
-
-        while (b1)
-        {
-            to = pop_1st_bit(&b1);
-            (*mlist++).move = make_enpassant(to, pos.ep_square());
-        }
-    }
-    return mlist;
-  }
-
-  template<CastlingSide Side>
-  MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist, Color us) {
-
-    CastleRight f = CastleRight((Side == KING_SIDE ? WHITE_OO : WHITE_OOO) << us);
-    Color them = flip(us);
-
-    // After castling, the rook and king's final positions are exactly the same
-    // in Chess960 as they would be in standard chess.
-    Square kfrom = pos.king_square(us);
-    Square rfrom = pos.castle_rook_square(f);
-    Square kto = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
-    Square rto = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1);
-
-    assert(!pos.in_check());
-    assert(pos.piece_on(kfrom) == make_piece(us, KING));
-    assert(pos.piece_on(rfrom) == make_piece(us, ROOK));
-
-    // Unimpeded rule: All the squares between the king's initial and final squares
-    // (including the final square), and all the squares between the rook's initial
-    // and final squares (including the final square), must be vacant except for
-    // the king and castling rook.
-    for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); s++)
-        if (  (s != kfrom && s != rfrom && !pos.square_is_empty(s))
-            ||(pos.attackers_to(s) & pos.pieces(them)))
-            return mlist;
-
-    for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); s++)
-        if (s != kfrom && s != rfrom && !pos.square_is_empty(s))
-            return mlist;
-
-    // Because we generate only legal castling moves we need to verify that
-    // when moving the castling rook we do not discover some hidden checker.
-    // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
-    if (pos.is_chess960())
-    {
-        Bitboard occ = pos.occupied_squares();
-        clear_bit(&occ, rfrom);
-        if (pos.attackers_to(kto, occ) & pos.pieces(them))
-            return mlist;
-    }
-
-    (*mlist++).move = make_castle(kfrom, rfrom);
-
-    return mlist;
-  }
-
-} // namespace

src/movegen.h

@@ -25,7 +25,6 @@
 enum MoveType {
   MV_CAPTURE,
   MV_NON_CAPTURE,
-  MV_CHECK,
   MV_NON_CAPTURE_CHECK,
   MV_EVASION,
   MV_NON_EVASION,

src/movepick.cpp

@@ -255,7 +255,7 @@ void MovePicker::score_captures() {
   {
       m = cur->move;
       cur->score =  PieceValueMidgame[pos.piece_on(to_sq(m))]
-                  - type_of(pos.piece_on(from_sq(m)));
+                  - type_of(pos.piece_moved(m));
 
       if (is_promotion(m))
           cur->score += PieceValueMidgame[Piece(promotion_piece_type(m))];
@@ -294,9 +294,9 @@ void MovePicker::score_evasions() {
           cur->score = seeScore - History::MaxValue; // Be sure we are at the bottom
       else if (pos.is_capture(m))
           cur->score =  PieceValueMidgame[pos.piece_on(to_sq(m))]
-                      - type_of(pos.piece_on(from_sq(m))) + History::MaxValue;
+                      - type_of(pos.piece_moved(m)) + History::MaxValue;
       else
-          cur->score = H.value(pos.piece_on(from_sq(m)), to_sq(m));
+          cur->score = H.value(pos.piece_moved(m), to_sq(m));
   }
 }
 

src/position.cpp

@@ -78,8 +78,8 @@ namespace {
 
 CheckInfo::CheckInfo(const Position& pos) {
 
-  Color them = flip(pos.side_to_move());
+  Color them = ~pos.side_to_move();
-  Square ksq = pos.king_square(them);
+  ksq = pos.king_square(them);
 
   pinned = pos.pinned_pieces();
   dcCandidates = pos.discovered_check_candidates();
@@ -165,11 +165,11 @@ void Position::from_fen(const string& fenStr, bool isChess960) {
   // 1. Piece placement
   while ((fen >> token) && !isspace(token))
   {
-      if (token == '/')
+      if (isdigit(token))
-          sq -= Square(16); // Jump back of 2 rows
+          sq += Square(token - '0'); // Advance the given number of files
 
-      else if (isdigit(token))
+      else if (token == '/')
-          sq += Square(token - '0'); // Skip the given number of files
+          sq = make_square(FILE_A, rank_of(sq) - Rank(2));
 
       else if ((p = PieceToChar.find(token)) != string::npos)
       {
@@ -192,15 +192,14 @@ void Position::from_fen(const string& fenStr, bool isChess960) {
   {
       Square rsq;
       Color c = islower(token) ? BLACK : WHITE;
-      Piece rook = make_piece(c, ROOK);
 
       token = char(toupper(token));
 
       if (token == 'K')
-          for (rsq = relative_square(c, SQ_H1); piece_on(rsq) != rook; rsq--) {}
+          for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; rsq--) {}
 
       else if (token == 'Q')
-          for (rsq = relative_square(c, SQ_A1); piece_on(rsq) != rook; rsq++) {}
+          for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; rsq++) {}
 
       else if (token >= 'A' && token <= 'H')
           rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1));
@@ -208,7 +207,7 @@ void Position::from_fen(const string& fenStr, bool isChess960) {
       else
           continue;
 
