Add RULE_50 macro

include/config.h

@@ -97,6 +97,7 @@
 //#define ENDGAME_LEARNING_FORCE
 
 #define THREEFOLD_REPETITION
+#define RULE_50
 
 //#define MESSAGEBOX_ENABLE
 

src/position.cpp

@@ -941,6 +941,7 @@ bool Position::check_if_game_is_over()
         return true;
     }
 
+#ifdef RULE_50
     if (rule.maxStepsLedToDraw > 0 &&
         posKeyHistory.size() > rule.maxStepsLedToDraw) {
         winner = DRAW;
@@ -948,6 +949,7 @@ bool Position::check_if_game_is_over()
         gameOverReason = GameOverReason::drawReasonRule50;
         return true;
     }
+#endif // RULE_50
 
     if (pieceOnBoardCount[BLACK] + pieceOnBoardCount[WHITE] >= EFFECTIVE_SQUARE_NB) {
         if (rule.isBlackLoseButNotDrawWhenBoardFull) {

src/search.cpp

@@ -93,9 +93,12 @@ int Thread::search()
 #endif
 
     if (rootPos->get_phase() == Phase::moving) {
+#ifdef RULE_50
         if (posKeyHistory.size() > rule.maxStepsLedToDraw) {
             return 99;
         }
+#endif // RULE_50
+
 #ifdef THREEFOLD_REPETITION
         if (rootPos->has_game_cycle()) {
             return 3;
@@ -204,12 +207,14 @@ Value search(Position *pos, Sanmill::Stack<Position> &ss, Depth depth, Depth ori
 
     Depth epsilon;
 
+#ifdef RULE_50
     if (pos->rule50_count() > 99) {
         alpha = VALUE_DRAW;
         if (alpha >= beta) {
             return alpha;
         }
     }
+#endif // RULE_50
 
 #ifdef THREEFOLD_REPETITION_TEST
     // Check if we have an upcoming move which draws by repetition, or