Merge branch 'master' into bishop_pin_clop

diff --git a/src/bitbase.cpp b/src/bitbase.cpp
index 700eea9892aa04819a4c27fd490bba36cd74d0a8..ef067c65bceca3bc809c5b977a8dd4610fcc4bc2 100644 (file)
--- a/src/bitbase.cpp
+++ b/src/bitbase.cpp
@@ -26,22 +26,22 @@
 namespace {
 
   // The possible pawns squares are 24, the first 4 files and ranks from 2 to 7
-  const unsigned IndexMax = 24*64*64*2; // wp_sq * wk_sq * bk_sq * stm = 196608
+  const unsigned IndexMax = 2*24*64*64; // stm * psq * wksq * bksq = 196608
 
   // Each uint32_t stores results of 32 positions, one per bit
   uint32_t KPKBitbase[IndexMax / 32];
 
   // A KPK bitbase index is an integer in [0, IndexMax] range
   //
-  // Information is mapped in this way
+  // Information is mapped in a way that minimizes number of iterations:
   //
-  // bit     0: side to move (WHITE or BLACK)
-  // bit  1- 6: black king square (from SQ_A1 to SQ_H8)
-  // bit  7-12: white king square (from SQ_A1 to SQ_H8)
+  // bit  0- 5: white king square (from SQ_A1 to SQ_H8)
+  // bit  6-11: black king square (from SQ_A1 to SQ_H8)
+  // bit    12: side to move (WHITE or BLACK)
   // bit 13-14: white pawn file (from FILE_A to FILE_D)
   // bit 15-17: white pawn 6 - rank (from 6 - RANK_7 to 6 - RANK_2)
-  unsigned index(Color stm, Square bksq, Square wksq, Square psq) {
-    return stm + (bksq << 1) + (wksq << 7) + (file_of(psq) << 13) + ((6 - rank_of(psq)) << 15);
+  unsigned index(Color us, Square bksq, Square wksq, Square psq) {
+    return wksq + (bksq << 6) + (us << 12) + (file_of(psq) << 13) + ((6 - rank_of(psq)) << 15);
   }
 
   enum Result {
@@ -55,20 +55,15 @@ namespace {
 
   struct KPKPosition {
 
-    void classify_leaf(unsigned idx);
-
-    Result classify(const std::vector<KPKPosition>& db)
-    { return stm == WHITE ? classify<WHITE>(db) : classify<BLACK>(db); }
-
     operator Result() const { return res; }
+    Result classify_leaf(unsigned idx);
+    Result classify(const std::vector<KPKPosition>& db)
+    { return us == WHITE ? classify<WHITE>(db) : classify<BLACK>(db); }
 
   private:
-    template<Color Us> Bitboard k_attacks() const
-    { return StepAttacksBB[KING][Us == WHITE ? wksq : bksq]; }
-
     template<Color Us> Result classify(const std::vector<KPKPosition>& db);
 
-    Color stm;
+    Color us;
     Square bksq, wksq, psq;
     Result res;
   };
@@ -76,12 +71,12 @@ namespace {
 } // namespace
 
 
-bool Bitbases::probe_kpk(Square wksq, Square wpsq, Square bksq, Color stm) {
+bool Bitbases::probe_kpk(Square wksq, Square wpsq, Square bksq, Color us) {
 
   assert(file_of(wpsq) <= FILE_D);
 
-  unsigned idx = index(stm, bksq, wksq, wpsq);
-  return KPKBitbase[idx / 32] & (1 << (idx & 31));
+  unsigned idx = index(us, bksq, wksq, wpsq);
+  return KPKBitbase[idx / 32] & (1 << (idx & 0x1F));
 }
 
 
@@ -94,7 +89,7 @@ void Bitbases::init_kpk() {
   for (idx = 0; idx < IndexMax; idx++)
       db[idx].classify_leaf(idx);
 
-  // Iterate until all positions are classified (26 cycles needed)
+  // Iterate until all positions are classified (15 cycles needed)
   while (repeat)
       for (repeat = idx = 0; idx < IndexMax; idx++)
           if (db[idx] == UNKNOWN && db[idx].classify(db) != UNKNOWN)
@@ -103,101 +98,61 @@ void Bitbases::init_kpk() {
   // Map 32 results into one KPKBitbase[] entry
   for (idx = 0; idx < IndexMax; idx++)
       if (db[idx] == WIN)
-          KPKBitbase[idx / 32] |= 1 << (idx & 31);
+          KPKBitbase[idx / 32] |= 1 << (idx & 0x1F);
 }
 
 
 namespace {
 
-  void KPKPosition::classify_leaf(unsigned idx) {
+  Result KPKPosition::classify_leaf(unsigned idx) {
 