-      set_castle_right(king_square(c), rsq);
+      set_castle_right(c, rsq);
   }
 
   // 4. En passant square. Ignore if no pawn capture is possible
@@ -234,7 +233,7 @@ void Position::from_fen(const string& fenStr, bool isChess960) {
   st->value = compute_value();
   st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
   st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
-  st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
+  st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
   chess960 = isChess960;
 
   assert(pos_is_ok());
@@ -242,14 +241,14 @@ void Position::from_fen(const string& fenStr, bool isChess960) {
 
 
 /// Position::set_castle_right() is an helper function used to set castling
-/// rights given the corresponding king and rook starting squares.
+/// rights given the corresponding color and the rook starting square.
 
-void Position::set_castle_right(Square ksq, Square rsq) {
+void Position::set_castle_right(Color c, Square rsq) {
 
-  int f = (rsq < ksq ? WHITE_OOO : WHITE_OO) << color_of(piece_on(ksq));
+  int f = (rsq < king_square(c) ? WHITE_OOO : WHITE_OO) << c;
 
   st->castleRights |= f;
-  castleRightsMask[ksq] ^= f;
+  castleRightsMask[king_square(c)] ^= f;
   castleRightsMask[rsq] ^= f;
   castleRookSquare[f] = rsq;
 }
@@ -357,12 +356,12 @@ Bitboard Position::hidden_checkers() const {
 
   // Pinned pieces protect our king, dicovery checks attack the enemy king
   Bitboard b, result = 0;
-  Bitboard pinners = pieces(FindPinned ? flip(sideToMove) : sideToMove);
+  Bitboard pinners = pieces(FindPinned ? ~sideToMove : sideToMove);
-  Square ksq = king_square(FindPinned ? sideToMove : flip(sideToMove));
+  Square ksq = king_square(FindPinned ? sideToMove : ~sideToMove);
 
   // Pinners are sliders, that give check when candidate pinned is removed
-  pinners &=  (pieces(ROOK, QUEEN) & RookPseudoAttacks[ksq])
+  pinners &=  (pieces(ROOK, QUEEN) & PseudoAttacks[ROOK][ksq])
-            | (pieces(BISHOP, QUEEN) & BishopPseudoAttacks[ksq]);
+            | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq]);
 
   while (pinners)
   {
@@ -450,7 +449,7 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
   assert(is_ok(m));
   assert(pinned == pinned_pieces());
 
-  Color us = side_to_move();
+  Color us = sideToMove;
   Square from = from_sq(m);
 
   assert(color_of(piece_on(from)) == us);
@@ -461,7 +460,7 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
   // the move is made.
   if (is_enpassant(m))
   {
-      Color them = flip(us);
+      Color them = ~us;
       Square to = to_sq(m);
       Square capsq = to + pawn_push(them);
       Square ksq = king_square(us);
@@ -484,7 +483,7 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
   // square is attacked by the opponent. Castling moves are checked
   // for legality during move generation.
   if (type_of(piece_on(from)) == KING)
-      return is_castle(m) || !(attackers_to(to_sq(m)) & pieces(flip(us)));
+      return is_castle(m) || !(attackers_to(to_sq(m)) & pieces(~us));
 
   // A non-king move is legal if and only if it is not pinned or it
   // is moving along the ray towards or away from the king.
@@ -515,7 +514,7 @@ bool Position::move_is_legal(const Move m) const {
 bool Position::is_pseudo_legal(const Move m) const {
 
   Color us = sideToMove;
-  Color them = flip(sideToMove);
+  Color them = ~sideToMove;
   Square from = from_sq(m);
   Square to = to_sq(m);
   Piece pc = piece_on(from);
@@ -613,7 +612,7 @@ bool Position::is_pseudo_legal(const Move m) const {
       {
           Bitboard b = occupied_squares();
           clear_bit(&b, from);
-          if (attackers_to(to_sq(m), b) & pieces(flip(us)))
+          if (attackers_to(to_sq(m), b) & pieces(~us))
               return false;
       }
       else
@@ -641,7 +640,7 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
 
   assert(is_ok(m));
   assert(ci.dcCandidates == discovered_check_candidates());
-  assert(color_of(piece_on(from_sq(m))) == side_to_move());
+  assert(color_of(piece_moved(m)) == sideToMove);
 
