Fix a possible 'Division by zero'

[stockfish] / src / book.cpp

diff --git a/src/book.cpp b/src/book.cpp
index 1baafbbaabb618f87c2b425a09f3a844fcf3f182..fbb1984cf5cba6ca183465f7b58b5d4bbeaedb0a 100644 (file)
--- a/src/book.cpp
+++ b/src/book.cpp
@@ -315,7 +315,7 @@ namespace {
   uint64_t book_key(const Position& pos) {
 
     uint64_t key = 0;
-    Bitboard b = pos.occupied_squares();
+    Bitboard b = pos.pieces();
 
     while (b)
     {
@@ -323,8 +323,7 @@ namespace {
         key ^= ZobPiece[PieceOffset[pos.piece_on(s)] + s];
     }
 
-    b =  (pos.can_castle(WHITE_OO) << 0) | (pos.can_castle(WHITE_OOO) << 1)
-       | (pos.can_castle(BLACK_OO) << 2) | (pos.can_castle(BLACK_OOO) << 3);
+    b = pos.can_castle(ALL_CASTLES);
 
     while (b)
         key ^= ZobCastle[pop_1st_bit(&b)];
@@ -421,7 +420,7 @@ Move Book::probe(const Position& pos, const string& fName, bool pickBest) {
       // Choose book move according to its score. If a move has a very
       // high score it has higher probability to be choosen than a move
       // with lower score. Note that first entry is always chosen.
-      if (   (RKiss.rand<unsigned>() % sum < e.count)
+      if (   (sum && RKiss.rand<unsigned>() % sum < e.count)
           || (pickBest && e.count == best))
           move = Move(e.move);
   }