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);
-          nodes += RootPosition.nodes_searched();
+          Threads.start_thinking(pos, limits);
+          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 RookPseudoAttacks[64];
-Bitboard QueenPseudoAttacks[64];
+Bitboard PseudoAttacks[6][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);
-      RookPseudoAttacks[s]   = rook_attacks_bb(s, 0);
-      QueenPseudoAttacks[s]  = queen_attacks_bb(s, 0);
+      PseudoAttacks[BISHOP][s] = bishop_attacks_bb(s, 0);
+      PseudoAttacks[ROOK][s]   = rook_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 RookPseudoAttacks[64];
-extern Bitboard QueenPseudoAttacks[64];
+extern Bitboard PseudoAttacks[6][64];
 
 extern uint8_t BitCount8Bit[256];
 

src/book.cpp

@@ -17,13 +17,13 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-
 /*
   The code in this file is based on the opening book code in PolyGlot
   by Fabien Letouzey. PolyGlot is available under the GNU General
   Public License, and can be downloaded from http://wbec-ridderkerk.nl
 */
 
+#include <algorithm>
 #include <cassert>
 #include <iostream>
 
@@ -306,225 +306,182 @@ namespace {
   const Key* ZobEnPassant = PolyGlotRandoms + 772;
   const Key* ZobTurn      = PolyGlotRandoms + 780;
 
-  // Piece offset is calculated as 64 * (PolyPiece ^ 1) where
-  // PolyPiece is: BP = 0, WP = 1, BN = 2, WN = 3 ... BK = 10, WK = 11
-  const int PieceOfs[] = { 0, 64, 192, 320, 448, 576, 704, 0,
+  // PieceOffset is calculated as 64 * (PolyPiece ^ 1) where PolyPiece
+  // is: BP = 0, WP = 1, BN = 2, WN = 3 ... BK = 10, WK = 11
+  const int PieceOffset[] = { 0, 64, 192, 320, 448, 576, 704, 0,
                               0,  0, 128, 256, 384, 512, 640 };
 
-  // book_key() builds up a PolyGlot hash key out of a position
+  // book_key() returns the PolyGlot hash key of the given position
   uint64_t book_key(const Position& pos) {
 
-    uint64_t result = 0;
+    uint64_t key = 0;
     Bitboard b = pos.occupied_squares();
 
     while (b)
     {
         Square s = pop_1st_bit(&b);
-        result ^= ZobPiece[PieceOfs[pos.piece_on(s)] + s];
+        key ^= ZobPiece[PieceOffset[pos.piece_on(s)] + s];
     }
 
-    if (pos.can_castle(WHITE_OO))
-        result ^= ZobCastle[0];
+    b =  (pos.can_castle(WHITE_OO) << 0) | (pos.can_castle(WHITE_OOO) << 1)
+       | (pos.can_castle(BLACK_OO) << 2) | (pos.can_castle(BLACK_OOO) << 3);
 
-    if (pos.can_castle(WHITE_OOO))
-        result ^= ZobCastle[1];
-
-    if (pos.can_castle(BLACK_OO))
-        result ^= ZobCastle[2];
-
-    if (pos.can_castle(BLACK_OOO))
-        result ^= ZobCastle[3];
+    while (b)
+        key ^= ZobCastle[pop_1st_bit(&b)];
 
     if (pos.ep_square() != SQ_NONE)
-        result ^= ZobEnPassant[file_of(pos.ep_square())];
+        key ^= ZobEnPassant[file_of(pos.ep_square())];
 
     if (pos.side_to_move() == WHITE)
-        result ^= ZobTurn[0];
+        key ^= ZobTurn[0];
 
-    return result;
-  }
+    return key;
   }
 
+} // namespace
 
-/// Book c'tor. Make random number generation less deterministic, for book moves
-Book::Book() : bookSize(0) {
+Book::Book() : size(0) {
 
   for (int i = abs(system_time() % 10000); i > 0; i--)
-      RKiss.rand<unsigned>();
+      RKiss.rand<unsigned>(); // Make random number generation less deterministic
+}
+
+Book::~Book() { if (is_open()) close(); }
+
+
+/// Book::operator>>() reads sizeof(T) chars from the file's binary byte stream
+/// and converts them in a number of type T. A Polyglot book stores numbers in
+/// big-endian format.
+
+template<typename T> Book& Book::operator>>(T& n) {
+
+  n = 0;
+  for (size_t i = 0; i < sizeof(T); i++)
+      n = T((n << 8) + ifstream::get());
+
+  return *this;
+}
+
+template<> Book& Book::operator>>(BookEntry& e) {
+  return *this >> e.key >> e.move >> e.count >> e.learn;
 }
 
 
-/// Book destructor. Be sure file is closed before we leave.
+/// Book::open() tries to open a book file with the given name after closing
+/// any exsisting one.
 
-Book::~Book() {
+bool Book::open(const char* fName) {
 
-  close();
-}
+  fileName = "";
 
-
-/// Book::close() closes the file only if it is open, otherwise the call fails
-/// and the failbit internal state flag is set.
-
-void Book::close() {
-
-  if (bookFile.is_open())
-      bookFile.close();
-
-  bookName = "";
-  bookSize = 0;
-}
-
-
-/// Book::open() opens a book file with a given name
-
-void Book::open(const string& fileName) {
-
-  // Close old file before opening the new
+  if (is_open()) // Cannot close an already closed file
       close();
 
-  bookFile.open(fileName.c_str(), ifstream::in | ifstream::binary |ios::ate);
+  ifstream::open(fName, ifstream::in | ifstream::binary | ios::ate);
 
-  // Silently return when asked to open a non-exsistent file
-  if (!bookFile.is_open())
-      return;
+  if (!is_open())
+      return false; // Silently fail if the file is not found
 