   Square from = from_sq(m);
   Square to = to_sq(m);
@@ -656,7 +655,7 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
   {
       // For pawn and king moves we need to verify also direction
       if (  (pt != PAWN && pt != KING)
-          || !squares_aligned(from, to, king_square(flip(side_to_move()))))
+          || !squares_aligned(from, to, king_square(~sideToMove)))
           return true;
   }
 
@@ -664,9 +663,9 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
   if (!is_special(m))
       return false;
 
-  Color us = side_to_move();
+  Color us = sideToMove;
   Bitboard b = occupied_squares();
-  Square ksq = king_square(flip(us));
+  Square ksq = king_square(~us);
 
   // Promotion with check ?
   if (is_promotion(m))
@@ -764,8 +763,8 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
       return;
   }
 
-  Color us = side_to_move();
+  Color us = sideToMove;
-  Color them = flip(us);
+  Color them = ~us;
   Square from = from_sq(m);
   Square to = to_sq(m);
   Piece piece = piece_on(from);
@@ -958,7 +957,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
   }
 
   // Finish
-  sideToMove = flip(sideToMove);
+  sideToMove = ~sideToMove;
   st->value += (sideToMove == WHITE ?  TempoValue : -TempoValue);
 
   assert(pos_is_ok());
@@ -972,7 +971,7 @@ void Position::undo_move(Move m) {
 
   assert(is_ok(m));
 
-  sideToMove = flip(sideToMove);
+  sideToMove = ~sideToMove;
 
   if (is_castle(m))
   {
@@ -980,8 +979,8 @@ void Position::undo_move(Move m) {
       return;
   }
 
-  Color us = side_to_move();
+  Color us = sideToMove;
-  Color them = flip(us);
+  Color them = ~us;
   Square from = from_sq(m);
   Square to = to_sq(m);
   Piece piece = piece_on(to);
@@ -1076,7 +1075,7 @@ void Position::do_castle_move(Move m) {
 
   Square kto, kfrom, rfrom, rto, kAfter, rAfter;
 
-  Color us = side_to_move();
+  Color us = sideToMove;
   Square kBefore = from_sq(m);
   Square rBefore = to_sq(m);
 
@@ -1160,10 +1159,10 @@ void Position::do_castle_move(Move m) {
       st->rule50 = 0;
 
       // Update checkers BB
-      st->checkersBB = attackers_to(king_square(flip(us))) & pieces(us);
+      st->checkersBB = attackers_to(king_square(~us)) & pieces(us);
 
       // Finish
-      sideToMove = flip(sideToMove);
+      sideToMove = ~sideToMove;
       st->value += (sideToMove == WHITE ?  TempoValue : -TempoValue);
   }
   else
@@ -1194,7 +1193,7 @@ void Position::do_null_move(StateInfo& backupSt) {
   dst->rule50   = src->rule50;
   dst->pliesFromNull = src->pliesFromNull;
 
-  sideToMove = flip(sideToMove);
+  sideToMove = ~sideToMove;
 
   if (Do)
   {
@@ -1264,9 +1263,9 @@ int Position::see(Move m) const {
   // Handle en passant moves
   if (is_enpassant(m))
   {
-      Square capQq = to - pawn_push(side_to_move());
+      Square capQq = to - pawn_push(sideToMove);
 
-      assert(capturedType == NO_PIECE_TYPE);
+      assert(!capturedType);
       assert(type_of(piece_on(capQq)) == PAWN);
 
       // Remove the captured pawn
@@ -1280,7 +1279,7 @@ int Position::see(Move m) const {
   attackers = attackers_to(to, occ);
 
   // If the opponent has no attackers we are finished
-  stm = flip(color_of(piece_on(from)));
+  stm = ~color_of(piece_on(from));
   stmAttackers = attackers & pieces(stm);
   if (!stmAttackers)
       return PieceValueMidgame[capturedType];
@@ -1318,7 +1317,7 @@ int Position::see(Move m) const {
       // Remember the value of the capturing piece, and change the side to
       // move before beginning the next iteration.
       capturedType = pt;
-      stm = flip(stm);
+      stm = ~stm;
       stmAttackers = attackers & pieces(stm);
 
       // Stop before processing a king capture
@@ -1402,7 +1401,7 @@ Key Position::compute_key() const {
   if (ep_square() != SQ_NONE)
       result ^= zobEp[ep_square()];
 
-  if (side_to_move() == BLACK)
+  if (sideToMove == BLACK)
       result ^= zobSideToMove;
 
   return result;
@@ -1466,7 +1465,7 @@ Score Position::compute_value() const {
               result += pst(make_piece(c, pt), pop_1st_bit(&b));
       }
 
