Fix score_to_uci()

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index b10eec60216db7805cda791065e5a67f011d2440..636ebd8ef6654b4a31f325b752ca5e1d0dceab53 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -410,10 +410,10 @@ namespace {
     bestValue = delta = -VALUE_INFINITE;
     ss->currentMove = MOVE_NULL; // Hack to skip update gains
 
-    // Handle the special case of a mate/stalemate position
+    // Handle the special case of a mated/stalemate position
     if (RootMoves.empty())
     {
-        cout << "info depth 0"
+        cout << "info depth 0 score "
              << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW) << endl;
 
         RootMoves.push_back(MOVE_NONE);
@@ -640,11 +640,16 @@ namespace {
          || ss->ply > PLY_MAX) && !RootNode)
         return VALUE_DRAW;
 
-    // Step 3. Mate distance pruning
+    // Step 3. Mate distance pruning. Even if we mate at the next move our score
+    // would be at best mate_in(ss->ply+1), but if alpha is already bigger because
+    // a shorter mate was found upward in the tree then there is no need to search
+    // further, we will never beat current alpha. Same logic but with reversed signs
+    // applies also in the opposite condition of being mated instead of giving mate,
+    // in this case return a fail-high score.
     if (!RootNode)
     {
-        alpha = std::max(value_mated_in(ss->ply), alpha);
-        beta = std::min(value_mate_in(ss->ply+1), beta);
+        alpha = std::max(mated_in(ss->ply), alpha);
+        beta = std::min(mate_in(ss->ply+1), beta);
         if (alpha >= beta)
             return alpha;
     }
@@ -701,7 +706,7 @@ namespace {
     if (   (move = (ss-1)->currentMove) != MOVE_NULL
         && (ss-1)->eval != VALUE_NONE
         && ss->eval != VALUE_NONE
-        && pos.captured_piece_type() == PIECE_TYPE_NONE
+        && pos.captured_piece_type() == NO_PIECE_TYPE
         && !is_special(move))
     {
         Square to = move_to(move);
@@ -1122,7 +1127,7 @@ split_point_start: // At split points actual search starts from here
     // harmless because return value is discarded anyhow in the parent nodes.
     // If we are in a singular extension search then return a fail low score.
     if (!moveCount)
-        return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW;
+        return excludedMove ? oldAlpha : inCheck ? mated_in(ss->ply) : VALUE_DRAW;
 
     // If we have pruned all the moves without searching return a fail-low score
     if (bestValue == -VALUE_INFINITE)
@@ -1365,7 +1370,7 @@ split_point_start: // At split points actual search starts from here
     // All legal moves have been searched. A special case: If we're in check
     // and no legal moves were found, it is checkmate.
     if (inCheck && bestValue == -VALUE_INFINITE)
-        return value_mated_in(ss->ply);
+        return mated_in(ss->ply); // Plies to mate from the root
 
     // Update transposition table
     move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
@@ -1490,8 +1495,8 @@ split_point_start: // At split points actual search starts from here
 
 
   // value_to_tt() adjusts a mate score from "plies to mate from the root" to
-  // "plies to mate from the current ply". Non-mate scores are unchanged. The
-  // function is called before storing a value to the transposition table.
+  // "plies to mate from the current position". Non-mate scores are unchanged.
+  // The function is called before storing a value to the transposition table.
 
   Value value_to_tt(Value v, int ply) {
 
@@ -1505,8 +1510,9 @@ split_point_start: // At split points actual search starts from here
   }
 
 
-  // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score from
-  // the transposition table to a mate score corrected for the current ply.
+  // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score
+  // from the transposition table (where refers to the plies to mate/be mated
+  // from current position) to "plies to mate/be mated from the root".
 
   Value value_from_tt(Value v, int ply) {
 
@@ -1618,10 +1624,10 @@ split_point_start: // At split points actual search starts from here
 
     std::stringstream s;
 
-    if (abs(v) < VALUE_MATE - PLY_MAX * ONE_PLY)
-        s << " score cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to centipawns
+    if (abs(v) < VALUE_MATE_IN_PLY_MAX)
+        s << "cp " << v * 100 / int(PawnValueMidgame);
     else
-        s << " score mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
+        s << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
 
     s << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");
 
@@ -1658,7 +1664,7 @@ split_point_start: // At split points actual search starts from here
 
         cout << "info depth " << d
              << " seldepth " << selDepth
-             << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v))
+             << " score " << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v))
              << " nodes " << pos.nodes_searched()
              << " nps " << (t > 0 ? pos.nodes_searched() * 1000 / t : 0)
              << " time " << t