LimitsType Limits;
std::vector<RootMove> RootMoves;
Position RootPosition;
+ Color RootColor;
Time::point SearchTime;
StateStackPtr SetupStates;
}
int BestMoveChanges;
int SkillLevel;
bool SkillLevelEnabled, Chess960;
+ Value DrawValue[2];
History H;
template <NodeType NT>
bool connected_moves(const Position& pos, Move m1, Move m2);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
- bool can_return_tt(const TTEntry* tte, Depth depth, Value ttValue, Value beta);
bool connected_threat(const Position& pos, Move m, Move threat);
Value refine_eval(const TTEntry* tte, Value ttValue, Value defaultEval);
Move do_skill_level();
string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
- // is_dangerous() checks whether a move belongs to some classes of known
- // 'dangerous' moves so that we avoid to prune it.
- FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) {
-
- // Castle move?
- if (type_of(m) == CASTLE)
- return true;
-
- // Passed pawn move?
- if ( type_of(pos.piece_moved(m)) == PAWN
- && pos.pawn_is_passed(pos.side_to_move(), to_sq(m)))
- return true;
-
- // Entering a pawn endgame?
- if ( captureOrPromotion
- && type_of(pos.piece_on(to_sq(m))) != PAWN
- && type_of(m) == NORMAL
- && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- - PieceValue[Mg][pos.piece_on(to_sq(m))] == VALUE_ZERO))
- return true;
-
- return false;
- }
-
} // namespace
// Init futility move count array
for (d = 0; d < 32; d++)
- FutilityMoveCounts[d] = int(3.001 + 0.25 * pow(d, 2.0));
+ FutilityMoveCounts[d] = int(3.001 + 0.25 * pow(double(d), 2.0));
}
Position& pos = RootPosition;
Chess960 = pos.is_chess960();
- Eval::RootColor = pos.side_to_move();
- Eval::ValueDraw[ Eval::RootColor] = VALUE_DRAW - Eval::ContemptFactor;
- Eval::ValueDraw[~Eval::RootColor] = VALUE_DRAW + Eval::ContemptFactor;
+ RootColor = pos.side_to_move();
TimeMgr.init(Limits, pos.startpos_ply_counter(), pos.side_to_move());
TT.new_search();
H.clear();
goto finalize;
}
+ if (Options["Contempt Factor"] && !Options["UCI_AnalyseMode"])
+ {
+ int cf = Options["Contempt Factor"] * PawnValueMg / 100; // In centipawns
+ cf = cf * MaterialTable::game_phase(pos) / PHASE_MIDGAME; // Scale down with phase
+ DrawValue[ RootColor] = VALUE_DRAW - Value(cf);
+ DrawValue[~RootColor] = VALUE_DRAW + Value(cf);
+ }
+ else
+ DrawValue[WHITE] = DrawValue[BLACK] = VALUE_DRAW;
+
if (Options["OwnBook"] && !Limits.infinite)
{
Move bookMove = book.probe(pos, Options["Book File"], Options["Best Book Move"]);
Depth ext, newDepth;
Value bestValue, value, ttValue;
Value refinedValue, nullValue, futilityValue;
- bool pvMove, inCheck, singularExtensionNode, givesCheck;
+ bool inCheck, givesCheck, pvMove, singularExtensionNode;
bool captureOrPromotion, dangerous, doFullDepthSearch;
int moveCount, playedMoveCount;
{
// Step 2. Check for aborted search and immediate draw
if (Signals.stop || pos.is_draw<false>() || ss->ply > MAX_PLY)
- return Eval::ValueDraw[pos.side_to_move()];
+ return DrawValue[pos.side_to_move()];
// 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 fail high/low. Biggest advantage at probing at PV nodes is to have a
// smooth experience in analysis mode. We don't probe at Root nodes otherwise
// we should also update RootMoveList to avoid bogus output.
- if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == BOUND_EXACT
- : can_return_tt(tte, depth, ttValue, beta)))
+ if ( !RootNode
+ && tte && tte->depth() >= depth
+ && ( PvNode ? tte->type() == BOUND_EXACT
+ : ttValue >= beta ? (tte->type() & BOUND_LOWER)
+ : (tte->type() & BOUND_UPPER)))
{
+ assert(ttValue != VALUE_NONE); // Due to depth > DEPTH_NONE
+
TT.refresh(tte);
ss->currentMove = ttMove; // Can be MOVE_NONE
// Step 5. Evaluate the position statically and update parent's gain statistics
if (inCheck)
ss->eval = ss->evalMargin = refinedValue = VALUE_NONE;
+
else if (tte)
{
assert(tte->static_value() != VALUE_NONE);
else
{
refinedValue = ss->eval = evaluate(pos, ss->evalMargin);
- TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin);
+ TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE,
+ ss->eval, ss->evalMargin);
}
// Update gain for the parent non-capture move given the static position
<< " currmovenumber " << moveCount + PVIdx << sync_endl;
}
+ ext = DEPTH_ZERO;
captureOrPromotion = pos.is_capture_or_promotion(move);
givesCheck = pos.move_gives_check(move, ci);
- dangerous = givesCheck || is_dangerous(pos, move, captureOrPromotion);
- ext = DEPTH_ZERO;
+ dangerous = givesCheck
+ || pos.is_passed_pawn_push(move)
+ || type_of(move) == CASTLE
+ || ( captureOrPromotion // Entering a pawn endgame?
