Added files via upload

Srcs/bitboard.h

@@ -270,10 +270,6 @@ inline int popcount(Bitboard b) {
 
   return (int)_mm_popcnt_u64(b);
 
-#elif defined(_MSC_VER)
-
-  return (int)__popcnt64(b);
-
 #else // Assumed gcc or compatible compiler
 
   return __builtin_popcountll(b);

Srcs/evaluate.cpp

@@ -189,7 +189,8 @@ namespace {
   const Score Unstoppable        = S( 0, 20);
         Score Hanging            = S(48, 27);
   const Score PawnAttackThreat   = S(38, 22);
-  const Score Checked            = S(20, 20);
+  const Score SafeCheck          = S(20, 20);
+  const Score OtherCheck         = S(10, 10);
 
   // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
   // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
@@ -392,9 +393,10 @@ namespace {
   template<Color Us, bool Trace>
   Score evaluate_king(const Position& pos, const EvalInfo& ei) {
 
-    const Color Them = (Us == WHITE ? BLACK : WHITE);
+    const Color Them = (Us == WHITE ? BLACK   : WHITE);
+	const Square  Up = (Us == WHITE ? DELTA_N : DELTA_S);
 
-    Bitboard undefended, b, b1, b2, safe;
+    Bitboard undefended, b, b1, b2, safe, other;
     int attackUnits;
     const Square ksq = pos.square<KING>(Us);
 
@@ -441,27 +443,42 @@ namespace {
             if (b)attackUnits += QueenContactCheck * popcount(b);
         }
 
-        // Analyse the enemy's safe distance checks for sliders and knights
-        safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
+        // Analyse the safe enemy's checks which are possible on next move...
+        safe  = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
+
+		// ... and some other potential checks, only requiring the square to be
+		// safe from pawn-attacks, and not being occupied by a blocked pawn.
+		other = ~(   ei.attackedBy[Us][PAWN]
+		          | (pos.pieces(Them, PAWN) & shift_bb<Up>(pos.pieces(PAWN))));
 
-        b1 = pos.attacks_from<ROOK  >(ksq) & safe;
-        b2 = pos.attacks_from<BISHOP>(ksq) & safe;
+        b1 = pos.attacks_from<ROOK  >(ksq);
+        b2 = pos.attacks_from<BISHOP>(ksq);
 
         // Enemy queen safe checks
-        if ((b1 | b2) & ei.attackedBy[Them][QUEEN])
-            attackUnits += QueenCheck, score -= Checked;
-
-        // Enemy rooks safe checks
-        if (b1 & ei.attackedBy[Them][ROOK])
-            attackUnits += RookCheck, score -= Checked;
-
-        // Enemy bishops safe checks
-        if (b2 & ei.attackedBy[Them][BISHOP])
-            attackUnits += BishopCheck, score -= Checked;
-
-        // Enemy knights safe checks
-        if (pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe)
-            attackUnits += KnightCheck, score -= Checked;
+        if ((b1 | b2) & ei.attackedBy[Them][QUEEN] & safe)
+            attackUnits += QueenCheck, score -= SafeCheck;
+
+		// Enemy rooks safe and other checks
+		if (b1 & ei.attackedBy[Them][ROOK] & safe)
+			attackUnits += RookCheck, score -= SafeCheck;
+
+		else if (b1 & ei.attackedBy[Them][ROOK] & other)
+			score -= OtherCheck;
+
+		// Enemy bishops safe and other checks
+		if (b2 & ei.attackedBy[Them][BISHOP] & safe)
+			attackUnits += BishopCheck, score -= SafeCheck;
+
+        else if (b2 & ei.attackedBy[Them][BISHOP] & other)
+			score -= OtherCheck;
+
+        // Enemy knights safe and other checks
+		b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT];
+		if (b & safe)
+			attackUnits += KnightCheck, score -= SafeCheck;
+
+        else if (b & other)
+			score -= OtherCheck;
 
         // Finally, extract the king danger score from the KingDanger[]
         // array and subtract the score from the evaluation.

Srcs/misc.cpp

@@ -30,7 +30,7 @@ namespace {
 
 /// Version number. If Version is left empty, then compile date in the format
 /// DD-MM-YY and show in engine_info.
-static const string Version = "Nayeem 5.1";
+static const string Version = "Nayeem 5.2";
 
 /// Our fancy logging facility. The trick here is to replace cin.rdbuf() and
 /// cout.rdbuf() with two Tie objects that tie cin and cout to a file stream. We

Srcs/search.cpp

@@ -1011,13 +1011,12 @@ namespace {
 		  Value fmValue = (fm ? (*fm)[pos.piece_on(to_sq(move))][to_sq(move)] : VALUE_ZERO);
 		  Value fm2Value = (fm2 ? (*fm2)[pos.piece_on(to_sq(move))][to_sq(move)] : VALUE_ZERO);
 
-          // Increase reduction for cut nodes and moves with a bad history
-          if (   (!PvNode && cutNode)
-              || (hValue < VALUE_ZERO && cmhValue <= VALUE_ZERO))
+          // Increase reduction for cut nodes
+		  if (!PvNode && cutNode)
               r += ONE_PLY;
 
           // Decrease/increase reduction for moves with a good/bad history
-          int rHist = (hValue + cmhValue + fmValue + fm2Value) / 20000;
+          int rHist = (hValue + cmhValue + fmValue + fm2Value - 10000) / 20000;
           r = std::max(DEPTH_ZERO, r - rHist * ONE_PLY);
 
           // Decrease reduction for moves that escape a capture. Filter out

Srcs/types.h

@@ -58,13 +58,13 @@
 /// _WIN64             Building on Windows 64 bit
 
 #if defined(_WIN64) && defined(_MSC_VER) // No Makefile used
-#  include <intrin.h> // MSVC popcnt and bsfq instrinsics
+#  include <intrin.h> // Microsoft header for _BitScanForward64()
 #  define IS_64BIT
 #endif
 
 
 #if defined(USE_POPCNT) && (defined(__INTEL_COMPILER) || defined(_MSC_VER))
-#  include <nmmintrin.h> // Intel header for _mm_popcnt_u64() intrinsic
+#  include <nmmintrin.h> // Intel and Microsoft header for _mm_popcnt_u64()
 #endif
 
 #if !defined(NO_PREFETCH) && (defined(__INTEL_COMPILER) || defined(_MSC_VER))