/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2012 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/>.
*/
+#include <algorithm>
#include <cassert>
#include "movegen.h"
namespace {
- enum MovegenPhase {
- PH_TT_MOVE, // Transposition table move
- PH_GOOD_CAPTURES, // Queen promotions and captures with SEE values >= captureThreshold (captureThreshold <= 0)
- PH_GOOD_PROBCUT, // Queen promotions and captures with SEE values > captureThreshold (captureThreshold >= 0)
- PH_KILLERS, // Killer moves from the current ply
- PH_NONCAPTURES, // Non-captures and underpromotions
- PH_BAD_CAPTURES, // Queen promotions and captures with SEE values < captureThreshold (captureThreshold <= 0)
- PH_EVASIONS, // Check evasions
- PH_QCAPTURES, // Captures in quiescence search
- PH_QCHECKS, // Non-capture checks in quiescence search
- PH_STOP
+ enum Sequencer {
+ MAIN_SEARCH, TT_MOVE_S1, GOOD_CAPTURES_S1, KILLERS_S1, NONCAPTURES_1_S1,
+ NONCAPTURES_2_S1, BAD_CAPTURES_S1, STOP_S1,
+ EVASIONS, TT_MOVE_S2, EVASIONS_S2, STOP_S2,
+ CAPTURES_AND_CHECKS, TT_MOVE_S3, QCAPTURES_S3, QCHECKS_S3, STOP_S3,
+ CAPTURES, TT_MOVE_S4, QCAPTURES_S4, STOP_S4,
+ RECAPTURES, TT_MOVE_S5, RECAPTURES_S5, STOP_S5,
+ PROBCUT, TT_MOVE_S6, GOOD_CAPTURES_S6, STOP_S6
};
- CACHE_LINE_ALIGNMENT
- const uint8_t MainSearchTable[] = { PH_TT_MOVE, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP };
- const uint8_t EvasionTable[] = { PH_TT_MOVE, PH_EVASIONS, PH_STOP };
- const uint8_t QsearchWithChecksTable[] = { PH_TT_MOVE, PH_QCAPTURES, PH_QCHECKS, PH_STOP };
- const uint8_t QsearchWithoutChecksTable[] = { PH_TT_MOVE, PH_QCAPTURES, PH_STOP };
- const uint8_t ProbCutTable[] = { PH_TT_MOVE, PH_GOOD_PROBCUT, PH_STOP };
+ // Unary predicate used by std::partition to split positive scores from remaining
+ // ones so to sort separately the two sets, and with the second sort delayed.
+ inline bool has_positive_score(const MoveStack& move) { return move.score > 0; }
+
+ // Picks and pushes to the front the best move in range [firstMove, lastMove),
+ // it is faster than sorting all the moves in advance when moves are few, as
+ // normally are the possible captures.
+ inline MoveStack* pick_best(MoveStack* firstMove, MoveStack* lastMove)
+ {
+ std::swap(*firstMove, *std::max_element(firstMove, lastMove));
+ return firstMove;
+ }
}
/// Constructors for the MovePicker class. As arguments we pass information
/// move ordering is at the current node.
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
- SearchStack* ss, Value beta) : pos(p), H(h) {
+ Search::Stack* ss, Value beta) : pos(p), H(h), depth(d) {
captureThreshold = 0;
badCaptures = moves + MAX_MOVES;
if (p.in_check())
{
killers[0].move = killers[1].move = MOVE_NONE;
- phasePtr = EvasionTable;
+ phase = EVASIONS;
}
else
{
killers[0].move = ss->killers[0];
killers[1].move = ss->killers[1];
- // Consider sligtly negative captures as good if at low
- // depth and far from beta.