-  // Get the book size in number of entries, we are already at the file end
-  bookSize = long(bookFile.tellg()) / sizeof(BookEntry);
+  // Get the book size in number of entries, we are already at the end of file
+  size = tellg() / sizeof(BookEntry);
 
-  if (!bookFile.good())
+  if (!good())
   {
-      cerr << "Failed to open book file " << fileName << endl;
+      cerr << "Failed to open book file " << fName << endl;
       exit(EXIT_FAILURE);
   }
 
-  // Set only if successful
-  bookName = fileName;
+  fileName = fName; // Set only if successful
+  return true;
 }
 
 
-/// Book::probe() gets a book move for a given position. Returns MOVE_NONE
-/// if no book move is found. If findBest is true then returns always the
-/// highest rated move otherwise chooses randomly based on the move score.
+/// Book::probe() tries to find a book move for the given position. If no move
+/// is found returns MOVE_NONE. If pickBest is true returns always the highest
+/// rated move, otherwise randomly chooses one, based on the move score.
 
-Move Book::probe(const Position& pos, bool findBest) {
+Move Book::probe(const Position& pos, const string& fName, bool pickBest) {
 
-  if (!bookSize || !bookFile.is_open())
+  BookEntry e;
+  uint16_t best = 0;
+  unsigned sum = 0;
+  Move move = MOVE_NONE;
+  uint64_t key = book_key(pos);
+
+  if (fileName != fName && !open(fName.c_str()))
       return MOVE_NONE;
 
-  BookEntry entry;
-  unsigned scoresSum = 0, bestScore = 0, bookMove = 0;
-  uint64_t key = book_key(pos);
-  int idx = first_entry(key) - 1;
+  binary_search(key);
 
-  // Choose a book move among the possible moves for the given position
-  while (++idx < bookSize && (entry = read_entry(idx), entry.key == key))
+  while (*this >> e, e.key == key && good())
   {
-      scoresSum += entry.count;
+      best = max(best, e.count);
+      sum += e.count;
 
       // Choose book move according to its score. If a move has a very
       // high score it has higher probability to be choosen than a move
       // with lower score. Note that first entry is always chosen.
-      if (   RKiss.rand<unsigned>() % scoresSum < entry.count
-          || (findBest && entry.count > bestScore))
-          bookMove = entry.move;
-
-      if (entry.count > bestScore)
-          bestScore = entry.count;
+      if (   (RKiss.rand<unsigned>() % sum < e.count)
+          || (pickBest && e.count == best))
+          move = Move(e.move);
   }
 
-  if (!bookMove)
+  if (!move)
       return MOVE_NONE;
 
   // A PolyGlot book move is encoded as follows:
   //
   // bit  0- 5: destination square (from 0 to 63)
   // bit  6-11: origin square (from 0 to 63)
-  // bit 12-13-14: promotion piece (from KNIGHT == 1 to QUEEN == 4)
+  // bit 12-14: promotion piece (from KNIGHT == 1 to QUEEN == 4)
   //
-  // Castling moves follow "king captures rook" representation. So in case
-  // book move is a promotion we have to convert to our representation, in
-  // all other cases we can directly compare with a Move after having
-  // masked out special Move's flags that are not supported by PolyGlot.
-  int promotion = (bookMove >> 12) & 7;
+  // Castling moves follow "king captures rook" representation. So in case book
+  // move is a promotion we have to convert to our representation, in all the
+  // other cases we can directly compare with a Move after having masked out
+  // the special Move's flags (bit 14-15) that are not supported by PolyGlot.
+  int pt = (move >> 12) & 7;
+  if (pt)
+      move = make_promotion(from_sq(move), to_sq(move), PieceType(pt + 1));
 
-  if (promotion)
-      bookMove = make_promotion_move(move_from(Move(bookMove)),
-                                     move_to(Move(bookMove)),
-                                     PieceType(promotion + 1));
-  // Verify the book move is legal
+  // Add 'special move' flags and verify it is legal
   for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
-      if (unsigned(ml.move() & ~(3 << 14)) == bookMove) // Mask out special flags
+      if (move == (ml.move() & 0x3FFF))
           return ml.move();
 
   return MOVE_NONE;
 }
 
 
-/// Book::first_entry() takes a book key as input, and does a binary search
-/// through the book file for the given key. The index to the first (leftmost)
-/// book entry with the same key as the input is returned. When the key is not
-/// found in the book file, bookSize is returned.
+/// Book::binary_search() takes a book key as input, and does a binary search
+/// through the book file for the given key. File stream current position is set
+/// to the leftmost book entry with the same key as the input.
 
-int Book::first_entry(uint64_t key) {
-
-  int left, right, mid;
-
-  // Binary search (finds the leftmost entry with given key)
-  left = 0;
-  right = bookSize - 1;
-
-  assert(left <= right);
-
-  while (left < right)
-  {
-      mid = (left + right) / 2;
-
-      assert(mid >= left && mid < right);
-
-      if (key <= read_entry(mid).key)
-          right = mid;
-      else
-          left = mid + 1;
-  }
-
-  assert(left == right);
-
-  return read_entry(left).key == key ? left : bookSize;
-}
-
-
-/// Book::operator>>() reads sizeof(T) chars from the file's binary byte
-/// stream and converts them in a number of type T.
-template<typename T>
-Book& Book::operator>>(T& n) {
-
-  n = 0;
-
-  for (size_t i = 0; i < sizeof(T); i++)
-      n = T((n << 8) + bookFile.get());
-
-  return *this;
-}
-
-
-/// Book::read_entry() takes an integer index, and returns the BookEntry
-/// at the given index in the book file.
-
-BookEntry Book::read_entry(int idx) {
-
-  assert(idx >= 0 && idx < bookSize);
-  assert(bookFile.is_open());
+void Book::binary_search(uint64_t key) {
 
+  size_t low, high, mid;
   BookEntry e;
 