-    stm  = Color(idx & 1);
-    bksq = Square((idx >> 1) & 0x3F);
-    wksq = Square((idx >> 7) & 0x3F);
+    wksq = Square((idx >> 0) & 0x3F);
+    bksq = Square((idx >> 6) & 0x3F);
+    us   = Color((idx >> 12) & 0x01);
     psq  = File((idx >> 13) & 3) | Rank(6 - (idx >> 15));
 
     // Check if two pieces are on the same square or if a king can be captured
     if (   wksq == psq || wksq == bksq || bksq == psq
-        || (k_attacks<WHITE>() & bksq)
-        || (stm == WHITE && (StepAttacksBB[PAWN][psq] & bksq)))
-        res = INVALID;
-
-    // The position is an immediate win if it is white to move and the white
-    // pawn can be promoted without getting captured.
-    else if (   rank_of(psq) == RANK_7
-             && stm == WHITE
-             && wksq != psq + DELTA_N
-             && (   square_distance(bksq, psq + DELTA_N) > 1
-                 ||(k_attacks<WHITE>() & (psq + DELTA_N))))
-        res = WIN;
-
-    // Check for known draw positions
-    //
-    // Case 1: Stalemate
-    else if (   stm == BLACK
-             && !(k_attacks<BLACK>() & ~(k_attacks<WHITE>() | StepAttacksBB[PAWN][psq])))
-        res = DRAW;
-
-    // Case 2: King can capture undefended pawn
-    else if (   stm == BLACK
-             && (k_attacks<BLACK>() & psq & ~k_attacks<WHITE>()))
-        res = DRAW;
-
-    // Case 3: Black king in front of white pawn
-    else if (   bksq == psq + DELTA_N
-             && rank_of(psq) < RANK_7)
-        res = DRAW;
-
-    // Case 4: White king in front of pawn and black has opposition
-    else if (   stm == WHITE
-             && wksq == psq + DELTA_N
-             && bksq == wksq + DELTA_N + DELTA_N
-             && rank_of(psq) < RANK_5)
-        res = DRAW;
-
-    // Case 5: Stalemate with rook pawn
-    else if (   bksq == SQ_A8
-             && file_of(psq) == FILE_A)
-        res = DRAW;
-
-    // Case 6: White king trapped on the rook file
-    else if (   file_of(wksq) == FILE_A
-             && file_of(psq) == FILE_A
-             && rank_of(wksq) > rank_of(psq)
-             && bksq == wksq + 2)
-        res = DRAW;
+        || (StepAttacksBB[KING][wksq] & bksq)
+        || (us == WHITE && (StepAttacksBB[PAWN][psq] & bksq)))
+        return res = INVALID;
 
-    else
-        res = UNKNOWN;
+    if (us == WHITE)
+    {
+        // Immediate win if pawn can be promoted without getting captured
+        if (   rank_of(psq) == RANK_7
+            && wksq != psq + DELTA_N
+            && (   square_distance(bksq, psq + DELTA_N) > 1
+                ||(StepAttacksBB[KING][wksq] & (psq + DELTA_N))))
+            return res = WIN;
+    }
+    // Immediate draw if is stalemate or king captures undefended pawn
+    else if (  !(StepAttacksBB[KING][bksq] & ~(StepAttacksBB[KING][wksq] | StepAttacksBB[PAWN][psq]))
+             || (StepAttacksBB[KING][bksq] & psq & ~StepAttacksBB[KING][wksq]))
+        return res = DRAW;
+
+    return res = UNKNOWN;
   }
 
   template<Color Us>
   Result KPKPosition::classify(const std::vector<KPKPosition>& db) {
 
-    // White to Move: If one move leads to a position classified as RESULT_WIN,
-    // the result of the current position is RESULT_WIN. If all moves lead to
-    // positions classified as RESULT_DRAW, the current position is classified
-    // RESULT_DRAW otherwise the current position is classified as RESULT_UNKNOWN.
+    // White to Move: If one move leads to a position classified as WIN, the result
+    // of the current position is WIN. If all moves lead to positions classified
+    // as DRAW, the current position is classified DRAW otherwise the current
+    // position is classified as UNKNOWN.
     //
-    // Black to Move: If one move leads to a position classified as RESULT_DRAW,
-    // the result of the current position is RESULT_DRAW. If all moves lead to
-    // positions classified as RESULT_WIN, the position is classified RESULT_WIN.
-    // Otherwise, the current position is classified as RESULT_UNKNOWN.
+    // Black to Move: If one move leads to a position classified as DRAW, the result
+    // of the current position is DRAW. If all moves lead to positions classified
+    // as WIN, the position is classified WIN otherwise the current position is
+    // classified UNKNOWN.
 
