const bool PruneDefendingMoves = false;
const bool PruneBlockingMoves = false;
+ // Only move margin
+ const Value OnlyMoveMargin = Value(100);
+
// Margins for futility pruning in the quiescence search, and at frontier
// and near frontier nodes.
const Value FutilityMarginQS = Value(0x80);
// Each move futility margin is decreased
- const Value IncrementalFutilityMargin = Value(0xA);
+ const Value IncrementalFutilityMargin = Value(0x8);
// Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply
const Value FutilityMargins[12] = { Value(0x100), Value(0x120), Value(0x200), Value(0x220), Value(0x250), Value(0x270),
Value id_loop(const Position& pos, Move searchMoves[]);
Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta);
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);
+ Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move forbiddenMove = MOVE_NONE);
Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
void sp_search(SplitPoint* sp, int threadID);
void sp_search_pv(SplitPoint* sp, int threadID);
moveIsCheck = pos.move_is_check(move, ci);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
- movesSearched[moveCount++] = ss[ply].currentMove = move;
+ movesSearched[moveCount++] = move;
// Decide the new search depth
ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
+
+ // Only move extension
+ if ( moveCount == 1
+ && ext < OnePly
+ && depth >= 4 * OnePly
+ && tte
+ && (tte->type() & VALUE_TYPE_LOWER)
+ && tte->move() != MOVE_NONE
+ && tte->depth() >= depth - 3 * OnePly)
+ {
+ Value ttValue = value_from_tt(tte->value(), ply);
+ if (abs(ttValue) < VALUE_KNOWN_WIN)
+ {
+ Value excValue = search(pos, ss, ttValue - OnlyMoveMargin, Max(Min(depth / 2, depth - 4 * OnePly), OnePly), ply, false, threadID, tte->move());
+ if (excValue < ttValue - OnlyMoveMargin)
+ ext = OnePly;
+ }
+ }
+
newDepth = depth - OnePly + ext;
+ // Update current move
+ ss[ply].currentMove = move;
+
// Make and search the move
pos.do_move(move, st, ci, moveIsCheck);
// search() is the search function for zero-width nodes.
Value search(Position& pos, SearchStack ss[], Value beta, Depth depth,
- int ply, bool allowNullmove, int threadID) {
+ int ply, bool allowNullmove, int threadID, Move forbiddenMove) {
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
if (value_mate_in(ply + 1) < beta)
return beta - 1;
+ // Position key calculation
+ Key posKey = pos.get_key();
+
+ if (forbiddenMove != MOVE_NONE)
+ posKey ^= Position::zobExclusion;
+
// Transposition table lookup
- tte = TT.retrieve(pos.get_key());
+ tte = TT.retrieve(posKey);
ttMove = (tte ? tte->move() : MOVE_NONE);
if (tte && ok_to_use_TT(tte, depth, beta, ply))
{
assert(move_is_ok(move));
+ if (move == forbiddenMove)
+ continue;
+
singleReply = (isCheck && mp.number_of_evasions() == 1);
moveIsCheck = pos.move_is_check(move, ci);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
- movesSearched[moveCount++] = ss[ply].currentMove = move;
+ movesSearched[moveCount++] = move;
// Decide the new search depth
ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
+
+ // Only move extension
+ if ( forbiddenMove == MOVE_NONE
+ && moveCount == 1
+ && ext < OnePly
+ && depth >= 4 * OnePly
+ && tte
+ && (tte->type() & VALUE_TYPE_LOWER)
+ && tte->move() != MOVE_NONE
+ && tte->depth() >= depth - 3 * OnePly)
+ {
+ Value ttValue = value_from_tt(tte->value(), ply);
+ if (abs(ttValue) < VALUE_KNOWN_WIN)
+ {
+ Value excValue = search(pos, ss, ttValue - OnlyMoveMargin, Max(Min(depth / 2, depth - 4 * OnePly), OnePly), ply, false, threadID, tte->move());
+ if (excValue < ttValue - OnlyMoveMargin)
+ ext = (depth >= 8 * OnePly)? OnePly : ext + OnePly / 2;
+ }
+ }
+
newDepth = depth - OnePly + ext;
+ // Update current move
+ ss[ply].currentMove = move;
+
// Futility pruning
if ( useFutilityPruning
&& !dangerous
{
//std::cout << std::endl;
//for (int d = 2; d < 14; d++)
- // std::cout << d << ", " << 300 + 2*(1 << (3*d/4)) << std::endl;
+ // std::cout << d << ", " << 64*(1+bitScanReverse32(d*d)) << std::endl;
//std::cout << std::endl;
/*
+ 64*(1+bitScanReverse32(d*d))
+
+ 2 -> 256 - 256
+ 3 -> 288 - 320
+ 4 -> 512 - 384
+ 5 -> 544 - 384
+ 6 -> 592 - 448
+ 7 -> 624 - 448
+ 8 -> 672 - 512
+ 9 -> 704 - 512
+ 10 -> 832 - 512
+ 11 -> 864 - 512
+ 12 -> 928 - 576
+ 13 -> 960 - 576
+
300 + 2*(1 << (3*d/4))
2 -> 256 - 304
{
if (futilityValue == VALUE_NONE)
futilityValue = evaluate(pos, ei, threadID)
- + (300 + 2 * (1 << (3 * int(depth) /4)))
- + 4*IncrementalFutilityMargin;
+ + 64*(2+bitScanReverse32(int(depth) * int(depth)));
futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin;
// All legal moves have been searched. A special case: If there were
// no legal moves, it must be mate or stalemate.
if (moveCount == 0)
- return (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
+ return (forbiddenMove == MOVE_NONE ? (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW) : beta - 1);
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
return bestValue;
if (bestValue < beta)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE);
+ TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE);
else
{
BetaCounter.add(pos.side_to_move(), depth, threadID);
update_history(pos, move, depth, movesSearched, moveCount);
update_killers(move, ss[ply]);
}
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
+ TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
}
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
projects / stockfish / blobdiff