-  bookFile.seekg(idx * sizeof(BookEntry), ios_base::beg);
+  low = 0;
+  high = size - 1;
 
-  *this >> e.key >> e.move >> e.count >> e.learn;
+  assert(low <= high);
 
-  if (!bookFile.good())
+  while (low < high && good())
   {
-      cerr << "Failed to read book entry at index " << idx << endl;
-      exit(EXIT_FAILURE);
+      mid = (low + high) / 2;
+
+      assert(mid >= low && mid < high);
+
+      seekg(mid * sizeof(BookEntry), ios_base::beg);
+      *this >> e;
+
+      if (key <= e.key)
+          high = mid;
+      else
+          low = mid + 1;
   }
-  return e;
+
+  assert(low == high);
+
+  seekg(low * sizeof(BookEntry), ios_base::beg);
 }

src/book.h

@@ -37,25 +37,22 @@ struct BookEntry {
   uint32_t learn;
 };
 
-class Book {
+
+class Book : private std::ifstream {
 public:
   Book();
   ~Book();
-  void open(const std::string& fileName);
-  void close();
-  Move probe(const Position& pos, bool findBestMove);
-  const std::string name() const { return bookName; }
+  Move probe(const Position& pos, const std::string& fName, bool pickBest);
 
 private:
   template<typename T> Book& operator>>(T& n);
 
-  BookEntry read_entry(int idx);
-  int first_entry(uint64_t key);
+  bool open(const char* fName);
+  void binary_search(uint64_t key);
 
   RKISS RKiss;
-  std::ifstream bookFile;
-  std::string bookName;
-  int bookSize;
+  std::string fileName;
+  size_t size;
 };
 
 #endif // !defined(BOOK_H_INCLUDED)

src/endgame.cpp

@@ -205,10 +205,10 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
   }
   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.piece_list(BLACK, PAWN)[0];
+      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);
-      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);
@@ -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);
-      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)
   {
@@ -867,10 +867,10 @@ ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
 
   if (strongerSide == BLACK)
   {
-      wksq = flip(wksq);
-      bksq = flip(bksq);
-      wpsq = flip(wpsq);
-      stm = flip(stm);
+      wksq = ~wksq;
+      bksq = ~bksq;
+      wpsq = ~wpsq;
+      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
-#if !defined(OLD_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
-
+// We use critical sections on Windows to support Windows XP and older versions,
+// unfortunatly cond_wait() is racy between lock_release() and WaitForSingleObject()
+// but apart from this they have the same speed performance of SRW locks.
 typedef CRITICAL_SECTION Lock;
 typedef HANDLE WaitCondition;
 
@@ -75,10 +58,8 @@ typedef HANDLE WaitCondition;
 #  define cond_init(x) { *x = CreateEvent(0, FALSE, FALSE, 0); }
 #  define cond_destroy(x) CloseHandle(*x)
 #  define cond_signal(x) SetEvent(*x)
-#  define cond_wait(x,y) { ResetEvent(*x); lock_release(y); WaitForSingleObject(*x, INFINITE); lock_grab(y); }
-#  define cond_timedwait(x,y,z) { ResetEvent(*x); lock_release(y); WaitForSingleObject(*x,z); lock_grab(y); }
-
-#endif
+#  define cond_wait(x,y) { lock_release(y); WaitForSingleObject(*x, INFINITE); lock_grab(y); }
+#  define cond_timedwait(x,y,z) { lock_release(y); WaitForSingleObject(*x,z); lock_grab(y); }
 
 #endif
 

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";
+static const string Version = "2.2.2";
 static const string Tag = "";
 
 

src/move.cpp

@@ -33,8 +33,8 @@ using std::string;
 
 const string move_to_uci(Move m, bool chess960) {
 
-  Square from = move_from(m);
-  Square to = move_to(m);
+  Square from = from_sq(m);
+  Square to = to_sq(m);
   string promotion;
 
   if (m == MOVE_NONE)
@@ -83,13 +83,13 @@ const string move_to_san(Position& pos, Move m) {
 
   Bitboard attackers;
   bool ambiguousMove, ambiguousFile, ambiguousRank;
-  Square sq, from = move_from(m);
-  Square to = move_to(m);
+  Square sq, from = from_sq(m);
+  Square to = to_sq(m);
   PieceType pt = type_of(pos.piece_on(from));
   string san;
 
   if (is_castle(m))
-      san = (move_to(m) < move_from(m) ? "O-O-O" : "O-O");
+      san = (to_sq(m) < from_sq(m) ? "O-O-O" : "O-O");
   else
   {
       if (pt != PAWN)
@@ -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
-  // because we need to test for a mate after the move is done.
+  if (pos.move_gives_check(m, CheckInfo(pos)))
+  {
       StateInfo st;
       pos.do_move(m, st);
-  if (pos.in_check())
-      san += pos.is_mate() ? "#" : "+";
+      san += MoveList<MV_LEGAL>(pos).size() ? "+" : "#";
       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,
-// hardcoded list name 'mlist' and from square 'from'.
-#define SERIALIZE_MOVES(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); }
+/// Simple macro to wrap a very common while loop, no facny, no flexibility,
+/// hardcoded names 'mlist' and 'from'.
+#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_PAWNS(b, d) while (b) { Square to = pop_1st_bit(&b); \
+                                         (*mlist++).move = make_move(to + (d), to); }
 namespace {
 
-  enum CastlingSide {
-    KING_SIDE,
-    QUEEN_SIDE
-  };
+  enum CastlingSide { KING_SIDE, QUEEN_SIDE };
 
-  template<CastlingSide>
-  MoveStack* generate_castle_moves(const Position&, MoveStack*, Color us);
+  template<CastlingSide Side, bool OnlyChecks>
+  MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist, Color us) {
 
-  template<Color, MoveType>
-  MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard, Square);
+    const CastleRight CR[] = { Side ? WHITE_OOO : WHITE_OO,
+                               Side ? BLACK_OOO : BLACK_OO };
 