-  result += (side_to_move() == WHITE ? TempoValue / 2 : -TempoValue / 2);
+  result += (sideToMove == WHITE ? TempoValue / 2 : -TempoValue / 2);
   return result;
 }
 
@@ -1499,7 +1498,7 @@ bool Position::is_draw() const {
       return true;
 
   // Draw by the 50 moves rule?
-  if (st->rule50 > 99 && !is_mate())
+  if (st->rule50 > 99 && (!in_check() || MoveList<MV_LEGAL>(*this).size()))
       return true;
 
   // Draw by repetition?
@@ -1531,15 +1530,6 @@ template bool Position::is_draw<false>() const;
 template bool Position::is_draw<true>() const;
 
 
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated.
-
-bool Position::is_mate() const {
-
-  return in_check() && !MoveList<MV_LEGAL>(*this).size();
-}
-
-
 /// Position::init() is a static member function which initializes at startup
 /// the various arrays used to compute hash keys and the piece square tables.
 /// The latter is a two-step operation: First, the white halves of the tables
@@ -1571,7 +1561,7 @@ void Position::init() {
       for (Square s = SQ_A1; s <= SQ_H8; s++)
       {
           pieceSquareTable[p][s] = ps + PSQT[p][s];
-          pieceSquareTable[p+8][flip(s)] = -pieceSquareTable[p][s];
+          pieceSquareTable[p+8][~s] = -pieceSquareTable[p][s];
       }
   }
 }
@@ -1591,27 +1581,27 @@ void Position::flip_me() {
   // Board
   for (Square s = SQ_A1; s <= SQ_H8; s++)
       if (!pos.square_is_empty(s))
-          put_piece(Piece(pos.piece_on(s) ^ 8), flip(s));
+          put_piece(Piece(pos.piece_on(s) ^ 8), ~s);
 
   // Side to move
-  sideToMove = flip(pos.side_to_move());
+  sideToMove = ~pos.side_to_move();
 
   // Castling rights
   if (pos.can_castle(WHITE_OO))
-      set_castle_right(king_square(BLACK), flip(pos.castle_rook_square(WHITE_OO)));
+      set_castle_right(BLACK, ~pos.castle_rook_square(WHITE_OO));
   if (pos.can_castle(WHITE_OOO))
-      set_castle_right(king_square(BLACK), flip(pos.castle_rook_square(WHITE_OOO)));
+      set_castle_right(BLACK, ~pos.castle_rook_square(WHITE_OOO));
   if (pos.can_castle(BLACK_OO))
-      set_castle_right(king_square(WHITE), flip(pos.castle_rook_square(BLACK_OO)));
+      set_castle_right(WHITE, ~pos.castle_rook_square(BLACK_OO));
   if (pos.can_castle(BLACK_OOO))
-      set_castle_right(king_square(WHITE), flip(pos.castle_rook_square(BLACK_OOO)));
+      set_castle_right(WHITE, ~pos.castle_rook_square(BLACK_OOO));
 
   // En passant square
   if (pos.st->epSquare != SQ_NONE)
-      st->epSquare = flip(pos.st->epSquare);
+      st->epSquare = ~pos.st->epSquare;
 
   // Checkers
-  st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
+  st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
 
   // Hash keys
   st->key = compute_key();
@@ -1653,7 +1643,7 @@ bool Position::pos_is_ok(int* failedStep) const {
   if (failedStep) *failedStep = 1;
 
   // Side to move OK?
-  if (side_to_move() != WHITE && side_to_move() != BLACK)
+  if (sideToMove != WHITE && sideToMove != BLACK)
       return false;
 
   // Are the king squares in the position correct?
@@ -1682,8 +1672,8 @@ bool Position::pos_is_ok(int* failedStep) const {
   if (failedStep) (*failedStep)++;
   if (debugKingCapture)
   {
-      Color us = side_to_move();
+      Color us = sideToMove;
-      Color them = flip(us);
+      Color them = ~us;
       Square ksq = king_square(them);
       if (attackers_to(ksq) & pieces(us))
           return false;
@@ -1720,7 +1710,7 @@ bool Position::pos_is_ok(int* failedStep) const {
   {
       // The en passant square must be on rank 6, from the point of view of the
       // side to move.
-      if (relative_rank(side_to_move(), ep_square()) != RANK_6)
+      if (relative_rank(sideToMove, ep_square()) != RANK_6)
           return false;
   }
 

src/position.h

@@ -37,6 +37,7 @@ struct CheckInfo {
   Bitboard dcCandidates;
   Bitboard pinned;
   Bitboard checkSq[8];
+  Square ksq;
 };
 
 
@@ -100,6 +101,7 @@ public:
 
