/*
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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
#include <cassert>
#include "history.h"
#include "search.h"
#include "value.h"
-
-////
-//// Local definitions
-////
-
namespace {
enum MovegenPhase {
}
-////
-//// Functions
-////
-
-
/// Constructor for the MovePicker class. Apart from the position for which
/// it is asked to pick legal moves, MovePicker also wants some information
/// to help it to return the presumably good moves first, to decide which
/// search captures, promotions and some checks) and about how important good
/// move ordering is at the current node.
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
- const History& h, SearchStack* ss) : pos(p), H(h) {
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
+ SearchStack* ss, Value beta) : pos(p), H(h) {
int searchTT = ttm;
ttMoves[0].move = ttm;
- lastBadCapture = badCaptures;
+ badCaptureThreshold = 0;
+ badCaptures = moves + MOVES_MAX;
+
+ assert(d > DEPTH_ZERO);
pinned = p.pinned_pieces(pos.side_to_move());
- if (ss && !p.is_check())
+ if (p.is_check())
{
- ttMoves[1].move = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
+ ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE;
+ phasePtr = EvasionsPhaseTable;
+ }
+ else
+ {
+ ttMoves[1].move = (ss->mateKiller == ttm) ? MOVE_NONE : ss->mateKiller;
searchTT |= ttMoves[1].move;
killers[0].move = ss->killers[0];
killers[1].move = ss->killers[1];
- } else
- ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE;
+
+ // Consider sligtly negative captures as good if at low
+ // depth and far from beta.
+ if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * ONE_PLY)
+ badCaptureThreshold = -PawnValueMidgame;
+
+ phasePtr = MainSearchPhaseTable;
+ }
+
+ phasePtr += int(!searchTT) - 1;
+ go_next_phase();
+}
+
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h)
+ : pos(p), H(h) {
+ int searchTT = ttm;
+ ttMoves[0].move = ttm;
+ ttMoves[1].move = MOVE_NONE;
+
+ assert(d <= DEPTH_ZERO);
+
+ pinned = p.pinned_pieces(pos.side_to_move());
if (p.is_check())
phasePtr = EvasionsPhaseTable;
- else if (d > Depth(0))
- phasePtr = MainSearchPhaseTable;
- else if (d == Depth(0))
+ else if (d >= DEPTH_QS_CHECKS)
phasePtr = QsearchWithChecksPhaseTable;
else
+ {
phasePtr = QsearchWithoutChecksPhaseTable;
- phasePtr += !searchTT - 1;
+ // Skip TT move if is not a capture or a promotion, this avoids
+ // qsearch tree explosion due to a possible perpetual check or
+ // similar rare cases when TT table is full.
+ if (ttm != MOVE_NONE && !pos.move_is_capture_or_promotion(ttm))
+ searchTT = ttMoves[0].move = MOVE_NONE;
+ }
+
+ phasePtr += int(!searchTT) - 1;
go_next_phase();
}
return;
case PH_GOOD_CAPTURES:
- lastMove = generate_captures(pos, moves);
+ lastMove = generate<MV_CAPTURE>(pos, moves);
score_captures();
return;
return;
case PH_NONCAPTURES:
- lastMove = generate_noncaptures(pos, moves);
+ lastMove = generate<MV_NON_CAPTURE>(pos, moves);
score_noncaptures();
- sort_moves(moves, lastMove);
+ sort_moves(moves, lastMove, &lastGoodNonCapture);
return;
case PH_BAD_CAPTURES:
- // Bad captures SEE value is already calculated so just sort them
- // to get SEE move ordering.
+ // Bad captures SEE value is already calculated so just pick
+ // them in order to get SEE move ordering.
curMove = badCaptures;
- lastMove = lastBadCapture;
+ lastMove = moves + MOVES_MAX;
return;
case PH_EVASIONS:
assert(pos.is_check());
- lastMove = generate_evasions(pos, moves);
- score_evasions_or_checks();
+ lastMove = generate<MV_EVASION>(pos, moves);
+ score_evasions();
return;
case PH_QCAPTURES:
- lastMove = generate_captures(pos, moves);
+ lastMove = generate<MV_CAPTURE>(pos, moves);
score_captures();
return;
case PH_QCHECKS:
- lastMove = generate_non_capture_checks(pos, moves);
- score_evasions_or_checks();
+ lastMove = generate<MV_NON_CAPTURE_CHECK>(pos, moves);
return;
case PH_STOP:
Move m;
Piece piece;
Square from, to;
- int hs;
for (MoveStack* cur = moves; cur != lastMove; cur++)
{
from = move_from(m);
to = move_to(m);
piece = pos.piece_on(from);
- hs = H.move_ordering_score(piece, to);
-
- // Ensure history is always preferred to pst
- if (hs > 0)
- hs += 1000;
-
- // pst based scoring
- cur->score = hs + mg_value(pos.pst_delta(piece, from, to));
+ cur->score = H.value(piece, to) + H.gain(piece, to);
}
}
-void MovePicker::score_evasions_or_checks() {
+void MovePicker::score_evasions() {
// Try good captures ordered by MVV/LVA, then non-captures if
// destination square is not under attack, ordered by history
// value, and at the end bad-captures and non-captures with a
{
m = cur->move;
if ((seeScore = pos.see_sign(m)) < 0)
- cur->score = seeScore;
+ cur->score = seeScore - History::MaxValue; // Be sure we are at the bottom
else if (pos.move_is_capture(m))
cur->score = pos.midgame_value_of_piece_on(move_to(m))
- - pos.type_of_piece_on(move_from(m)) + HistoryMax;
+ - pos.type_of_piece_on(move_from(m)) + History::MaxValue;
else
- cur->score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m));
+ cur->score = H.value(pos.piece_on(move_from(m)), move_to(m));
}
}
{
// Check for a non negative SEE now
int seeValue = pos.see_sign(move);
- if (seeValue >= 0)
+ if (seeValue >= badCaptureThreshold)
return move;
- // Losing capture, move it to the badCaptures[] array, note
+ // Losing capture, move it to the tail of the array, note
// that move has now been already checked for legality.
- assert(int(lastBadCapture - badCaptures) < 63);
- lastBadCapture->move = move;
- lastBadCapture->score = seeValue;
- lastBadCapture++;
+ (--badCaptures)->move = move;
+ badCaptures->score = seeValue;
}
break;
case PH_KILLERS:
move = (curMove++)->move;
if ( move != MOVE_NONE
+ && move_is_legal(pos, move, pinned)
&& move != ttMoves[0].move
&& move != ttMoves[1].move
- && move_is_legal(pos, move, pinned)
&& !pos.move_is_capture(move))
return move;
break;
case PH_NONCAPTURES:
+
+ // Sort negative scored moves only when we get there
+ if (curMove == lastGoodNonCapture)
+ insertion_sort<MoveStack>(lastGoodNonCapture, lastMove);
+
move = (curMove++)->move;
if ( move != ttMoves[0].move
&& move != ttMoves[1].move
go_next_phase();
}
}
-
projects / stockfish / blobdiff