+ // Consider sligtly negative captures as good if at low depth and far from beta
if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * ONE_PLY)
captureThreshold = -PawnValueMidgame;
- phasePtr = MainSearchTable;
+ // Consider negative captures as good if still enough to reach beta
+ else if (ss && ss->eval > beta)
+ captureThreshold = beta - ss->eval;
+
+ phase = MAIN_SEARCH;
}
- ttMove = (ttm && pos.move_is_pl(ttm) ? ttm : MOVE_NONE);
- phasePtr += int(ttMove == MOVE_NONE) - 1;
+ ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
+ phase += int(ttMove == MOVE_NONE);
go_next_phase();
}
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h)
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h, Square recaptureSq)
: pos(p), H(h) {
assert(d <= DEPTH_ZERO);
if (p.in_check())
- phasePtr = EvasionTable;
+ phase = EVASIONS;
+
else if (d >= DEPTH_QS_CHECKS)
- phasePtr = QsearchWithChecksTable;
- else
+ phase = CAPTURES_AND_CHECKS;
+
+ else if (d >= DEPTH_QS_RECAPTURES)
{
- phasePtr = QsearchWithoutChecksTable;
+ phase = CAPTURES;
// 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(ttm) && !move_is_promotion(ttm))
+ if (ttm != MOVE_NONE && !pos.is_capture_or_promotion(ttm))
ttm = MOVE_NONE;
}
+ else
+ {
+ phase = RECAPTURES;
+ recaptureSquare = recaptureSq;
+ ttm = MOVE_NONE;
+ }
- ttMove = (ttm && pos.move_is_pl(ttm) ? ttm : MOVE_NONE);
- phasePtr += int(ttMove == MOVE_NONE) - 1;
+ ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
+ phase += int(ttMove == MOVE_NONE);
go_next_phase();
}
-MovePicker::MovePicker(const Position& p, Move ttm, const History& h, int parentCapture)
+MovePicker::MovePicker(const Position& p, Move ttm, const History& h, PieceType parentCapture)
: pos(p), H(h) {
assert (!pos.in_check());
// In ProbCut we consider only captures better than parent's move
- captureThreshold = parentCapture;
- phasePtr = ProbCutTable;
+ captureThreshold = PieceValueMidgame[Piece(parentCapture)];
+ phase = PROBCUT;
if ( ttm != MOVE_NONE
- && (!pos.move_is_capture(ttm) || pos.see(ttm) <= captureThreshold))
+ && (!pos.is_capture(ttm) || pos.see(ttm) <= captureThreshold))
ttm = MOVE_NONE;
- ttMove = (ttm && pos.move_is_pl(ttm) ? ttm : MOVE_NONE);
- phasePtr += int(ttMove == MOVE_NONE) - 1;
+ ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
+ phase += int(ttMove == MOVE_NONE);
go_next_phase();
}
void MovePicker::go_next_phase() {
curMove = moves;
- phase = *(++phasePtr);
- switch (phase) {
- case PH_TT_MOVE:
+ switch (++phase) {
+
+ case TT_MOVE_S1: case TT_MOVE_S2: case TT_MOVE_S3:
+ case TT_MOVE_S4: case TT_MOVE_S5: case TT_MOVE_S6:
lastMove = curMove + 1;
return;
- case PH_GOOD_CAPTURES:
- case PH_GOOD_PROBCUT:
+ case GOOD_CAPTURES_S1:
+ case GOOD_CAPTURES_S6:
lastMove = generate<MV_CAPTURE>(pos, moves);
score_captures();
return;
- case PH_KILLERS:
+ case KILLERS_S1:
curMove = killers;
lastMove = curMove + 2;
return;
- case PH_NONCAPTURES:
- lastMove = generate<MV_NON_CAPTURE>(pos, moves);
+ case NONCAPTURES_1_S1:
+ lastNonCapture = lastMove = generate<MV_NON_CAPTURE>(pos, moves);
score_noncaptures();
- sort_moves(moves, lastMove, &lastGoodNonCapture);
+ lastMove = std::partition(curMove, lastMove, has_positive_score);
+ sort<MoveStack>(curMove, lastMove);
+ return;
+
+ case NONCAPTURES_2_S1:
+ curMove = lastMove;
+ lastMove = lastNonCapture;
+ if (depth >= 3 * ONE_PLY)
+ sort<MoveStack>(curMove, lastMove);
return;
- case PH_BAD_CAPTURES:
+ case BAD_CAPTURES_S1:
// Bad captures SEE value is already calculated so just pick
// them in order to get SEE move ordering.
curMove = badCaptures;
lastMove = moves + MAX_MOVES;
return;
- case PH_EVASIONS:
+ case EVASIONS_S2:
assert(pos.in_check());
lastMove = generate<MV_EVASION>(pos, moves);
score_evasions();
return;
- case PH_QCAPTURES:
+ case QCAPTURES_S3:
+ case QCAPTURES_S4:
lastMove = generate<MV_CAPTURE>(pos, moves);
score_captures();
return;
- case PH_QCHECKS:
+ case RECAPTURES_S5:
+ lastMove = generate<MV_CAPTURE>(pos, moves);
+ return;
+
+ case QCHECKS_S3:
lastMove = generate<MV_NON_CAPTURE_CHECK>(pos, moves);
return;
- case PH_STOP:
+ case STOP_S1: case STOP_S2: case STOP_S3:
+ case STOP_S4: case STOP_S5: case STOP_S6:
lastMove = curMove + 1; // Avoid another go_next_phase() call
return;
default:
assert(false);
- return;
}
}
/// MovePicker::score_captures(), MovePicker::score_noncaptures() and
/// MovePicker::score_evasions() assign a numerical move ordering score
/// to each move in a move list. The moves with highest scores will be
-/// picked first by get_next_move().