   // The piece on a given square
   Piece piece_on(Square s) const;
+  Piece piece_moved(Move m) const;
   bool square_is_empty(Square s) const;
 
   // Side to move
@@ -183,14 +185,9 @@ public:
   Value non_pawn_material(Color c) const;
   Score pst_delta(Piece piece, Square from, Square to) const;
 
-  // Game termination checks
-  bool is_mate() const;
-  template<bool SkipRepetition> bool is_draw() const;
-
-  // Plies from start position to the beginning of search
-  int startpos_ply_counter() const;
-
   // Other properties of the position
+  template<bool SkipRepetition> bool is_draw() const;
+  int startpos_ply_counter() const;
   bool opposite_colored_bishops() const;
   bool has_pawn_on_7th(Color c) const;
   bool is_chess960() const;
@@ -213,7 +210,7 @@ private:
   // Initialization helper functions (used while setting up a position)
   void clear();
   void put_piece(Piece p, Square s);
-  void set_castle_right(Square ksq, Square rsq);
+  void set_castle_right(Color c, Square rsq);
   bool move_is_legal(const Move m) const;
 
   // Helper template functions
@@ -277,6 +274,10 @@ inline Piece Position::piece_on(Square s) const {
   return board[s];
 }
 
+inline Piece Position::piece_moved(Move m) const {
+  return board[from_sq(m)];
+}
+
 inline bool Position::square_is_empty(Square s) const {
   return board[s] == NO_PIECE;
 }
@@ -391,7 +392,7 @@ inline Bitboard Position::pinned_pieces() const {
 }
 
 inline bool Position::pawn_is_passed(Color c, Square s) const {
-  return !(pieces(PAWN, flip(c)) & passed_pawn_mask(c, s));
+  return !(pieces(PAWN, ~c) & passed_pawn_mask(c, s));
 }
 
 inline Key Position::key() const {

src/search.cpp

@@ -24,7 +24,6 @@
 #include <iomanip>
 #include <iostream>
 #include <sstream>
-#include <vector>
 
 #include "book.h"
 #include "evaluate.h"
@@ -42,7 +41,7 @@ namespace Search {
 
   volatile SignalsType Signals;
   LimitsType Limits;
-  std::vector<Move> SearchMoves;
+  std::vector<RootMove> RootMoves;
   Position RootPosition;
 }
 
@@ -59,33 +58,6 @@ namespace {
   // Different node types, used as template parameter
   enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV };
 
-  // RootMove struct is used for moves at the root of the tree. For each root
-  // move we store a score, a node count, and a PV (really a refutation in the
-  // case of moves which fail low). Score is normally set at -VALUE_INFINITE for
-  // all non-pv moves.
-  struct RootMove {
-
-    RootMove(){}
-    RootMove(Move m) {
-      score = prevScore = -VALUE_INFINITE;
-      pv.push_back(m);
-      pv.push_back(MOVE_NONE);
-    }
-
-    bool operator<(const RootMove& m) const { return score < m.score; }
-    bool operator==(const Move& m) const { return pv[0] == m; }
-
-    void extract_pv_from_tt(Position& pos);
-    void insert_pv_in_tt(Position& pos);
-
-    Value score;
-    Value prevScore;
-    std::vector<Move> pv;
-  };
-
-
-  /// Constants
-
   // Lookup table to check if a Piece is a slider and its access function
   const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 };
   inline bool piece_is_slider(Piece p) { return Slidings[p]; }
@@ -135,17 +107,14 @@ namespace {
     return (Depth) Reductions[PvNode][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)];
   }
 
-  // Easy move margin. An easy move candidate must be at least this much
+  // Easy move margin. An easy move candidate must be at least this much better
-  // better than the second best move.
+  // than the second best move.
   const Value EasyMoveMargin = Value(0x150);
 
   // This is the minimum interval in msec between two check_time() calls
   const int TimerResolution = 5;
 
 
-  /// Namespace variables
-
-  std::vector<RootMove> RootMoves;
   size_t MultiPV, UCIMultiPV, PVIdx;
   TimeManager TimeMgr;
   int BestMoveChanges;
@@ -154,8 +123,6 @@ namespace {
   History H;
 
 
-  /// Local functions
-
   template <NodeType NT>
   Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
 
@@ -200,7 +167,7 @@ namespace {
   FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) {
 
     // Test for a pawn pushed to 7th or a passed pawn move
-    if (type_of(pos.piece_on(from_sq(m))) == PAWN)
+    if (type_of(pos.piece_moved(m)) == PAWN)
     {
         Color c = pos.side_to_move();
         if (   relative_rank(c, to_sq(m)) == RANK_7
@@ -282,29 +249,29 @@ void Search::think() {
 
   static Book book; // Defined static to initialize the PRNG only once
 
+  Move bm;
   Position& pos = RootPosition;
   Chess960 = pos.is_chess960();
   elapsed_time(true);
   TimeMgr.init(Limits, pos.startpos_ply_counter());
   TT.new_search();
   H.clear();
-  RootMoves.clear();
 
