Bench: 24879040

TerjeKir · Jan 3, 2025 · a26356d · a26356d
1 parent 54e8064
commit a26356d
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Showing 3 changed files with 14 additions and 6 deletions.
diff --git a/src/board.c b/src/board.c
@@ -153,7 +153,9 @@ Key KeyAfter(const Position *pos, const Move move) {
     if (capt)
         key ^= PieceKeys[capt][to];
 
-    return key ^ PieceKeys[piece][from] ^ PieceKeys[piece][to];
+    key ^= PieceKeys[piece][from] ^ PieceKeys[piece][to];
+
+    return (capt || PieceTypeOf(piece) == PAWN) ? key : Mr50KeyAfterMove(key, pos->rule50);
 }
 
 // Add a piece piece to a square

diff --git a/src/board.h b/src/board.h
@@ -93,6 +93,10 @@ INLINE bool ValidPiece(const Piece piece) { return (wP <= piece && piece <= wK)
 INLINE bool ValidCapture(const Piece capt) { return (wP <= capt && capt <= wQ) || (bP <= capt && capt <= bQ); }
 INLINE bool ValidPromotion(const Piece promo) { return (wN <= promo && promo <= wQ) || (bN <= promo && promo <= bQ); }
 
+INLINE Key MakeKey(uint64_t seed) { return seed * 6364136223846793005ULL + 1442695040888963407ULL; }
+INLINE Key Mr50Key(const Position *pos) { return pos->rule50 < 14 ? pos->key : pos->key ^ MakeKey((pos->rule50 - 14) / 8); }
+INLINE Key Mr50KeyAfterMove(Key key, int rule50) { return rule50 < 13 ? key : key ^ MakeKey((rule50 - 13) / 8); }
+
 INLINE Color ColorOf(Piece piece) { return piece >> 3;}
 INLINE PieceType PieceTypeOf(Piece piece) { return piece & 7; }
 INLINE Piece MakePiece(Color color, PieceType pt) { return (color << 3) + pt; }

diff --git a/src/search.c b/src/search.c
@@ -126,7 +126,8 @@ static int Quiescence(Thread *thread, Stack *ss, int alpha, int beta) {
 
     // Probe transposition table
     bool ttHit;
-    TTEntry *tte = ProbeTT(pos->key, &ttHit);
+    Key key = Mr50Key(pos);
+    TTEntry *tte = ProbeTT(key, &ttHit);
 
     Move ttMove = ttHit ? tte->move : NOMOVE;
     int ttScore = ttHit ? ScoreFromTT(tte->score, ss->ply) : NOSCORE;
@@ -230,7 +231,7 @@ static int Quiescence(Thread *thread, Stack *ss, int alpha, int beta) {
     if (inCheck && bestScore == -INFINITE)
         return matedIn(ss->ply);
 
-    StoreTTEntry(tte, pos->key, bestMove, ScoreToTT(bestScore, ss->ply), unadjustedEval, 0,
+    StoreTTEntry(tte, key, bestMove, ScoreToTT(bestScore, ss->ply), unadjustedEval, 0,
                  bestScore >= beta ? BOUND_LOWER : BOUND_UPPER);
 
     return bestScore;
@@ -287,7 +288,8 @@ static int AlphaBeta(Thread *thread, Stack *ss, int alpha, int beta, Depth depth
 
     // Probe transposition table
     bool ttHit;
-    TTEntry *tte = ProbeTT(pos->key, &ttHit);
+    Key key = Mr50Key(pos);
+    TTEntry *tte = ProbeTT(key, &ttHit);
 
     Move ttMove = ttHit ? tte->move : NOMOVE;
     int ttScore = ttHit ? ScoreFromTT(tte->score, ss->ply) : NOSCORE;
@@ -321,7 +323,7 @@ static int AlphaBeta(Thread *thread, Stack *ss, int alpha, int beta, Depth depth
 
         // Draw scores are exact, while wins are lower bounds and losses upper bounds (mate scores are better/worse)
         if (bound == BOUND_EXACT || (bound == BOUND_LOWER ? tbScore >= beta : tbScore <= alpha)) {
-            StoreTTEntry(tte, pos->key, NOMOVE, ScoreToTT(tbScore, ss->ply), NOSCORE, MAX_PLY, bound);
+            StoreTTEntry(tte, key, NOMOVE, ScoreToTT(tbScore, ss->ply), NOSCORE, MAX_PLY, bound);
             return tbScore;
         }
 
@@ -635,7 +637,7 @@ static int AlphaBeta(Thread *thread, Stack *ss, int alpha, int beta, Depth depth
 
     // Store in TT
     if (!ss->excluded && (!root || !thread->multiPV))
-        StoreTTEntry(tte, pos->key, bestMove, ScoreToTT(bestScore, ss->ply), unadjustedEval, depth,
+        StoreTTEntry(tte, key, bestMove, ScoreToTT(bestScore, ss->ply), unadjustedEval, depth,
                        bestScore >= beta  ? BOUND_LOWER
                      : pvNode && bestMove ? BOUND_EXACT
                                           : BOUND_UPPER);