From: Marco Costalba <mcostalba@gmail.com>
Date: Mon, 9 Apr 2012 09:34:17 +0000 (+0100)
Subject: Move Tempo to evaluation
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=e72b93e44fb95af6b3669e23a8fcd7702ea09ec1

Move Tempo to evaluation

Apart from the semplification it is now more clear that
the actual Tempo added was half of the indicated score.
This is becuase at start compute_psq_score() added half
Tempo unit and in do_move() white/black were respectively
adding/subtracting one Tempo unit.

Now we have directly halved Tempo constant and everything
is more clear.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 849185b6..d090f404 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -150,6 +150,9 @@ namespace {
 
   #undef S
 
+  // Bonus for having the side to move (modified by Joona Kiiski)
+  const Score Tempo = make_score(24, 11);
+
   // Rooks and queens on the 7th rank (modified by Joona Kiiski)
   const Score RookOn7thBonus  = make_score(47, 98);
   const Score QueenOn7thBonus = make_score(27, 54);
@@ -362,14 +365,15 @@ Value do_evaluate(const Position& pos, Value& margin) {
   Value margins[2];
   Score score, mobilityWhite, mobilityBlack;
 
-  // Initialize score by reading the incrementally updated scores included
-  // in the position object (material + piece square tables).
-  score = pos.psq_score();
-
   // margins[] store the uncertainty estimation of position's evaluation
   // that typically is used by the search for pruning decisions.
   margins[WHITE] = margins[BLACK] = VALUE_ZERO;
 
+  // Initialize score by reading the incrementally updated scores included
+  // in the position object (material + piece square tables) and adding
+  // Tempo bonus. Score is computed from the point of view of white.
+  score = pos.psq_score() + (pos.side_to_move() == WHITE ? Tempo : -Tempo);
+
   // Probe the material hash table
   ei.mi = pos.this_thread()->materialTable.probe(pos);
   score += ei.mi->material_value();
diff --git a/src/position.cpp b/src/position.cpp
index 9af42558..e89477ea 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -62,15 +62,8 @@ const Value PieceValueEndgame[17] = {
   RookValueEndgame, QueenValueEndgame
 };
 
-
-namespace {
-
-  // Bonus for having the side to move (modified by Joona Kiiski)
-  const Score Tempo = make_score(48, 22);
-
-  // To convert a Piece to and from a FEN char
-  const string PieceToChar(" PNBRQK  pnbrqk  .");
-}
+// To convert a Piece to and from a FEN char
+static const string PieceToChar(" PNBRQK  pnbrqk  .");
 
 
 /// CheckInfo c'tor
@@ -934,9 +927,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
       }
   }
 
-  // Finish
   sideToMove = ~sideToMove;
-  st->psqScore += (sideToMove == WHITE ?  Tempo : -Tempo);
 
   assert(pos_is_ok());
 }
@@ -1127,9 +1118,7 @@ void Position::do_castle_move(Move m) {
       // Update checkers BB
       st->checkersBB = attackers_to(king_square(~us)) & pieces(us);
 
-      // Finish
       sideToMove = ~sideToMove;
-      st->psqScore += (sideToMove == WHITE ?  Tempo : -Tempo);
   }
   else
       // Undo: point our state pointer back to the previous state
@@ -1172,7 +1161,6 @@ void Position::do_null_move(StateInfo& backupSt) {
       st->epSquare = SQ_NONE;
       st->rule50++;
       st->pliesFromNull = 0;
-      st->psqScore += (sideToMove == WHITE ?  Tempo : -Tempo);
   }
 
   assert(pos_is_ok());
@@ -1406,18 +1394,15 @@ Key Position::compute_material_key() const {
 /// updated by do_move and undo_move when the program is running in debug mode.
 Score Position::compute_psq_score() const {
 
-  Bitboard b;
   Score result = SCORE_ZERO;
+  Bitboard b = pieces();
 
-  for (Color c = WHITE; c <= BLACK; c++)
-      for (PieceType pt = PAWN; pt <= KING; pt++)
-      {
-          b = pieces(pt, c);
-          while (b)
-              result += pieceSquareTable[make_piece(c, pt)][pop_1st_bit(&b)];
-      }
+  while (b)
+  {
+      Square s = pop_1st_bit(&b);
+      result += pieceSquareTable[piece_on(s)][s];
+  }
 
-  result += (sideToMove == WHITE ? Tempo / 2 : -Tempo / 2);
   return result;
 }