/*
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
void put_threads_to_sleep();
void idle_loop(int threadID, SplitPoint* waitSp);
bool split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue,
- Depth depth, int* moves, MovePicker* mp, int master, bool pvNode);
+ Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode);
private:
- friend void poll(SearchStack ss[], int ply);
+ friend void poll();
int ActiveThreads;
volatile bool AllThreadsShouldExit, AllThreadsShouldSleep;
const Value EasyMoveMargin = Value(0x200);
// Last seconds noise filtering (LSN)
- const bool UseLSNFiltering = true;
+ const bool UseLSNFiltering = false;
const int LSNTime = 4000; // In milliseconds
const Value LSNValue = value_from_centipawns(200);
bool loseOnTime = false;
int MultiPV;
// Time managment variables
- int RootMoveNumber, SearchStartTime, MaxNodes, MaxDepth;
- int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
+ int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime;
+ int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;
- bool AbortSearch, Quit, AspirationFailLow;
-
- // Show current line?
- bool ShowCurrentLine;
+ bool FirstRootMove, AbortSearch, Quit, AspirationFailLow;
// Log file
bool UseLogFile;
/// 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);
int current_search_time();
int nps();
- void poll(SearchStack ss[], int ply);
+ void poll();
void ponderhit();
void wait_for_stop_or_ponderhit();
void init_ss_array(SearchStack ss[]);
// Initialize global search variables
StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false;
+ MaxSearchTime = AbsoluteMaxSearchTime = ExtraSearchTime = 0;
NodesSincePoll = 0;
TM.resetNodeCounters();
SearchStartTime = get_system_time();
MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
- ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
MultiPV = get_option_value_int("MultiPV");
Chess960 = get_option_value_bool("UCI_Chess960");
UseLogFile = get_option_value_bool("Use Search Log");
{
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
// Initialize iteration
Iteration++;
BestMoveChangesByIteration[Iteration] = 0;
- if (Iteration <= 5)
- ExtraSearchTime = 0;
cout << "info depth " << Iteration << endl;
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.
// 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)
// Step 10. Loop through all moves in the root move list
for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
{
- // This is used by time management and starts from 1
- RootMoveNumber = i + 1;
+ // This is used by time management
+ FirstRootMove = (i == 0);
// Save the current node count before the move is searched
nodes = TM.nodes_searched();
if (current_search_time() >= 1000)
cout << "info currmove " << move
- << " currmovenumber " << RootMoveNumber << endl;
+ << " currmovenumber " << i + 1 << endl;
moveIsCheck = pos.move_is_check(move);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
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
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)
// 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;
}
}
} // 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
tte = TT.retrieve(pos.get_key());
}
- // Step 10. Loop through moves
- // Loop through all legal moves until no moves remain or a beta cutoff occurs
-
// Initialize a MovePicker object for the current position
mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move()));
MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
CheckInfo ci(pos);
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
while ( alpha < beta
&& (move = mp.get_next_move()) != MOVE_NONE
&& !TM.thread_should_stop(threadID))
&& !AbortSearch
&& !TM.thread_should_stop(threadID)
&& TM.split(pos, ss, ply, &alpha, beta, &bestValue,
- depth, &moveCount, &mp, threadID, true))
+ depth, mateThreat, &moveCount, &mp, threadID, true))
break;
}
}
// Step 6. Razoring
- if ( !value_is_mate(beta)
+ if ( refinedValue < beta - razor_margin(depth)
+ && ttMove == MOVE_NONE
+ && ss[ply - 1].currentMove != MOVE_NULL
+ && depth < RazorDepth
&& !isCheck
- && depth < RazorDepth
- && refinedValue < beta - razor_margin(depth)
- && ss[ply - 1].currentMove != MOVE_NULL
- && ttMove == MOVE_NONE
+ && !value_is_mate(beta)
&& !pos.has_pawn_on_7th(pos.side_to_move()))
{
Value rbeta = beta - razor_margin(depth);
// Step 7. Static null move pruning
// We're betting that the opponent doesn't have a move that will reduce
- // the score by more than fuility_margin(depth) if we do a null move.
- if ( !isCheck
- && allowNullmove
- && depth < RazorDepth
- && refinedValue - futility_margin(depth, 0) >= beta)
+ // the score by more than futility_margin(depth) if we do a null move.
+ if ( allowNullmove
+ && depth < RazorDepth
+ && !isCheck
+ && !value_is_mate(beta)
+ && ok_to_do_nullmove(pos)
+ && refinedValue >= beta + futility_margin(depth, 0))
return refinedValue - futility_margin(depth, 0);
// Step 8. Null move search with verification search
{
ss[ply].currentMove = MOVE_NULL;
- pos.do_null_move(st);
-
// Null move dynamic reduction based on depth
int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0);
if (refinedValue - beta > PawnValueMidgame)
R++;
+ pos.do_null_move(st);
+
nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
pos.undo_null_move();
if (nullValue >= beta)
{
- if (depth < 6 * OnePly)
- return beta;
+ // Do not return unproven mate scores
+ if (nullValue >= value_mate_in(PLY_MAX))
+ nullValue = beta;
+
+ // Do zugzwang verification search for high depths, don't store in TT
+ // if search was stopped.