-  template<PieceType Pt>
-  inline MoveStack* generate_discovered_checks(const Position& pos, MoveStack* mlist, Square from) {
+    if (!pos.can_castle(CR[us]))
+        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)
-        b &= ~QueenPseudoAttacks[pos.king_square(flip(pos.side_to_move()))];
+    // 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(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,
-                                           Bitboard dc, Square ksq) {
+  inline MoveStack* generate_direct_checks(const Position& pos, MoveStack* mlist,
+                                           Color us, const CheckInfo& ci) {
     assert(Pt != KING && Pt != PAWN);
 
     Bitboard checkSqs, b;
@@ -70,43 +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))
-            || (Pt == ROOK   && !(RookPseudoAttacks[from]   & checkSqs))
-            || (Pt == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
+        if (    (Pt == BISHOP || Pt == ROOK || Pt == QUEEN)
+            && !(PseudoAttacks[Pt][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)
-                        : generate_pawn_moves<BLACK, MV_CHECK>(p, m, dc, ksq));
+  template<>
+  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);
-    assert(Type == MV_CAPTURE || Type == MV_NON_CAPTURE || Type == MV_EVASION);
-
-    return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m, t, SQ_NONE)
-                        : generate_pawn_moves<BLACK, 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);
   }
 
+
   template<PieceType Pt>
   FORCE_INLINE MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
 
@@ -119,24 +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);
-
-    b = pos.attacks_from<KING>(from) & target;
-    SERIALIZE_MOVES(b);
+    Bitboard b = pos.attacks_from<KING>(from) & target;
+    SERIALIZE(b);
     return mlist;
   }
 
-}
+} // namespace
 
 
 /// generate<MV_CAPTURE> generates all pseudo-legal captures and queen
@@ -151,27 +339,22 @@ namespace {
 template<MoveType Type>
 MoveStack* generate(const Position& pos, MoveStack* mlist) {
 
+  assert(Type == MV_CAPTURE || Type == MV_NON_CAPTURE || Type == MV_NON_EVASION);
   assert(!pos.in_check());
 
   Color us = pos.side_to_move();
   Bitboard target;
 
-  if (Type == MV_CAPTURE || Type == MV_NON_EVASION)
-      target = pos.pieces(flip(us));
+  if (Type == MV_CAPTURE)
+      target = pos.pieces(~us);
+
   else if (Type == MV_NON_CAPTURE)
       target = pos.empty_squares();
-  else
-      assert(false);
 
-  if (Type == MV_NON_EVASION)
-  {
-      mlist = generate_piece_moves<PAWN, MV_CAPTURE>(pos, mlist, us, target);
-      mlist = generate_piece_moves<PAWN, MV_NON_CAPTURE>(pos, mlist, us, pos.empty_squares());
-      target |= pos.empty_squares();
-  }
-  else
+  else if (Type == MV_NON_EVASION)
+      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);
   mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
   mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
@@ -180,11 +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>(pos, mlist, us);
-
-      if (pos.can_castle(us == WHITE ? WHITE_OOO : BLACK_OOO))
-          mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist, us);
+      mlist = generate_castle_moves<KING_SIDE, false>(pos, mlist, us);
+      mlist = generate_castle_moves<QUEEN_SIDE, false>(pos, mlist, us);
   }
 
   return mlist;
@@ -203,36 +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));
-
-  // Discovered non-capture checks
-  b = dc = pos.discovered_check_candidates();
-
-  while (b)
+  while (dc)
   {
-     from = pop_1st_bit(&b);
-     switch (type_of(pos.piece_on(from)))
-     {
-      case PAWN:   /* Will be generated togheter with pawns direct checks */     break;
-      case KNIGHT: mlist = generate_discovered_checks<KNIGHT>(pos, mlist, from); break;
-      case BISHOP: mlist = generate_discovered_checks<BISHOP>(pos, mlist, from); break;
-      case ROOK:   mlist = generate_discovered_checks<ROOK>(pos, mlist, from);   break;
-      case KING:   mlist = generate_discovered_checks<KING>(pos, mlist, from);   break;
-      default: assert(false); break;
-     }
+     Square from = pop_1st_bit(&dc);
+     PieceType pt = type_of(pos.piece_on(from));
+
+     if (pt == PAWN)
+         continue; // Will be generated togheter with direct checks
+
+     Bitboard b = pos.attacks_from(Piece(pt), from) & pos.empty_squares();
+
+     if (pt == KING)
+         b &= ~PseudoAttacks[QUEEN][ci.ksq];
+
+     SERIALIZE(b);
   }
 
-  // Direct non-capture checks
-  mlist = generate_direct_checks<PAWN>(pos, mlist, us, dc, ksq);
-  mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, dc, ksq);
-  mlist = generate_direct_checks<BISHOP>(pos, mlist, us, dc, ksq);
-  mlist = generate_direct_checks<ROOK>(pos, mlist, us, dc, ksq);
-  return  generate_direct_checks<QUEEN>(pos, mlist, us, dc, ksq);
+  mlist = generate_direct_checks<PAWN>(pos, mlist, us, ci);
+  mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, ci);
+  mlist = generate_direct_checks<BISHOP>(pos, mlist, us, ci);
+  mlist = generate_direct_checks<ROOK>(pos, mlist, us, ci);
+  mlist = generate_direct_checks<QUEEN>(pos, mlist, us, ci);
+
+  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;
 }
 
