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[stockfish] / src / position.cpp

diff --git a/src/position.cpp b/src/position.cpp
index 120677432b6480f3e35baba5d683768c0e51f123..67dafd8dd78f01f5f17d7178671ccf440631358a 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -102,8 +102,9 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) {
 }
 
 
-// Marcel van Kervinck's cuckoo algorithm for fast detection of "upcoming repetition"
-// situations. Description of the algorithm in the following paper:
+// Implements Marcel van Kervinck's cuckoo algorithm to detect repetition of positions 
+// for 3-fold repetition draws. The algorithm uses two hash tables with Zobrist hashes to 
+// allow fast detection of recurring positions. For details see:
 // http://web.archive.org/web/20201107002606/https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf
 
 // First and second hash functions for indexing the cuckoo tables
@@ -549,7 +550,7 @@ bool Position::legal(Move m) const {
 
 
 /// Position::pseudo_legal() takes a random move and tests whether the move is
-/// pseudo legal. It is used to validate moves from TT that can be corrupted
+/// pseudo-legal. It is used to validate moves from TT that can be corrupted
 /// due to SMP concurrent access or hash position key aliasing.
 
 bool Position::pseudo_legal(const Move m) const {
@@ -565,7 +566,7 @@ bool Position::pseudo_legal(const Move m) const {
       return checkers() ? MoveList<    EVASIONS>(*this).contains(m)
                         : MoveList<NON_EVASIONS>(*this).contains(m);
 
-  // Is not a promotion, so promotion piece must be empty
+  // Is not a promotion, so the promotion piece must be empty
   assert(promotion_type(m) - KNIGHT == NO_PIECE_TYPE);
 
   // If the 'from' square is not occupied by a piece belonging to the side to
@@ -603,7 +604,7 @@ bool Position::pseudo_legal(const Move m) const {
   {
       if (type_of(pc) != KING)
       {
-          // Double check? In this case a king move is required
+          // Double check? In this case, a king move is required
           if (more_than_one(checkers()))
               return false;
 
@@ -611,7 +612,7 @@ bool Position::pseudo_legal(const Move m) const {
           if (!(between_bb(square<KING>(us), lsb(checkers())) & to))
               return false;
       }
-      // In case of king moves under check we have to remove king so as to catch
+      // In case of king moves under check we have to remove the king so as to catch
       // invalid moves like b1a1 when opposite queen is on c1.
       else if (attackers_to(to, pieces() ^ from) & pieces(~us))
           return false;
@@ -1134,7 +1135,7 @@ bool Position::see_ge(Move m, Bitboard& occupied, Value threshold) const {
       }
 
       else // KING
-           // If we "capture" with the king but opponent still has attackers,
+           // If we "capture" with the king but the opponent still has attackers,
            // reverse the result.
           return (attackers & ~pieces(stm)) ? res ^ 1 : res;
   }
@@ -1265,7 +1266,7 @@ void Position::flip() {
 
 
 /// Position::pos_is_ok() performs some consistency checks for the
-/// position object and raises an asserts if something wrong is detected.
+/// position object and raise an assert if something wrong is detected.
 /// This is meant to be helpful when debugging.
 
 bool Position::pos_is_ok() const {