+ && type_of(pos.piece_on(to_sq(move))) != PAWN
+ && type_of(move) == NORMAL
+ && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
+ - PieceValue[Mg][pos.piece_on(to_sq(move))] == VALUE_ZERO));
// Step 12. Extend checks and, in PV nodes, also dangerous moves
if (PvNode && dangerous)
&& pos.pl_move_is_legal(move, ci.pinned)
&& abs(ttValue) < VALUE_KNOWN_WIN)
{
+ assert(ttValue != VALUE_NONE);
+
Value rBeta = ttValue - int(depth);
ss->excludedMove = move;
ss->skipNullMove = true;
&& !inCheck
&& !dangerous
&& move != ttMove
- && (bestValue > VALUE_MATED_IN_MAX_PLY || bestValue == -VALUE_INFINITE))
+ && (bestValue > VALUE_MATED_IN_MAX_PLY || ( bestValue == -VALUE_INFINITE
+ && alpha > VALUE_MATED_IN_MAX_PLY)))
{
// Move count based pruning
if ( depth < 16 * ONE_PLY
if (PvNode && value < beta)
{
alpha = value; // Update alpha here! Always alpha < beta
- if (SpNode) sp->alpha = alpha;
+ if (SpNode) sp->alpha = value;
}
else // Fail high
{
// If we are in a singular extension search then return a fail low score.
// A split node has at least one move, the one tried before to be splitted.
if (!moveCount)
- return excludedMove ? alpha : inCheck ? mated_in(ss->ply) : VALUE_DRAW;
+ return excludedMove ? alpha
+ : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
// If we have pruned all the moves without searching return a fail-low score
if (bestValue == -VALUE_INFINITE)
assert(NT == PV || NT == NonPV);
assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
- assert((alpha == beta - 1) || PvNode);
+ assert(PvNode || (alpha == beta - 1));
assert(depth <= DEPTH_ZERO);
StateInfo st;
- Move ttMove, move, bestMove;
- Value ttValue, bestValue, value, evalMargin, futilityValue, futilityBase;
- bool inCheck, enoughMaterial, givesCheck, evasionPrunable;
const TTEntry* tte;
+ Key posKey;
+ Move ttMove, move, bestMove;
+ Value bestValue, value, ttValue, futilityValue, futilityBase;
+ bool inCheck, givesCheck, enoughMaterial, evasionPrunable;
Depth ttDepth;
- Bound bt;
- Value oldAlpha = alpha;
+ inCheck = pos.in_check();
ss->currentMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
// Check for an instant draw or maximum ply reached
if (pos.is_draw<true>() || ss->ply > MAX_PLY)
- return Eval::ValueDraw[pos.side_to_move()];
-
- // Decide whether or not to include checks, this fixes also the type of
- // TT entry depth that we are going to use. Note that in qsearch we use
- // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
- inCheck = pos.in_check();
- ttDepth = (inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS);
+ return DrawValue[pos.side_to_move()];
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
- tte = TT.probe(pos.key());
- ttMove = (tte ? tte->move() : MOVE_NONE);
- ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_ZERO;
+ posKey = pos.key();
+ tte = TT.probe(posKey);
+ ttMove = tte ? tte->move() : MOVE_NONE;
+ ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE;
- if (!PvNode && tte && can_return_tt(tte, ttDepth, ttValue, beta))
+ // Decide whether or not to include checks, this fixes also the type of
+ // TT entry depth that we are going to use. Note that in qsearch we use
+ // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
+ ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
+ : DEPTH_QS_NO_CHECKS;
+ if ( tte && tte->depth() >= ttDepth
+ && ( PvNode ? tte->type() == BOUND_EXACT
+ : ttValue >= beta ? (tte->type() & BOUND_LOWER)
+ : (tte->type() & BOUND_UPPER)))
{
+ assert(ttValue != VALUE_NONE); // Due to ttDepth > DEPTH_NONE
+
ss->currentMove = ttMove; // Can be MOVE_NONE
return ttValue;
}
// Evaluate the position statically
if (inCheck)
{
+ ss->eval = ss->evalMargin = VALUE_NONE;
bestValue = futilityBase = -VALUE_INFINITE;
- ss->eval = evalMargin = VALUE_NONE;
enoughMaterial = false;
}
else
{
assert(tte->static_value() != VALUE_NONE);
- evalMargin = tte->static_value_margin();
ss->eval = bestValue = tte->static_value();
+ ss->evalMargin = tte->static_value_margin();
}
else
- ss->eval = bestValue = evaluate(pos, evalMargin);
+ ss->eval = bestValue = evaluate(pos, ss->evalMargin);
// Stand pat. Return immediately if static value is at least beta
if (bestValue >= beta)
{
if (!tte)
- TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin);
+ TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER,
+ DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin);
return bestValue;
}
if (PvNode && bestValue > alpha)
alpha = bestValue;
- futilityBase = ss->eval + evalMargin + Value(128);
+ futilityBase = ss->eval + ss->evalMargin + Value(128);
enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMg;
}
CheckInfo ci(pos);
// Loop through the moves until no moves remain or a beta cutoff occurs
- while ( bestValue < beta
- && (move = mp.next_move<false>()) != MOVE_NONE)
+ while ((move = mp.next_move<false>()) != MOVE_NONE)
{
assert(is_ok(move));
// Make and search the move
pos.do_move(move, st, ci, givesCheck);
- value = -qsearch<NT>(pos, ss+1, -beta, -alpha, depth-ONE_PLY);
+ value = -qsearch<NT>(pos, ss+1, -beta, -alpha, depth - ONE_PLY);
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- // New best move?
