Value bestValue, alpha, beta, delta;
memset(ss-1, 0, 4 * sizeof(Stack));
- depth = BestMoveChanges = 0;
- bestValue = delta = -VALUE_INFINITE;
(ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
+
+ depth = BestMoveChanges = 0;
+ bestValue = delta = alpha = -VALUE_INFINITE;
+ beta = VALUE_INFINITE;
+
TT.new_search();
History.clear();
Gains.clear();
// MultiPV loop. We perform a full root search for each PV line
for (PVIdx = 0; PVIdx < PVSize; PVIdx++)
{
- // Set aspiration window default width
- if (depth >= 5 && abs(RootMoves[PVIdx].prevScore) < VALUE_KNOWN_WIN)
+ // Reset aspiration window starting size
+ if (depth >= 5)
{
delta = Value(16);
- alpha = RootMoves[PVIdx].prevScore - delta;
- beta = RootMoves[PVIdx].prevScore + delta;
- }
- else
- {
- alpha = -VALUE_INFINITE;
- beta = VALUE_INFINITE;
+ alpha = std::max(RootMoves[PVIdx].prevScore - delta,-VALUE_INFINITE);
+ beta = std::min(RootMoves[PVIdx].prevScore + delta, VALUE_INFINITE);
}
// Start with a small aspiration window and, in case of fail high/low,
if (Signals.stop)
return;
- // In case of failing high/low increase aspiration window and
+ // In case of failing low/high increase aspiration window and
// research, otherwise exit the loop.
- if (bestValue > alpha && bestValue < beta)
- break;
-
- // Give some update (without cluttering the UI) before to research
- if (Time::now() - SearchTime > 3000)
- sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
-
- if (abs(bestValue) >= VALUE_KNOWN_WIN)
+ if (bestValue <= alpha)
{
- alpha = -VALUE_INFINITE;
- beta = VALUE_INFINITE;
+ alpha = std::max(bestValue - delta, -VALUE_INFINITE);
+
+ Signals.failedLowAtRoot = true;
+ Signals.stopOnPonderhit = false;
}
else if (bestValue >= beta)
- {
- beta += delta;
- delta += delta / 2;
- }
+ beta = std::min(bestValue + delta, VALUE_INFINITE);
+
else
- {
- Signals.failedLowAtRoot = true;
- Signals.stopOnPonderhit = false;
+ break;
- alpha -= delta;
- delta += delta / 2;
- }
+ delta += delta / 2;
assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
+
+ // Give some update (without cluttering the UI) before to research
+ if (Time::now() - SearchTime > 3000)
+ sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
}
// Sort the PV lines searched so far and update the GUI
// Step 5. Evaluate the position statically and update parent's gain statistics
if (inCheck)
+ {
ss->staticEval = ss->evalMargin = eval = VALUE_NONE;
+ goto iid_start;
+ }
else if (tte)
{
// Step 6. Razoring (is omitted in PV nodes)
if ( !PvNode
&& depth < 4 * ONE_PLY
- && !inCheck
&& eval + razor_margin(depth) < beta
&& ttMove == MOVE_NONE
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
if ( !PvNode
&& !ss->skipNullMove
&& depth < 4 * ONE_PLY
- && !inCheck
&& eval - futility_margin(depth, (ss-1)->futilityMoveCount) >= beta
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
&& abs(eval) < VALUE_KNOWN_WIN
if ( !PvNode
&& !ss->skipNullMove
&& depth > ONE_PLY
- && !inCheck
&& eval >= beta
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
&& pos.non_pawn_material(pos.side_to_move()))
// prune the previous move.
if ( !PvNode
&& depth >= 5 * ONE_PLY
- && !inCheck
&& !ss->skipNullMove
&& abs(beta) < VALUE_MATE_IN_MAX_PLY)
{
}
}
+iid_start: // When in check we skip early cut tests
+
// Step 10. Internal iterative deepening
if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY)
&& ttMove == MOVE_NONE
givesCheck = pos.move_gives_check(move, ci);
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));
+ || type_of(move) == CASTLE;
// Step 12. Extend checks and, in PV nodes, also dangerous moves
if (PvNode && dangerous)