 
@@ -248,38 +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
-  // them from the king evasions set so to early skip known
-  // illegal moves and avoid an useless legality check later.
+  // Find squares attacked by slider checkers, we will remove them from the king
+  // evasions so to skip known illegal moves avoiding 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 ROOK:   sliderAttacks |= RookPseudoAttacks[checksq];   break;
+      case BISHOP: sliderAttacks |= PseudoAttacks[BISHOP][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
-          // in the other direction becuase are not reachable by the king anyway.
-          if (squares_between(ksq, checksq) || (RookPseudoAttacks[checksq] & (1ULL << ksq)))
-              sliderAttacks |= QueenPseudoAttacks[checksq];
+          // If queen and king are far or not on a diagonal line we can safely
+          // remove all the squares attacked in the other direction becuase are
+          // not reachable by the king anyway.
+          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
-          // use real rook attacks to check if king is safe to move in the other direction.
-          // For example: king in B2, queen in A1 a knight in B1, and we can safely move to C1.
+          // Otherwise we need to use real rook attacks to check if king is safe
+          // to move in the other direction. For example: king in B2, queen in A1
+          // 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;
@@ -289,14 +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
-  // checker piece is possible.
+  // Blocking evasions or captures of the checking piece
   target = squares_between(checksq, ksq) | checkers;
 
   mlist = generate_piece_moves<PAWN, MV_EVASION>(pos, mlist, us, target);
@@ -307,7 +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) {
@@ -317,8 +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;
@@ -327,217 +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<MoveType Type, 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)
-            (*mlist++).move = make_promotion_move(to - Delta, to, QUEEN);
-
-        if (Type == MV_NON_CAPTURE || Type == MV_EVASION)
-        {
-            (*mlist++).move = make_promotion_move(to - Delta, to, ROOK);
-            (*mlist++).move = make_promotion_move(to - Delta, to, BISHOP);
-            (*mlist++).move = make_promotion_move(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_move(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)
-    {
-        mlist = generate_pawn_captures<Type, RIGHT_UP>(mlist, pawns, enemyPieces);
-        mlist = generate_pawn_captures<Type, 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) && 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_move(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_move(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

@@ -254,8 +254,8 @@ void MovePicker::score_captures() {
   for (MoveStack* cur = moves; cur != lastMove; cur++)
   {
       m = cur->move;
-      cur->score =  PieceValueMidgame[pos.piece_on(move_to(m))]
-                  - type_of(pos.piece_on(move_from(m)));
+      cur->score =  PieceValueMidgame[pos.piece_on(to_sq(m))]
+                  - type_of(pos.piece_moved(m));
 
       if (is_promotion(m))
           cur->score += PieceValueMidgame[Piece(promotion_piece_type(m))];
@@ -270,8 +270,8 @@ void MovePicker::score_noncaptures() {
   for (MoveStack* cur = moves; cur != lastMove; cur++)
   {
       m = cur->move;
-      from = move_from(m);
-      cur->score = H.value(pos.piece_on(from), move_to(m));
+      from = from_sq(m);
+      cur->score = H.value(pos.piece_on(from), to_sq(m));
   }
 }
 
@@ -293,10 +293,10 @@ void MovePicker::score_evasions() {
       if ((seeScore = pos.see_sign(m)) < 0)
           cur->score = seeScore - History::MaxValue; // Be sure we are at the bottom
       else if (pos.is_capture(m))
-          cur->score =  PieceValueMidgame[pos.piece_on(move_to(m))]
-                      - type_of(pos.piece_on(move_from(m))) + History::MaxValue;
+          cur->score =  PieceValueMidgame[pos.piece_on(to_sq(m))]
+                      - type_of(pos.piece_moved(m)) + History::MaxValue;
       else
-          cur->score = H.value(pos.piece_on(move_from(m)), move_to(m));
+          cur->score = H.value(pos.piece_moved(m), to_sq(m));
   }
 }
 
@@ -378,7 +378,7 @@ Move MovePicker::next_move() {
 
       case PH_QRECAPTURES:
           move = (curMove++)->move;
-          if (move_to(move) == recaptureSquare)
+          if (to_sq(move) == recaptureSquare)
               return move;
           break;
 

src/position.cpp

@@ -78,8 +78,8 @@ namespace {
 
 CheckInfo::CheckInfo(const Position& pos) {
 
-  Color them = flip(pos.side_to_move());
-  Square ksq = pos.king_square(them);
+  Color them = ~pos.side_to_move();
+  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 == '/')
-          sq -= Square(16); // Jump back of 2 rows
+      if (isdigit(token))
+          sq += Square(token - '0'); // Advance the given number of files
 
-      else if (isdigit(token))
-          sq += Square(token - '0'); // Skip the given number of files
+      else if (token == '/')
+          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);
-  Square ksq = king_square(FindPinned ? sideToMove : flip(sideToMove));
+  Bitboard pinners = pieces(FindPinned ? ~sideToMove : 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])
-            | (pieces(BISHOP, QUEEN) & BishopPseudoAttacks[ksq]);
+  pinners &=  (pieces(ROOK, QUEEN) & PseudoAttacks[ROOK][ksq])
+            | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq]);
 
   while (pinners)
   {
@@ -420,8 +419,8 @@ bool Position::move_attacks_square(Move m, Square s) const {
   assert(square_is_ok(s));
 
   Bitboard occ, xray;
-  Square from = move_from(m);
-  Square to = move_to(m);
+  Square from = from_sq(m);
+  Square to = to_sq(m);
   Piece piece = piece_on(from);
 
   assert(!square_is_empty(from));
@@ -450,8 +449,8 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
   assert(is_ok(m));
   assert(pinned == pinned_pieces());
 
-  Color us = side_to_move();
-  Square from = move_from(m);
+  Color us = sideToMove;
+  Square from = from_sq(m);
 
   assert(color_of(piece_on(from)) == us);
   assert(piece_on(king_square(us)) == make_piece(us, KING));
@@ -461,8 +460,8 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
   // the move is made.
   if (is_enpassant(m))
   {
-      Color them = flip(us);
-      Square to = move_to(m);
+      Color them = ~us;
+      Square to = to_sq(m);
       Square capsq = to + pawn_push(them);
       Square ksq = king_square(us);
       Bitboard b = occupied_squares();
@@ -484,13 +483,13 @@ 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(move_to(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.
   return   !pinned
         || !bit_is_set(pinned, from)
-        ||  squares_aligned(from, move_to(m), king_square(us));
+        ||  squares_aligned(from, to_sq(m), king_square(us));
 }
 
