Tablebases root ranking

[stockfish] / src / position.cpp

diff --git a/src/position.cpp b/src/position.cpp
index 9cec2c14ff9646882a06f3abd02290248196d8f2..0be309ee60cac3d0ea78bcec0ad6c38237e7768b 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -52,8 +52,8 @@ namespace {
 
 const string PieceToChar(" PNBRQK  pnbrqk");
 
-const Piece Pieces[] = { W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING,
-                         B_PAWN, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING };
+constexpr Piece Pieces[] = { W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING,
+                             B_PAWN, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING };
 
 // min_attacker() is a helper function used by see_ge() to locate the least
 // valuable attacker for the side to move, remove the attacker we just found
@@ -1105,6 +1105,35 @@ bool Position::is_draw(int ply) const {
 }
 
 
+// Position::has_repeated() tests whether there has been at least one repetition
+// of positions since the last capture or pawn move.
+
+bool Position::has_repeated() const {
+
+    StateInfo* stc = st;
+    while (true)
+    {
+        int i = 4, e = std::min(stc->rule50, stc->pliesFromNull);
+
+        if (e < i)
+            return false;
+
+        StateInfo* stp = st->previous->previous;
+
+        do {
+            stp = stp->previous->previous;
+
+            if (stp->key == stc->key)
+                return true;
+
+            i += 2;
+        } while (i <= e);
+
+        stc = stc->previous;
+    }
+}
+
+
 /// Position::flip() flips position with the white and black sides reversed. This
 /// is only useful for debugging e.g. for finding evaluation symmetry bugs.
 
@@ -1146,7 +1175,7 @@ void Position::flip() {
 
 bool Position::pos_is_ok() const {
 
-  const bool Fast = true; // Quick (default) or full check?
+  constexpr bool Fast = true; // Quick (default) or full check?
 
   if (   (sideToMove != WHITE && sideToMove != BLACK)
       || piece_on(square<KING>(WHITE)) != W_KING