+ // Check for new best move
if (value > bestValue)
{
bestValue = value;
- bestMove = move;
- if ( PvNode
- && value > alpha
- && value < beta) // We want always alpha < beta
- alpha = value;
+ if (value > alpha)
+ {
+ if (PvNode && value < beta) // Update alpha here! Always alpha < beta
+ {
+ alpha = value;
+ bestMove = move;
+ }
+ else // Fail high
+ {
+ TT.store(posKey, value_to_tt(value, ss->ply), BOUND_LOWER,
+ ttDepth, move, ss->eval, ss->evalMargin);
+
+ return value;
+ }
+ }
}
}
if (inCheck && bestValue == -VALUE_INFINITE)
return mated_in(ss->ply); // Plies to mate from the root
- // Update transposition table
- move = bestValue <= oldAlpha ? MOVE_NONE : bestMove;
- bt = bestValue <= oldAlpha ? BOUND_UPPER
- : bestValue >= beta ? BOUND_LOWER : BOUND_EXACT;
-
- TT.store(pos.key(), value_to_tt(bestValue, ss->ply), bt, ttDepth, move, ss->eval, evalMargin);
+ TT.store(posKey, value_to_tt(bestValue, ss->ply),
+ PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER,
+ ttDepth, bestMove, ss->eval, ss->evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
Value value_to_tt(Value v, int ply) {
- if (v >= VALUE_MATE_IN_MAX_PLY)
- return v + ply;
+ assert(v != VALUE_NONE);
- if (v <= VALUE_MATED_IN_MAX_PLY)
- return v - ply;
-
- return v;
+ return v >= VALUE_MATE_IN_MAX_PLY ? v + ply
+ : v <= VALUE_MATED_IN_MAX_PLY ? v - ply : v;
}
Value value_from_tt(Value v, int ply) {
- if (v >= VALUE_MATE_IN_MAX_PLY)
- return v - ply;
-
- if (v <= VALUE_MATED_IN_MAX_PLY)
- return v + ply;
-
- return v;
+ return v == VALUE_NONE ? VALUE_NONE
+ : v >= VALUE_MATE_IN_MAX_PLY ? v - ply
+ : v <= VALUE_MATED_IN_MAX_PLY ? v + ply : v;
}
}
- // can_return_tt() returns true if a transposition table score can be used to
- // cut-off at a given point in search.
-
- bool can_return_tt(const TTEntry* tte, Depth depth, Value v, Value beta) {
-
- return ( tte->depth() >= depth
- || v >= std::max(VALUE_MATE_IN_MAX_PLY, beta)
- || v < std::min(VALUE_MATED_IN_MAX_PLY, beta))
-
- && ( ((tte->type() & BOUND_LOWER) && v >= beta)
- || ((tte->type() & BOUND_UPPER) && v < beta));
- }
-
-
// refine_eval() returns the transposition table score if possible, otherwise
- // falls back on static position evaluation.
+ // falls back on static position evaluation. Note that we never return VALUE_NONE
+ // even if v == VALUE_NONE.
Value refine_eval(const TTEntry* tte, Value v, Value defaultEval) {
assert(tte);
+ assert(v != VALUE_NONE || !tte->type());
if ( ((tte->type() & BOUND_LOWER) && v >= defaultEval)
|| ((tte->type() & BOUND_UPPER) && v < defaultEval))
projects / stockfish / blobdiff