X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=176806976bb4234105d25826a973097537984b4a;hp=c5c63c2b3862701ffdf65ba258d0a407b82c2a5c;hb=4d170725ab0ea2d219ff402495a1c541e7f75d6c;hpb=2f6927ac08887ff3b709cfe9228b27a85bdd1d88

diff --git a/src/position.cpp b/src/position.cpp
index c5c63c2b..17680697 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -641,10 +641,10 @@ bool Position::move_is_check(Move m, const CheckInfo& ci) const {
       }
   }
 
-  // En passant capture with check?  We have already handled the case
+  // En passant capture with check ? We have already handled the case
   // of direct checks and ordinary discovered check, the only case we
-  // need to handle is the unusual case of a discovered check through the
-  // captured pawn.
+  // need to handle is the unusual case of a discovered check through
+  // the captured pawn.
   if (move_is_ep(m))
   {
       Square capsq = make_square(square_file(to), square_rank(from));
@@ -703,7 +703,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
   // pointer to point to the new, ready to be updated, state.
   struct ReducedStateInfo {
     Key pawnKey, materialKey;
-    int castleRights, rule50, ply, pliesFromNull;
+    int castleRights, rule50, gamePly, pliesFromNull;
     Square epSquare;
     Score value;
     Value npMaterial[2];
@@ -715,7 +715,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
 
   // Save the current key to the history[] array, in order to be able to
   // detect repetition draws.
-  history[st->ply++] = key;
+  history[st->gamePly++] = key;
 
   // Update side to move
   key ^= zobSideToMove;
@@ -772,7 +772,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
   }
 
   // Prefetch TT access as soon as we know key is updated
-  TT.prefetch(key);
+  prefetch((char*)TT.first_entry(key));
 
   // Move the piece
   Bitboard move_bb = make_move_bb(from, to);
@@ -1243,14 +1243,14 @@ void Position::do_null_move(StateInfo& backupSt) {
 
   // Save the current key to the history[] array, in order to be able to
   // detect repetition draws.
-  history[st->ply++] = st->key;
+  history[st->gamePly++] = st->key;
 
   // Update the necessary information
   if (st->epSquare != SQ_NONE)
       st->key ^= zobEp[st->epSquare];
 
   st->key ^= zobSideToMove;
-  TT.prefetch(st->key);
+  prefetch((char*)TT.first_entry(st->key));
 
   sideToMove = opposite_color(sideToMove);
   st->epSquare = SQ_NONE;
@@ -1278,7 +1278,7 @@ void Position::undo_null_move() {
   // Update the necessary information
   sideToMove = opposite_color(sideToMove);
   st->rule50--;
-  st->ply--;
+  st->gamePly--;
 }
 
 
@@ -1307,11 +1307,11 @@ int Position::see_sign(Move m) const {
   Square from = move_from(m);
   Square to = move_to(m);
 
-  // Early return if SEE cannot be negative because capturing piece value
-  // is not bigger then captured one.
-  if (   midgame_value_of_piece_on(from) <= midgame_value_of_piece_on(to)
-      && type_of_piece_on(from) != KING)
-         return 1;
+  // Early return if SEE cannot be negative because captured piece value
+  // is not less then capturing one. Note that king moves always return
+  // here because king midgame value is set to 0.
+  if (midgame_value_of_piece_on(to) >= midgame_value_of_piece_on(from))
+      return 1;
 
   return see(from, to);
 }
@@ -1481,15 +1481,15 @@ void Position::clear() {
 }
 
 
-/// Position::reset_ply() simply sets ply to 0. It is used from the
+/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the
 /// UCI interface code, whenever a non-reversible move is made in a
 /// 'position fen <fen> moves m1 m2 ...' command.  This makes it possible
 /// for the program to handle games of arbitrary length, as long as the GUI
 /// handles draws by the 50 move rule correctly.
 
-void Position::reset_ply() {
+void Position::reset_game_ply() {
 
-  st->ply = 0;
+  st->gamePly = 0;
 }
 
 
@@ -1666,11 +1666,9 @@ bool Position::is_draw() const {
   if (st->rule50 > 100 || (st->rule50 == 100 && !is_check()))
       return true;
 
-  assert(st->ply >= st->rule50);
-
   // Draw by repetition?
-  for (int i = 4, e = Min(st->rule50, st->pliesFromNull); i <= e; i += 2)
-      if (history[st->ply - i] == st->key)
+  for (int i = 4, e = Min(Min(st->gamePly, st->rule50), st->pliesFromNull); i <= e; i += 2)
+      if (history[st->gamePly - i] == st->key)
           return true;
 
   return false;