-  // Populate RootMoves with all the legal moves (default) or, if a SearchMoves
+  if (RootMoves.empty())
-  // is given, with the subset of legal moves to search.
-  for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
-      if (SearchMoves.empty() || count(SearchMoves.begin(), SearchMoves.end(), ml.move()))
-          RootMoves.push_back(RootMove(ml.move()));
-
-  if (Options["OwnBook"])
   {
-      Move bookMove = book.probe(pos, Options["Book File"], Options["Best Book Move"]);
+      cout << "info depth 0 score "
+           << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW) << endl;
 
-      if (bookMove && count(RootMoves.begin(), RootMoves.end(), bookMove))
+      RootMoves.push_back(MOVE_NONE);
-      {
-          std::swap(RootMoves[0], *find(RootMoves.begin(), RootMoves.end(), bookMove));
       goto finalize;
   }
+
+  if (   Options["OwnBook"]
+      && (bm = book.probe(pos, Options["Book File"], Options["Best Book Move"])) != MOVE_NONE
+      && count(RootMoves.begin(), RootMoves.end(), bm))
+  {
+      std::swap(RootMoves[0], *find(RootMoves.begin(), RootMoves.end(), bm));
+      goto finalize;
   }
 
   // Read UCI options: GUI could change UCI parameters during the game
@@ -375,9 +342,9 @@ void Search::think() {
 
 finalize:
 
-  // When we reach max depth we arrive here even without a StopRequest, but if
+  // When we reach max depth we arrive here even without Signals.stop is raised,
-  // we are pondering or in infinite search, we shouldn't print the best move
+  // but if we are pondering or in infinite search, we shouldn't print the best
-  // before we are told to do so.
+  // move before we are told to do so.
   if (!Signals.stop && (Limits.ponder || Limits.infinite))
       Threads.wait_for_stop_or_ponderhit();
 
@@ -406,16 +373,6 @@ namespace {
     bestValue = delta = -VALUE_INFINITE;
     ss->currentMove = MOVE_NULL; // Hack to skip update gains
 
-    // Handle the special case of a mated/stalemate position
-    if (RootMoves.empty())
-    {
-        cout << "info depth 0 score "
-             << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW) << endl;
-
-        RootMoves.push_back(MOVE_NONE);
-        return;
-    }
-
     // Iterative deepening loop until requested to stop or target depth reached
     while (!Signals.stop && ++depth <= MAX_PLY && (!Limits.maxDepth || depth <= Limits.maxDepth))
     {
@@ -531,15 +488,15 @@ namespace {
                 stop = true;
 
             // Stop search early if one move seems to be much better than others
-            if (   depth >= 10
+            if (    depth >= 12
                 && !stop
-                && (   bestMoveNeverChanged
+                && (   (bestMoveNeverChanged &&  pos.captured_piece_type())
                     || elapsed_time() > (TimeMgr.available_time() * 40) / 100))
             {
                 Value rBeta = bestValue - EasyMoveMargin;
                 (ss+1)->excludedMove = RootMoves[0].pv[0];
                 (ss+1)->skipNullMove = true;
-                Value v = search<NonPV>(pos, ss+1, rBeta - 1, rBeta, (depth * ONE_PLY) / 2);
+                Value v = search<NonPV>(pos, ss+1, rBeta - 1, rBeta, (depth - 3) * ONE_PLY);
                 (ss+1)->skipNullMove = false;
                 (ss+1)->excludedMove = MOVE_NONE;
 
@@ -701,7 +658,7 @@ namespace {
     if (   (move = (ss-1)->currentMove) != MOVE_NULL
         && (ss-1)->eval != VALUE_NONE
         && ss->eval != VALUE_NONE
-        && pos.captured_piece_type() == NO_PIECE_TYPE
+        && !pos.captured_piece_type()
         && !is_special(move))
     {
         Square to = to_sq(move);
@@ -970,7 +927,7 @@ split_point_start: // At split points actual search starts from here
           // but fixing this made program slightly weaker.
           Depth predictedDepth = newDepth - reduction<PvNode>(depth, moveCount);
           futilityValue =  futilityBase + futility_margin(predictedDepth, moveCount)
-                         + H.gain(pos.piece_on(from_sq(move)), to_sq(move));
+                         + H.gain(pos.piece_moved(move), to_sq(move));
 
           if (futilityValue < beta)
           {
@@ -1154,13 +1111,13 @@ split_point_start: // At split points actual search starts from here
 