 
@@ -515,9 +514,9 @@ 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);
-  Square from = move_from(m);
-  Square to = move_to(m);
+  Color them = ~sideToMove;
+  Square from = from_sq(m);
+  Square to = to_sq(m);
   Piece pc = piece_on(from);
 
   // Use a slower but simpler function for uncommon cases
@@ -613,7 +612,7 @@ bool Position::is_pseudo_legal(const Move m) const {
       {
           Bitboard b = occupied_squares();
           clear_bit(&b, from);
-          if (attackers_to(move_to(m), b) & pieces(flip(us)))
+          if (attackers_to(to_sq(m), b) & pieces(~us))
               return false;
       }
       else
@@ -626,7 +625,7 @@ bool Position::is_pseudo_legal(const Move m) const {
 
           // Our move must be a blocking evasion or a capture of the checking piece
           target = squares_between(checksq, king_square(us)) | checkers();
-          if (!bit_is_set(target, move_to(m)))
+          if (!bit_is_set(target, to_sq(m)))
               return false;
       }
   }
@@ -641,10 +640,10 @@ 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(move_from(m))) == side_to_move());
+  assert(color_of(piece_moved(m)) == sideToMove);
 
-  Square from = move_from(m);
-  Square to = move_to(m);
+  Square from = from_sq(m);
+  Square to = to_sq(m);
   PieceType pt = type_of(piece_on(from));
 
   // Direct check ?
@@ -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))
@@ -764,10 +763,10 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
       return;
   }
 
-  Color us = side_to_move();
-  Color them = flip(us);
-  Square from = move_from(m);
-  Square to = move_to(m);
+  Color us = sideToMove;
+  Color them = ~us;
+  Square from = from_sq(m);
+  Square to = to_sq(m);
   Piece piece = piece_on(from);
   PieceType pt = type_of(piece);
   PieceType capture = is_enpassant(m) ? PAWN : type_of(piece_on(to));
@@ -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))
   {
@@ -980,10 +979,10 @@ void Position::undo_move(Move m) {
       return;
   }
 
-  Color us = side_to_move();
-  Color them = flip(us);
-  Square from = move_from(m);
-  Square to = move_to(m);
+  Color us = sideToMove;
+  Color them = ~us;
+  Square from = from_sq(m);
+  Square to = to_sq(m);
   Piece piece = piece_on(to);
   PieceType pt = type_of(piece);
   PieceType capture = st->capturedType;
@@ -1076,9 +1075,9 @@ void Position::do_castle_move(Move m) {
 
   Square kto, kfrom, rfrom, rto, kAfter, rAfter;
 
-  Color us = side_to_move();
-  Square kBefore = move_from(m);
-  Square rBefore = move_to(m);
+  Color us = sideToMove;
+  Square kBefore = from_sq(m);
+  Square rBefore = to_sq(m);
 
   // Find after-castle squares for king and rook
   if (rBefore > kBefore) // O-O
@@ -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)
   {
@@ -1228,8 +1227,8 @@ int Position::see_sign(Move m) const {
 
   assert(is_ok(m));
 
-  Square from = move_from(m);
-  Square to = move_to(m);
+  Square from = from_sq(m);
+  Square to = to_sq(m);
 
   // Early return if SEE cannot be negative because captured piece value
   // is not less then capturing one. Note that king moves always return
@@ -1256,17 +1255,17 @@ int Position::see(Move m) const {
   if (is_castle(m))
       return 0;
 
-  from = move_from(m);
-  to = move_to(m);
+  from = from_sq(m);
+  to = to_sq(m);
   capturedType = type_of(piece_on(to));
   occ = occupied_squares();
 
   // 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 them = flip(us);
+      Color us = sideToMove;
+      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 {
@@ -428,8 +429,8 @@ inline Value Position::non_pawn_material(Color c) const {
 
 inline bool Position::is_passed_pawn_push(Move m) const {
 
-  return   board[move_from(m)] == make_piece(sideToMove, PAWN)
-        && pawn_is_passed(sideToMove, move_to(m));
+  return   board[from_sq(m)] == make_piece(sideToMove, PAWN)
+        && pawn_is_passed(sideToMove, to_sq(m));
 }
 
 inline int Position::startpos_ply_counter() const {
@@ -454,14 +455,14 @@ inline bool Position::is_chess960() const {
 inline bool Position::is_capture_or_promotion(Move m) const {
 
   assert(is_ok(m));
-  return is_special(m) ? !is_castle(m) : !square_is_empty(move_to(m));
+  return is_special(m) ? !is_castle(m) : !square_is_empty(to_sq(m));
 }
 
 inline bool Position::is_capture(Move m) const {
 
   // Note that castle is coded as "king captures the rook"
   assert(is_ok(m));
-  return (!square_is_empty(move_to(m)) && !is_castle(m)) || is_enpassant(m);
+  return (!square_is_empty(to_sq(m)) && !is_castle(m)) || is_enpassant(m);
 }
 
 inline PieceType Position::captured_piece_type() 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]; }
@@ -135,14 +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
-  // better than the second best move.
+  // Easy move margin. An easy move candidate must be at least this much better
+  // 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;
@@ -151,8 +123,6 @@ namespace {
   History H;
 
 
-  /// Local functions
-
   template <NodeType NT>
   Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
 