     Result r = INVALID;
-    Bitboard b = k_attacks<Us>();
+    Bitboard b = StepAttacksBB[KING][Us == WHITE ? wksq : bksq];
 
     while (b)
-    {
-        r |= Us == WHITE ? db[index(BLACK, bksq, pop_lsb(&b), psq)]
-                         : db[index(WHITE, pop_lsb(&b), wksq, psq)];
-
-        if (Us == WHITE && (r & WIN))
-            return res = WIN;
-
-        if (Us == BLACK && (r & DRAW))
-            return res = DRAW;
-    }
+        r |= Us == WHITE ? db[index(~Us, bksq, pop_lsb(&b), psq)]
+                         : db[index(~Us, pop_lsb(&b), wksq, psq)];
 
     if (Us == WHITE && rank_of(psq) < RANK_7)
     {
@@ -206,12 +161,12 @@ namespace {
 
         if (rank_of(s) == RANK_3 && s != wksq && s != bksq)
             r |= db[index(BLACK, bksq, wksq, s + DELTA_N)]; // Double push
-
-        if (r & WIN)
-            return res = WIN;
     }
 
-    return res = r & UNKNOWN ? UNKNOWN : Us == WHITE ? DRAW : WIN;
+    if (Us == WHITE)
+        return res = r & WIN  ? WIN  : r & UNKNOWN ? UNKNOWN : DRAW;
+    else
+        return res = r & DRAW ? DRAW : r & UNKNOWN ? UNKNOWN : WIN;
   }
 
-}
+} // namespace

diff --git a/src/bitboard.h b/src/bitboard.h
index e3331bd440784c1e2bdec3154012c6f03d2a2c9f..90dec8165678811ae71f8efce50e11bbf400a5c6 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -33,7 +33,7 @@ void print(Bitboard b);
 namespace Bitbases {
 
 void init_kpk();
-bool probe_kpk(Square wksq, Square wpsq, Square bksq, Color stm);
+bool probe_kpk(Square wksq, Square wpsq, Square bksq, Color us);
 
 }
 

diff --git a/src/endgame.cpp b/src/endgame.cpp
index ae29a71aba07d0faa77847e7045a31f1ef92b58c..8591676305f434ef8c10716058624d70d3dc32c5 100644 (file)
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -199,21 +199,21 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
   assert(pos.piece_count(weakerSide, PAWN) == 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();
+      us   = pos.side_to_move();
   }
   else
   {
       wksq = ~pos.king_square(BLACK);
       bksq = ~pos.king_square(WHITE);
       wpsq = ~pos.piece_list(BLACK, PAWN)[0];
-      stm  = ~pos.side_to_move();
+      us   = ~pos.side_to_move();
   }
 
   if (file_of(wpsq) >= FILE_E)
@@ -223,7 +223,7 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
       wpsq = mirror(wpsq);
   }
 
-  if (!Bitbases::probe_kpk(wksq, wpsq, bksq, stm))
+  if (!Bitbases::probe_kpk(wksq, wpsq, bksq, us))
       return VALUE_DRAW;
 
   Value result = VALUE_KNOWN_WIN + PawnValueEg + Value(rank_of(wpsq));
@@ -920,14 +920,14 @@ ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
   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();
+  Color us = pos.side_to_move();
 
   if (strongerSide == BLACK)
   {
       wksq = ~wksq;
       bksq = ~bksq;
       wpsq = ~wpsq;
-      stm  = ~stm;
+      us   = ~us;
   }
 
   if (file_of(wpsq) >= FILE_E)
@@ -945,5 +945,5 @@ 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 Bitbases::probe_kpk(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
+  return Bitbases::probe_kpk(wksq, wpsq, bksq, us) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
 }

