X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=67c98709521ae5d63707a56d39a2f63b2a010d41;hp=45c040f7fba80676459123d71012eee0032b6f17;hb=42de93ac15366d6d20c1b2fbf99b4780e8ac6617;hpb=cc2a249952a93b134e67834b47000e455135e28f

diff --git a/src/search.cpp b/src/search.cpp
index 45c040f7..67c98709 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2009 Marco Costalba
+  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -282,7 +282,7 @@ namespace {
   /// Local functions
 
   Value id_loop(const Position& pos, Move searchMoves[]);
-  Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta);
+  Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr);
   Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
   Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE);
   Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
@@ -373,6 +373,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
 
   // Initialize global search variables
   StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false;
+  MaxSearchTime = AbsoluteMaxSearchTime = ExtraSearchTime = 0;
   NodesSincePoll = 0;
   TM.resetNodeCounters();
   SearchStartTime = get_system_time();
@@ -440,10 +441,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
   {
       TM.set_active_threads(newActiveThreads);
       init_eval(TM.active_threads());
-      // HACK: init_eval() destroys the static castleRightsMask[] array in the
-      // Position class. The below line repairs the damage.
-      Position p(pos.to_fen());
-      assert(pos.is_ok());
   }
 
   // Wake up sleeping threads
@@ -647,8 +644,6 @@ namespace {
         // Initialize iteration
         Iteration++;
         BestMoveChangesByIteration[Iteration] = 0;
-        if (Iteration <= 5)
-            ExtraSearchTime = 0;
 
         cout << "info depth " << Iteration << endl;
 
@@ -665,8 +660,8 @@ namespace {
             beta  = Min(ValueByIteration[Iteration - 1] + AspirationDelta,  VALUE_INFINITE);
         }
 
-        // Search to the current depth, rml is updated and sorted
-        value = root_search(p, ss, rml, alpha, beta);
+        // Search to the current depth, rml is updated and sorted, alpha and beta could change
+        value = root_search(p, ss, rml, &alpha, &beta);
 
         // Write PV to transposition table, in case the relevant entries have
         // been overwritten during the search.
@@ -786,18 +781,21 @@ namespace {
   // scheme, prints some information to the standard output and handles
   // the fail low/high loops.
 
-  Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta) {
+  Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr) {
 
     EvalInfo ei;
     StateInfo st;
+    CheckInfo ci(pos);
     int64_t nodes;
     Move move;
     Depth depth, ext, newDepth;
-    Value value, alpha;
+    Value value, alpha, beta;
     bool isCheck, moveIsCheck, captureOrPromotion, dangerous;
-    int researchCount = 0;
-    CheckInfo ci(pos);
-    alpha = oldAlpha;
+    int researchCountFH, researchCountFL;
+
+    researchCountFH = researchCountFL = 0;
+    alpha = *alphaPtr;
+    beta = *betaPtr;
     isCheck = pos.is_check();
 
     // Step 1. Initialize node and poll (omitted at root, but I can see no good reason for this, FIXME)
@@ -929,8 +927,8 @@ namespace {
                 print_pv_info(pos, ss, alpha, beta, value);
 
                 // Prepare for a research after a fail high, each time with a wider window
-                researchCount++;
-                beta = Min(beta + AspirationDelta * (1 << researchCount), VALUE_INFINITE);
+                *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCountFH), VALUE_INFINITE);
+                researchCountFH++;
 
             } // End of fail high loop
 
@@ -950,6 +948,7 @@ namespace {
             rml.set_move_nodes(i, TM.nodes_searched() - nodes);
 
             assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
+            assert(value < beta);
 
             // Step 17. Check for new best move
             if (value <= alpha && i >= MultiPV)
@@ -975,8 +974,7 @@ namespace {
                     // Print information to the standard output
                     print_pv_info(pos, ss, alpha, beta, value);
 
-                    // Raise alpha to setup proper non-pv search upper bound, note
-                    // that we can end up with alpha >= beta and so get a fail high.
+                    // Raise alpha to setup proper non-pv search upper bound
                     if (value > alpha)
                         alpha = value;
                 }
@@ -1002,22 +1000,21 @@ namespace {
                 }
             } // PV move or new best move
 
-            assert(alpha >= oldAlpha);
+            assert(alpha >= *alphaPtr);
 
-            AspirationFailLow = (alpha == oldAlpha);
+            AspirationFailLow = (alpha == *alphaPtr);
 
             if (AspirationFailLow && StopOnPonderhit)
                 StopOnPonderhit = false;
         }
 
         // Can we exit fail low loop ?
-        if (AbortSearch || alpha > oldAlpha)
+        if (AbortSearch || !AspirationFailLow)
             break;
 
         // Prepare for a research after a fail low, each time with a wider window
-        researchCount++;
-        alpha = Max(alpha - AspirationDelta * (1 << researchCount), -VALUE_INFINITE);
-        oldAlpha = alpha;
+        *alphaPtr = alpha = Max(alpha - AspirationDelta * (1 << researchCountFL), -VALUE_INFINITE);
+        researchCountFL++;
 
     } // Fail low loop
 
@@ -1381,13 +1378,17 @@ namespace {
 
         if (nullValue >= beta)
         {
+            // Do not return unproven mate scores
+            if (nullValue >= value_mate_in(PLY_MAX))
+                nullValue = beta;
+
             if (depth < 6 * OnePly)
-                return beta;
+                return nullValue;
 
             // Do zugzwang verification search
             Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
             if (v >= beta)
-                return beta;
+                return nullValue;
         } else {
             // The null move failed low, which means that we may be faced with
             // some kind of threat. If the previous move was reduced, check if