@@ -197,19 +167,19 @@ 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(move_from(m))) == PAWN)
+    if (type_of(pos.piece_moved(m)) == PAWN)
     {
         Color c = pos.side_to_move();
-        if (   relative_rank(c, move_to(m)) == RANK_7
-            || pos.pawn_is_passed(c, move_to(m)))
+        if (   relative_rank(c, to_sq(m)) == RANK_7
+            || pos.pawn_is_passed(c, to_sq(m)))
             return true;
     }
 
     // Test for a capture that triggers a pawn endgame
     if (   captureOrPromotion
-        && type_of(pos.piece_on(move_to(m))) != PAWN
+        && type_of(pos.piece_on(to_sq(m))) != PAWN
         && (  pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
-            - PieceValueMidgame[pos.piece_on(move_to(m))] == VALUE_ZERO)
+            - PieceValueMidgame[pos.piece_on(to_sq(m))] == VALUE_ZERO)
         && !is_special(m))
         return true;
 
@@ -279,34 +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
-  // 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"])
+  if (RootMoves.empty())
   {
-      if (book.name() != (string)Options["Book File"])
-          book.open(Options["Book File"]);
+      cout << "info depth 0 score "
+           << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW) << endl;
 
-      Move bookMove = book.probe(pos, Options["Best Book Move"]);
-
-      if (   bookMove != MOVE_NONE
-          && count(RootMoves.begin(), RootMoves.end(), bookMove))
-      {
-          std::swap(RootMoves[0], *find(RootMoves.begin(), RootMoves.end(), bookMove));
-          goto finish;
+      RootMoves.push_back(MOVE_NONE);
+      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
@@ -348,8 +313,8 @@ void Search::think() {
 
   // Set best timer interval to avoid lagging under time pressure. Timer is
   // used to check for remaining available thinking time.
-  if (TimeMgr.available_time())
-      Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 8, 20)));
+  if (Limits.use_time_management())
+      Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution)));
   else
       Threads.set_timer(100);
 
@@ -375,11 +340,11 @@ void Search::think() {
       pos.undo_move(RootMoves[0].pv[0]);
   }
 
-finish:
+finalize:
 
-  // When we reach max depth we arrive here even without a StopRequest, but if
-  // we are pondering or in infinite search, we shouldn't print the best move
-  // before we are told to do so.
+  // When we reach max depth we arrive here even without Signals.stop is raised,
+  // but if we are pondering or in infinite search, we shouldn't print the best
+  // move before we are told to do so.
   if (!Signals.stop && (Limits.ponder || Limits.infinite))
       Threads.wait_for_stop_or_ponderhit();
 
@@ -408,16 +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))
     {
@@ -518,7 +473,7 @@ namespace {
             bestMoveNeverChanged = false;
 
         // Do we have time for the next iteration? Can we stop searching now?
-        if (!Signals.stop && !Signals.stopOnPonderhit && Limits.useTimeManagement())
+        if (!Signals.stop && !Signals.stopOnPonderhit && Limits.use_time_management())
         {
             bool stop = false; // Local variable, not the volatile Signals.stop
 
@@ -533,15 +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;
 
@@ -703,10 +658,10 @@ 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 = move_to(move);
+        Square to = to_sq(move);
         H.update_gain(pos.piece_on(to), to, -(ss-1)->eval - ss->eval);
     }
 
@@ -870,7 +825,8 @@ split_point_start: // At split points actual search starts from here
     // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs
     while (   bestValue < beta
            && (move = mp.next_move()) != MOVE_NONE
-           && !thread.cutoff_occurred())
+           && !thread.cutoff_occurred()
+           && !Signals.stop)
     {
       assert(is_ok(move));
 
@@ -971,7 +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(move_from(move)), move_to(move));
+                         + H.gain(pos.piece_moved(move), to_sq(move));
 
           if (futilityValue < beta)
           {
@@ -1155,13 +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(move_from(move)), move_to(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(move_from(m)), move_to(m), -bonus);
+                H.add(pos.piece_moved(m), to_sq(m), -bonus);
             }
         }
     }
@@ -1267,7 +1223,7 @@ split_point_start: // At split points actual search starts from here
     // to search the moves. Because the depth is <= 0 here, only captures,
     // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
     // be generated.
-    MovePicker mp(pos, ttMove, depth, H, move_to((ss-1)->currentMove));
+    MovePicker mp(pos, ttMove, depth, H, to_sq((ss-1)->currentMove));
     CheckInfo ci(pos);
 
     // Loop through the moves until no moves remain or a beta cutoff occurs
@@ -1288,7 +1244,7 @@ split_point_start: // At split points actual search starts from here
           && !pos.is_passed_pawn_push(move))
       {
           futilityValue =  futilityBase
-                         + PieceValueEndgame[pos.piece_on(move_to(move))]
+                         + PieceValueEndgame[pos.piece_on(to_sq(move))]
                          + (is_enpassant(move) ? PawnValueEndgame : VALUE_ZERO);
 
           if (futilityValue < beta)
@@ -1392,9 +1348,9 @@ split_point_start: // At split points actual search starts from here
     Color them;
     Value futilityValue, bv = *bestValue;
 
-    from = move_from(move);
-    to = move_to(move);
-    them = flip(pos.side_to_move());
+    from = from_sq(move);
+    to = to_sq(move);
+    them = ~pos.side_to_move();
     ksq = pos.king_square(them);
     kingAtt = pos.attacks_from<KING>(ksq);
     pc = pos.piece_on(from);
@@ -1453,14 +1409,14 @@ split_point_start: // At split points actual search starts from here
     assert(is_ok(m2));
 
     // Case 1: The moving piece is the same in both moves
-    f2 = move_from(m2);
-    t1 = move_to(m1);
+    f2 = from_sq(m2);
+    t1 = to_sq(m1);
     if (f2 == t1)
         return true;
 
     // Case 2: The destination square for m2 was vacated by m1
-    t2 = move_to(m2);
-    f1 = move_from(m1);
+    t2 = to_sq(m2);
+    f1 = from_sq(m1);
     if (t2 == f1)
         return true;
 