             // Increase history value of the cut-off move
             Value bonus = Value(int(depth) * int(depth));
-            H.add(pos.piece_on(from_sq(move)), to_sq(move), bonus);
+            H.add(pos.piece_moved(move), to_sq(move), bonus);
 
             // Decrease history of all the other played non-capture moves
             for (int i = 0; i < playedMoveCount - 1; i++)
             {
                 Move m = movesSearched[i];
-                H.add(pos.piece_on(from_sq(m)), to_sq(m), -bonus);
+                H.add(pos.piece_moved(m), to_sq(m), -bonus);
             }
         }
     }
@@ -1393,7 +1350,7 @@ split_point_start: // At split points actual search starts from here
 
     from = from_sq(move);
     to = to_sq(move);
-    them = flip(pos.side_to_move());
+    them = ~pos.side_to_move();
     ksq = pos.king_square(them);
     kingAtt = pos.attacks_from<KING>(ksq);
     pc = pos.piece_on(from);
@@ -1801,13 +1758,15 @@ split_point_start: // At split points actual search starts from here
     return best;
   }
 
+} // namespace
 
-  // extract_pv_from_tt() builds a PV by adding moves from the transposition table.
-  // We consider also failing high nodes and not only VALUE_TYPE_EXACT nodes. This
-  // allow to always have a ponder move even when we fail high at root and also a
-  // long PV to print that is important for position analysis.
 
-  void RootMove::extract_pv_from_tt(Position& pos) {
+/// RootMove::extract_pv_from_tt() builds a PV by adding moves from the TT table.
+/// We consider also failing high nodes and not only VALUE_TYPE_EXACT nodes so
+/// to allow to always have a ponder move even when we fail high at root, and
+/// a long PV to print that is important for position analysis.
+
+void RootMove::extract_pv_from_tt(Position& pos) {
 
   StateInfo state[MAX_PLY_PLUS_2], *st = state;
   TTEntry* tte;
@@ -1834,14 +1793,14 @@ split_point_start: // At split points actual search starts from here
   pv.push_back(MOVE_NONE);
 
   do pos.undo_move(pv[--ply]); while (ply);
-  }
+}
 
 
-  // insert_pv_in_tt() is called at the end of a search iteration, and inserts
+/// RootMove::insert_pv_in_tt() is called at the end of a search iteration, and
-  // the PV back into the TT. This makes sure the old PV moves are searched
+/// inserts the PV back into the TT. This makes sure the old PV moves are searched
-  // first, even if the old TT entries have been overwritten.
+/// first, even if the old TT entries have been overwritten.
 
-  void RootMove::insert_pv_in_tt(Position& pos) {
+void RootMove::insert_pv_in_tt(Position& pos) {
 
   StateInfo state[MAX_PLY_PLUS_2], *st = state;
   TTEntry* tte;
@@ -1866,9 +1825,7 @@ split_point_start: // At split points actual search starts from here
   } while (pv[++ply] != MOVE_NONE);
 
   do pos.undo_move(pv[--ply]); while (ply);
-  }
+}
-
-} // namespace
 
 
 /// Thread::idle_loop() is where the thread is parked when it has no work to do.

src/search.h

@@ -48,6 +48,29 @@ struct Stack {
 };
 
 
+/// RootMove struct is used for moves at the root of the tree. For each root
+/// move we store a score, a node count, and a PV (really a refutation in the
+/// case of moves which fail low). Score is normally set at -VALUE_INFINITE for
+/// all non-pv moves.
+struct RootMove {
+
+  RootMove(){} // Needed by sort()
+  RootMove(Move m) : score(-VALUE_INFINITE), prevScore(-VALUE_INFINITE) {
+    pv.push_back(m); pv.push_back(MOVE_NONE);
+  }
+
+  bool operator<(const RootMove& m) const { return score < m.score; }
+  bool operator==(const Move& m) const { return pv[0] == m; }
+
+  void extract_pv_from_tt(Position& pos);
+  void insert_pv_in_tt(Position& pos);
+
+  Value score;
+  Value prevScore;
+  std::vector<Move> pv;
+};
+
+
 /// The LimitsType struct stores information sent by GUI about available time
 /// to search the current move, maximum depth/time, if we are in analysis mode
 /// or if we have to ponder while is our opponent's side to move.
@@ -70,13 +93,13 @@ struct SignalsType {
 
 extern volatile SignalsType Signals;
 extern LimitsType Limits;
-extern std::vector<Move> SearchMoves;
+extern std::vector<RootMove> RootMoves;
 extern Position RootPosition;
 
 extern void init();
 extern int64_t perft(Position& pos, Depth depth);
 extern void think();
 
