From: Marco Costalba <mcostalba@gmail.com>
Date: Sat, 16 Feb 2013 11:42:22 +0000 (+0100)
Subject: Account for gamePly after each move
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=76caef8ba1fb4ca0520a8e2b42815d626484e93c;hp=5a156df719790ddd882a928ddf721f8ba81587b1

Account for gamePly after each move

Rename startPosPly to gamePly and increment/decrement
the variable after each do/undo move. This adds a little
overhead in do_move() but we will need to have the
game ply during the search for the next patches now
under test.

Currently we don't increment gamePly in do_null_move()
becuase it is not needed at the moment. Could change
in the future.

As a nice side effect we can now remove an hack in
startpos_ply_counter().

No functional change.
---

diff --git a/src/position.cpp b/src/position.cpp
index ad0a621d..a51383f0 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -278,11 +278,11 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) {
   }
 
   // 5-6. Halfmove clock and fullmove number
-  ss >> std::skipws >> st->rule50 >> startPosPly;
+  ss >> std::skipws >> st->rule50 >> gamePly;
 
   // Convert from fullmove starting from 1 to ply starting from 0,
   // handle also common incorrect FEN with fullmove = 0.
-  startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
+  gamePly = std::max(2 * (gamePly - 1), 0) + int(sideToMove == BLACK);
 
   st->key = compute_key();
   st->pawnKey = compute_pawn_key();
@@ -373,7 +373,7 @@ const string Position::fen() const {
       ss << '-';
 
   ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
-      << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
+      << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2;
 
   return ss.str();
 }
@@ -735,8 +735,9 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
   // Update side to move
   k ^= Zobrist::side;
 
-  // Increment the 50 moves rule draw counter. Resetting it to zero in the
-  // case of a capture or a pawn move is taken care of later.
+  // Increment ply counters.In particular rule50 will be later reset it to zero
+  // in case of a capture or a pawn move.
+  gamePly++;
   st->rule50++;
   st->pliesFromNull++;
 
@@ -1054,6 +1055,7 @@ void Position::undo_move(Move m) {
 
   // Finally point our state pointer back to the previous state
   st = st->previous;
+  gamePly--;
 
   assert(pos_is_ok());
 }
@@ -1417,7 +1419,7 @@ void Position::flip() {
   thisThread = pos.this_thread();
   nodes = pos.nodes_searched();
   chess960 = pos.is_chess960();
-  startPosPly = pos.startpos_ply_counter();
+  gamePly = pos.game_ply();
 
   for (Square s = SQ_A1; s <= SQ_H8; s++)
       if (!pos.is_empty(s))
diff --git a/src/position.h b/src/position.h
index 579b5308..fb7eb4b9 100644
--- a/src/position.h
+++ b/src/position.h
@@ -174,7 +174,7 @@ public:
 
   // Other properties of the position
   Color side_to_move() const;
-  int startpos_ply_counter() const;
+  int game_ply() const;
   bool is_chess960() const;
   Thread* this_thread() const;
   int64_t nodes_searched() const;
@@ -218,7 +218,7 @@ private:
   Bitboard castlePath[COLOR_NB][CASTLING_SIDE_NB];
   StateInfo startState;
   int64_t nodes;
-  int startPosPly;
+  int gamePly;
   Color sideToMove;
   Thread* thisThread;
   StateInfo* st;
@@ -376,8 +376,8 @@ inline bool Position::is_passed_pawn_push(Move m) const {
         && pawn_is_passed(sideToMove, to_sq(m));
 }
 
-inline int Position::startpos_ply_counter() const {
-  return startPosPly + st->pliesFromNull; // HACK
+inline int Position::game_ply() const {
+  return gamePly;
 }
 
 inline bool Position::opposite_bishops() const {
diff --git a/src/search.cpp b/src/search.cpp
index 74dc9e29..b9cbb956 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -182,7 +182,7 @@ void Search::think() {
   static PolyglotBook book; // Defined static to initialize the PRNG only once
 
   RootColor = RootPos.side_to_move();
-  TimeMgr.init(Limits, RootPos.startpos_ply_counter(), RootColor);
+  TimeMgr.init(Limits, RootPos.game_ply(), RootColor);
 
   if (RootMoves.empty())
   {