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index e17a3e340b939206662d259d8f58a42259585708..02810b78490093f1f14f7c220897f2661f4bc63f 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -498,7 +498,7 @@ Value do_evaluate(const Position& pos, Value& margin) {
 
     // Init king safety tables only if we are going to use them
     if (   pos.piece_count(Us, QUEEN)
-        && pos.non_pawn_material(Us) >= QueenValueMg + RookValueMg)
+        && pos.non_pawn_material(Us) > QueenValueMg + PawnValueMg)
     {
         ei.kingRing[Them] = (b | (Us == WHITE ? b >> 8 : b << 8));
         b &= ei.attackedBy[Us][PAWN];

diff --git a/src/position.cpp b/src/position.cpp
index ad0a621de0b954ce9078aedd0caf860bbcc93473..a51383f0d4eed8c2c9c08d318a6f422c743102a1 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -278,11 +278,11 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) {
   }
 
   // 5-6. Halfmove clock and fullmove number
-  ss >> std::skipws >> st->rule50 >> startPosPly;
+  ss >> std::skipws >> st->rule50 >> gamePly;
 
   // Convert from fullmove starting from 1 to ply starting from 0,
   // handle also common incorrect FEN with fullmove = 0.
-  startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
+  gamePly = std::max(2 * (gamePly - 1), 0) + int(sideToMove == BLACK);
 
   st->key = compute_key();
   st->pawnKey = compute_pawn_key();
@@ -373,7 +373,7 @@ const string Position::fen() const {
       ss << '-';
 
   ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
-      << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
+      << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2;
 
   return ss.str();
 }
@@ -735,8 +735,9 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
   // Update side to move
   k ^= Zobrist::side;
 
-  // Increment the 50 moves rule draw counter. Resetting it to zero in the
-  // case of a capture or a pawn move is taken care of later.
+  // Increment ply counters.In particular rule50 will be later reset it to zero
+  // in case of a capture or a pawn move.
+  gamePly++;
   st->rule50++;
   st->pliesFromNull++;
 
@@ -1054,6 +1055,7 @@ void Position::undo_move(Move m) {
 
   // Finally point our state pointer back to the previous state
   st = st->previous;
+  gamePly--;
 
   assert(pos_is_ok());
 }
@@ -1417,7 +1419,7 @@ void Position::flip() {
   thisThread = pos.this_thread();
   nodes = pos.nodes_searched();
   chess960 = pos.is_chess960();
-  startPosPly = pos.startpos_ply_counter();
+  gamePly = pos.game_ply();
 
   for (Square s = SQ_A1; s <= SQ_H8; s++)
       if (!pos.is_empty(s))

diff --git a/src/position.h b/src/position.h
index 579b5308a82e6bea721cdec7ff5233a6a7b6ae93..fb7eb4b90cc79335ade326bcbeae0d59825c1fe6 100644 (file)
--- a/src/position.h
+++ b/src/position.h
@@ -174,7 +174,7 @@ public:
 
   // Other properties of the position
   Color side_to_move() const;
-  int startpos_ply_counter() const;
+  int game_ply() const;
   bool is_chess960() const;
   Thread* this_thread() const;
   int64_t nodes_searched() const;
@@ -218,7 +218,7 @@ private:
   Bitboard castlePath[COLOR_NB][CASTLING_SIDE_NB];
   StateInfo startState;
   int64_t nodes;
-  int startPosPly;
+  int gamePly;
   Color sideToMove;
   Thread* thisThread;
   StateInfo* st;
@@ -376,8 +376,8 @@ inline bool Position::is_passed_pawn_push(Move m) const {
         && pawn_is_passed(sideToMove, to_sq(m));
 }
 
-inline int Position::startpos_ply_counter() const {
-  return startPosPly + st->pliesFromNull; // HACK
+inline int Position::game_ply() const {
+  return gamePly;
 }
 
 inline bool Position::opposite_bishops() const {

diff --git a/src/search.cpp b/src/search.cpp
index 74dc9e29bdb4f2fafa53eb95a1b208413d2bfa45..b9cbb956d823b9cb7bb30605bdd3524f46d608c2 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -182,7 +182,7 @@ void Search::think() {
   static PolyglotBook book; // Defined static to initialize the PRNG only once
 
   RootColor = RootPos.side_to_move();
-  TimeMgr.init(Limits, RootPos.startpos_ply_counter(), RootColor);
+  TimeMgr.init(Limits, RootPos.game_ply(), RootColor);
 
   if (RootMoves.empty())
   {