-} // namespace
+} // namespace Search
 
 #endif // !defined(SEARCH_H_INCLUDED)

src/thread.cpp

@@ -19,6 +19,7 @@
 
 #include <iostream>
 
+#include "movegen.h"
 #include "search.h"
 #include "thread.h"
 #include "ucioption.h"
@@ -420,7 +421,7 @@ void Thread::main_loop() {
       if (do_terminate)
           return;
 
-      think(); // This is the search entry point
+      Search::think();
   }
 }
 
@@ -431,7 +432,7 @@ void Thread::main_loop() {
 // the search to finish.
 
 void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limits,
-                                    const std::vector<Move>& searchMoves, bool asyncMode) {
+                                    const std::set<Move>& searchMoves, bool async) {
   Thread& main = threads[0];
 
   lock_grab(&main.sleepLock);
@@ -443,15 +444,22 @@ void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limit
   // Copy input arguments to initialize the search
   RootPosition.copy(pos, 0);
   Limits = limits;
-  SearchMoves = searchMoves;
+  RootMoves.clear();
+
+  // Populate RootMoves with all the legal moves (default) or, if a searchMoves
+  // set is given, with the subset of legal moves to search.
+  for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
+      if (searchMoves.empty() || searchMoves.count(ml.move()))
+          RootMoves.push_back(RootMove(ml.move()));
 
   // Reset signals before to start the new search
-  memset((void*)&Signals, 0, sizeof(Signals));
+  Signals.stopOnPonderhit = Signals.firstRootMove = false;
+  Signals.stop = Signals.failedLowAtRoot = false;
 
   main.do_sleep = false;
   cond_signal(&main.sleepCond); // Wake up main thread and start searching
 
-  if (!asyncMode)
+  if (!async)
       while (!main.do_sleep)
           cond_wait(&sleepCond, &main.sleepLock);
 

src/thread.h

@@ -21,6 +21,7 @@
 #define THREAD_H_INCLUDED
 
 #include <cstring>
+#include <set>
 
 #include "lock.h"
 #include "material.h"
@@ -120,7 +121,7 @@ public:
   void wait_for_stop_or_ponderhit();
   void stop_thinking();
   void start_thinking(const Position& pos, const Search::LimitsType& limits,
-                      const std::vector<Move>& searchMoves, bool asyncMode);
+                      const std::set<Move>& = std::set<Move>(), bool async = false);
 
   template <bool Fake>
   Value split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value bestValue,

src/types.h

@@ -34,11 +34,6 @@
 /// -DUSE_POPCNT  | Add runtime support for use of popcnt asm-instruction. Works
 ///               | only in 64-bit mode. For compiling requires hardware with
 ///               | popcnt support.
-///
-/// -DOLD_LOCKS   | Under Windows are used the fast Slim Reader/Writer (SRW)
-///               | Locks and Condition Variables: these are not supported by
-///               | Windows XP and older, to compile for those platforms you
-///               | should enable OLD_LOCKS.
 
 #include <climits>
 #include <cstdlib>
@@ -339,6 +334,14 @@ extern const Value PieceValueMidgame[17];
 extern const Value PieceValueEndgame[17];
 extern int SquareDistance[64][64];
 
+inline Color operator~(Color c) {
+  return Color(c ^ 1);
+}
+
+inline Square operator~(Square s) {
+  return Square(s ^ 56);
+}
+
 inline Value mate_in(int ply) {
   return VALUE_MATE - ply;
 }
@@ -359,10 +362,6 @@ inline Color color_of(Piece p) {
   return Color(p >> 3);
 }
 
-inline Color flip(Color c) {
-  return Color(c ^ 1);
-}
-
 inline Square make_square(File f, Rank r) {
   return Square((r << 3) | f);
 }
@@ -379,10 +378,6 @@ inline Rank rank_of(Square s) {
   return Rank(s >> 3);
 }
 
-inline Square flip(Square s) {
-  return Square(s ^ 56);
-}
-
 inline Square mirror(Square s) {
   return Square(s ^ 7);
 }

src/uci.cpp

@@ -201,7 +201,7 @@ namespace {
 
     string token;
     Search::LimitsType limits;
-    std::vector<Move> searchMoves;
+    std::set<Move> searchMoves;
     int time[] = { 0, 0 }, inc[] = { 0, 0 };
 
     while (is >> token)
@@ -228,7 +228,7 @@ namespace {
             is >> limits.maxTime;
         else if (token == "searchmoves")
             while (is >> token)
-                searchMoves.push_back(move_from_uci(pos, token));
+                searchMoves.insert(move_from_uci(pos, token));
     }
 
     limits.time = time[pos.side_to_move()];