+/// picked first by next_move().
void MovePicker::score_captures() {
// Winning and equal captures in the main search are ordered by MVV/LVA.
for (MoveStack* cur = moves; cur != lastMove; cur++)
{
m = cur->move;
- if (move_is_promotion(m))
- cur->score = QueenValueMidgame;
- else
- cur->score = pos.midgame_value_of_piece_on(move_to(m))
- - pos.type_of_piece_on(move_from(m));
+ cur->score = PieceValueMidgame[pos.piece_on(to_sq(m))]
+ - type_of(pos.piece_moved(m));
+
+ if (is_promotion(m))
+ cur->score += PieceValueMidgame[Piece(promotion_piece_type(m))];
}
}
for (MoveStack* cur = moves; cur != lastMove; cur++)
{
m = cur->move;
- from = move_from(m);
- cur->score = H.value(pos.piece_on(from), move_to(m));
+ from = from_sq(m);
+ cur->score = H.value(pos.piece_on(from), to_sq(m));
}
}
m = cur->move;
if ((seeScore = pos.see_sign(m)) < 0)
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)) + History::MaxValue;
+ else if (pos.is_capture(m))
+ cur->score = PieceValueMidgame[pos.piece_on(to_sq(m))]
+ - type_of(pos.piece_moved(m)) + History::MaxValue;
else
- cur->score = H.value(pos.piece_on(move_from(m)), move_to(m));
+ cur->score = H.value(pos.piece_moved(m), to_sq(m));
}
}
-/// MovePicker::get_next_move() is the most important method of the MovePicker
-/// class. It returns a new pseudo legal move every time it is called, until there
+/// MovePicker::next_move() is the most important method of the MovePicker class.
+/// It returns a new pseudo legal move every time it is called, until there
/// are no more moves left. It picks the move with the biggest score from a list
/// of generated moves taking care not to return the tt move if has already been
/// searched previously. Note that this function is not thread safe so should be
/// lock protected by caller when accessed through a shared MovePicker object.
-Move MovePicker::get_next_move() {
+Move MovePicker::next_move() {
Move move;
switch (phase) {
- case PH_TT_MOVE:
+ case TT_MOVE_S1: case TT_MOVE_S2: case TT_MOVE_S3:
+ case TT_MOVE_S4: case TT_MOVE_S5: case TT_MOVE_S6:
curMove++;
return ttMove;
break;
- case PH_GOOD_CAPTURES:
- move = pick_best(curMove++, lastMove).move;
+ case GOOD_CAPTURES_S1:
+ move = pick_best(curMove++, lastMove)->move;
if (move != ttMove)
{
assert(captureThreshold <= 0); // Otherwise we must use see instead of see_sign
if (seeValue >= captureThreshold)
return move;
- // Losing capture, move it to the tail of the array, note
- // that move has now been already checked for pseudo legality.
+ // Losing capture, move it to the tail of the array
(--badCaptures)->move = move;
badCaptures->score = seeValue;
}
break;
- case PH_GOOD_PROBCUT:
- move = pick_best(curMove++, lastMove).move;
+ case GOOD_CAPTURES_S6:
+ move = pick_best(curMove++, lastMove)->move;
if ( move != ttMove
&& pos.see(move) > captureThreshold)
return move;
break;
- case PH_KILLERS:
+ case KILLERS_S1:
move = (curMove++)->move;
if ( move != MOVE_NONE
- && pos.move_is_pl(move)
+ && pos.is_pseudo_legal(move)
&& move != ttMove
- && !pos.move_is_capture(move))
+ && !pos.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);
-
+ case NONCAPTURES_1_S1:
+ case NONCAPTURES_2_S1:
move = (curMove++)->move;
if ( move != ttMove
&& move != killers[0].move
return move;
break;
- case PH_BAD_CAPTURES:
- move = pick_best(curMove++, lastMove).move;
+ case BAD_CAPTURES_S1:
+ move = pick_best(curMove++, lastMove)->move;
return move;
- case PH_EVASIONS:
- case PH_QCAPTURES:
- move = pick_best(curMove++, lastMove).move;
+ case EVASIONS_S2:
+ case QCAPTURES_S3:
+ case QCAPTURES_S4:
+ move = pick_best(curMove++, lastMove)->move;
if (move != ttMove)
return move;
break;
- case PH_QCHECKS:
+ case RECAPTURES_S5:
+ move = (curMove++)->move;
+ if (to_sq(move) == recaptureSquare)
+ return move;
+ break;
+
+ case QCHECKS_S3:
move = (curMove++)->move;
if (move != ttMove)
return move;
break;
- case PH_STOP:
+ case STOP_S1: case STOP_S2: case STOP_S3:
+ case STOP_S4: case STOP_S5: case STOP_S6:
return MOVE_NONE;
default:
assert(false);
- break;
}
}
}
projects / stockfish / blobdiff