@@ -1533,10 +1489,10 @@ split_point_start: // At split points actual search starts from here
 
     Square mfrom, mto, tfrom, tto;
 
-    mfrom = move_from(m);
-    mto = move_to(m);
-    tfrom = move_from(threat);
-    tto = move_to(threat);
+    mfrom = from_sq(m);
+    mto = to_sq(m);
+    tfrom = from_sq(threat);
+    tto = to_sq(threat);
 
     // Case 1: Don't prune moves which move the threatened piece
     if (mfrom == tto)
@@ -1802,11 +1758,13 @@ 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.
+
+/// 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) {
 
@@ -1838,9 +1796,9 @@ split_point_start: // At split points actual search starts from here
 }
 
 
-  // insert_pv_in_tt() is called at the end of a search iteration, and 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.
+/// RootMove::insert_pv_in_tt() is called at the end of a search iteration, and
+/// 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.
 
 void RootMove::insert_pv_in_tt(Position& pos) {
 
@@ -1869,8 +1827,6 @@ split_point_start: // At split points actual search starts from here
   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.
 /// The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint object
@@ -1962,11 +1918,11 @@ void Thread::idle_loop(SplitPoint* sp) {
 }
 
 
-/// do_timer_event() is called by the timer thread when the timer triggers. It
-/// is used to print debug info and, more important, to detect when we are out of
+/// check_time() is called by the timer thread when the timer triggers. It is
+/// used to print debug info and, more important, to detect when we are out of
 /// available time and so stop the search.
 
-void do_timer_event() {
+void check_time() {
 
   static int lastInfoTime;
   int e = elapsed_time();
@@ -1984,10 +1940,10 @@ void do_timer_event() {
                          && !Signals.failedLowAtRoot
                          &&  e > TimeMgr.available_time();
 
-  bool noMoreTime =   e > TimeMgr.maximum_time()
+  bool noMoreTime =   e > TimeMgr.maximum_time() - 2 * TimerResolution
                    || stillAtFirstMove;
 
-  if (   (Limits.useTimeManagement() && noMoreTime)
+  if (   (Limits.use_time_management() && noMoreTime)
       || (Limits.maxTime && e >= Limits.maxTime)
          /* missing nodes limit */ ) // FIXME
       Signals.stop = true;

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.
@@ -55,7 +78,7 @@ struct Stack {
 struct LimitsType {
 
   LimitsType() { memset(this, 0, sizeof(LimitsType)); }
-  bool useTimeManagement() const { return !(maxTime | maxDepth | maxNodes | infinite); }
+  bool use_time_management() const { return !(maxTime | maxDepth | maxNodes | infinite); }
 
   int time, increment, movesToGo, maxTime, maxDepth, maxNodes, infinite, ponder;
 };
@@ -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"
@@ -172,7 +173,7 @@ void ThreadsManager::init() {
   for (int i = 0; i <= MAX_THREADS; i++)
   {
       threads[i].is_searching = false;
-      threads[i].do_sleep = true;
+      threads[i].do_sleep = (i != 0); // Avoid a race with start_thinking()
       threads[i].threadID = i;
 
 #if defined(_MSC_VER)
@@ -202,7 +203,7 @@ void ThreadsManager::exit() {
 
       // Wait for thread termination
 #if defined(_MSC_VER)
-      WaitForSingleObject(threads[i].handle, 0);
+      WaitForSingleObject(threads[i].handle, INFINITE);
       CloseHandle(threads[i].handle);
 #else
       pthread_join(threads[i].handle, NULL);
@@ -367,7 +368,7 @@ template Value ThreadsManager::split<true>(Position&, Stack*, Value, Value, Valu
 
 // Thread::timer_loop() is where the timer thread waits maxPly milliseconds and
 // then calls do_timer_event(). If maxPly is 0 thread sleeps until is woken up.
-extern void do_timer_event();
+extern void check_time();
 
 void Thread::timer_loop() {
 
@@ -376,7 +377,7 @@ void Thread::timer_loop() {
       lock_grab(&sleepLock);
       timed_wait(&sleepCond, &sleepLock, maxPly ? maxPly : INT_MAX);
       lock_release(&sleepLock);
-      do_timer_event();
+      check_time();
   }
 }
 
@@ -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 +444,23 @@ 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);
 
   lock_release(&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);
 }
@@ -432,11 +427,11 @@ inline Square pawn_push(Color c) {
   return c == WHITE ? DELTA_N : DELTA_S;
 }
 
-inline Square move_from(Move m) {
+inline Square from_sq(Move m) {
   return Square((m >> 6) & 0x3F);
 }
 
-inline Square move_to(Move m) {
+inline Square to_sq(Move m) {
   return Square(m & 0x3F);
 }
 
@@ -464,20 +459,20 @@ inline Move make_move(Square from, Square to) {
   return Move(to | (from << 6));
 }
 
-inline Move make_promotion_move(Square from, Square to, PieceType promotion) {
-  return Move(to | (from << 6) | (1 << 14) | ((promotion - 2) << 12)) ;
+inline Move make_promotion(Square from, Square to, PieceType pt) {
+  return Move(to | (from << 6) | (1 << 14) | ((pt - 2) << 12)) ;
 }
 
-inline Move make_enpassant_move(Square from, Square to) {
+inline Move make_enpassant(Square from, Square to) {
   return Move(to | (from << 6) | (2 << 14));
 }
 
-inline Move make_castle_move(Square from, Square to) {
+inline Move make_castle(Square from, Square to) {
   return Move(to | (from << 6) | (3 << 14));
 }
 
 inline bool is_ok(Move m) {
-  return move_from(m) != move_to(m); // Catches also MOVE_NULL and MOVE_NONE
+  return from_sq(m) != to_sq(m); // Catches also MOVE_NULL and MOVE_NONE
 }
 
 #include <string>

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()];