+ if ( ( depth < 6 * OnePly
+ || search(pos, ss, beta, depth-5*OnePly, ply, false, threadID) >= beta)
+ && !AbortSearch
+ && !TM.thread_should_stop(threadID))
+ {
+ assert(value_to_tt(nullValue, ply) == nullValue);
- // Do zugzwang verification search
- Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
- if (v >= beta)
- return beta;
+ TT.store(posKey, nullValue, VALUE_TYPE_NS_LO, depth, MOVE_NONE);
+ 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
tte = TT.retrieve(posKey);
}
- // Step 10. Loop through moves
- // Loop through all legal moves until no moves remain or a beta cutoff occurs
-
// Initialize a MovePicker object for the current position
MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], beta);
CheckInfo ci(pos);
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
&& (move = mp.get_next_move()) != MOVE_NONE
&& !TM.thread_should_stop(threadID))
if ( depth >= SingularExtensionDepthAtNonPVNodes
&& tte
&& move == tte->move()
- && !excludedMove // Do not allow recursive single-reply search
+ && !excludedMove // Do not allow recursive singular extension search
&& ext < OnePly
&& is_lower_bound(tte->type())
&& tte->depth() >= depth - 3 * OnePly)
// Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- // Step 14. Reduced search
- // if the move fails high will be re-searched at full depth.
+ // Step 14. Reduced search, if the move fails high
+ // will be re-searched at full depth.
bool doFullDepthSearch = true;
if ( depth >= 3*OnePly
&& !AbortSearch
&& !TM.thread_should_stop(threadID)
&& TM.split(pos, ss, ply, NULL, beta, &bestValue,
- depth, &moveCount, &mp, threadID, false))
+ depth, mateThreat, &moveCount, &mp, threadID, false))
break;
}
// Step 19. Check for mate and stalemate
- // All legal moves have been searched and if there were
+ // All legal moves have been searched and if there are
// no legal moves, it must be mate or stalemate.
- // If one move was excluded return fail low.
+ // If one move was excluded return fail low score.
if (!moveCount)
- return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
+ return excludedMove ? beta - 1 : (isCheck ? value_mated_in(ply) : VALUE_DRAW);
// Step 20. Update tables
// If the search is not aborted, update the transposition table,
alpha = bestValue;
// If we are near beta then try to get a cutoff pushing checks a bit further
- bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8;
+ bool deepChecks = (depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8);
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin[pos.side_to_move()];
- // Loop through the moves until no moves remain or a beta cutoff
- // occurs.
+ // Loop through the moves until no moves remain or a beta cutoff occurs
while ( alpha < beta
&& (move = mp.get_next_move()) != MOVE_NONE)
{
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
- if (!moveCount && pos.is_check()) // Mate!
+ if (!moveCount && isCheck) // Mate!
return value_mated_in(ply);
// Update transposition table
// splitting, we don't have to repeat all this work in sp_search(). We
// also don't need to store anything to the hash table here: This is taken
// care of after we return from the split point.
- // FIXME: We are currently ignoring mateThreat flag here
void sp_search(SplitPoint* sp, int threadID) {
captureOrPromotion = pos.move_is_capture_or_promotion(move);
// Step 11. Decide the new search depth
- ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, false, &dangerous);
+ ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
newDepth = sp->depth - OnePly + ext;
// Update current move
// don't have to repeat all this work in sp_search_pv(). We also don't
// need to store anything to the hash table here: This is taken care of
// after we return from the split point.
- // FIXME: We are ignoring mateThreat flag!
void sp_search_pv(SplitPoint* sp, int threadID) {
captureOrPromotion = pos.move_is_capture_or_promotion(move);
// Step 11. Decide the new search depth
- ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
+ ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
newDepth = sp->depth - OnePly + ext;
// Update current move
NodesSincePoll++;
if (NodesSincePoll >= NodesBetweenPolls)
{
- poll(ss, ply);
+ poll();
NodesSincePoll = 0;
}
}
// looks at the time consumed so far and decides if it's time to abort the
// search.
- void poll(SearchStack ss[], int ply) {
+ void poll() {
static int lastInfoTime;
int t = current_search_time();
cout << "info nodes " << TM.nodes_searched() << " nps " << nps()
<< " time " << t << " hashfull " << TT.full() << endl;
-
- // We only support current line printing in single thread mode
- if (ShowCurrentLine && TM.active_threads() == 1)
- {
- cout << "info currline";
- for (int p = 0; p < ply; p++)
- cout << " " << ss[p].currentMove;
-
- cout << endl;
- }
}
// Should we stop the search?
if (PonderSearch)
return;
- bool stillAtFirstMove = RootMoveNumber == 1
+ bool stillAtFirstMove = FirstRootMove
&& !AspirationFailLow
&& t > MaxSearchTime + ExtraSearchTime;
int t = current_search_time();
PonderSearch = false;
- bool stillAtFirstMove = RootMoveNumber == 1
+ bool stillAtFirstMove = FirstRootMove
&& !AspirationFailLow
&& t > MaxSearchTime + ExtraSearchTime;
bool ThreadsManager::split(const Position& p, SearchStack* sstck, int ply,
Value* alpha, const Value beta, Value* bestValue,
- Depth depth, int* moves, MovePicker* mp, int master, bool pvNode) {
+ Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode) {
assert(p.is_ok());
assert(sstck != NULL);
splitPoint->stopRequest = false;
splitPoint->ply = ply;
splitPoint->depth = depth;
+ splitPoint->mateThreat = mateThreat;
splitPoint->alpha = pvNode ? *alpha : beta - 1;
splitPoint->beta = beta;
splitPoint->pvNode = pvNode;
projects / stockfish / blobdiff