Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
namespace {
enum Stages {
- MAIN_SEARCH, GOOD_CAPTURES, KILLERS, GOOD_QUIETS, BAD_QUIETS, BAD_CAPTURES,
+ MAIN_SEARCH, GOOD_CAPTURES, KILLERS, QUIET, BAD_CAPTURES,
EVASION, ALL_EVASIONS,
QSEARCH_WITH_CHECKS, QCAPTURES_1, CHECKS,
QSEARCH_WITHOUT_CHECKS, QCAPTURES_2,
// pick_best() finds the best move in the range (begin, end) and moves it to
// the front. It's faster than sorting all the moves in advance when there
- // are few moves e.g. the possible captures.
+ // are few moves, e.g., the possible captures.
Move pick_best(ExtMove* begin, ExtMove* end)
{
std::swap(*begin, *std::max_element(begin, end));
/// Constructors of the MovePicker class. As arguments we pass information
/// to help it to return the (presumably) good moves first, to decide which
/// moves to return (in the quiescence search, for instance, we only want to
-/// search captures, promotions and some checks) and how important good move
+/// search captures, promotions, and some checks) and how important good move
/// ordering is at the current node.
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h,
- const CounterMovesStats& cmh, Move cm, Search::Stack* s)
- : pos(p), history(h), counterMovesHistory(&cmh), ss(s), countermove(cm), depth(d) {
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Search::Stack* s)
+ : pos(p), ss(s), depth(d) {
assert(d > DEPTH_ZERO);
+ Square prevSq = to_sq((ss-1)->currentMove);
+ countermove = pos.this_thread()->counterMoves[pos.piece_on(prevSq)][prevSq];
+
stage = pos.checkers() ? EVASION : MAIN_SEARCH;
ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
endMoves += (ttMove != MOVE_NONE);
}
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
- const HistoryStats& h, Square s)
- : pos(p), history(h), counterMovesHistory(nullptr) {
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Square s)
+ : pos(p) {
assert(d <= DEPTH_ZERO);
endMoves += (ttMove != MOVE_NONE);
}
-MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, Value th)
- : pos(p), history(h), counterMovesHistory(nullptr), threshold(th) {
+MovePicker::MovePicker(const Position& p, Move ttm, Value th)
+ : pos(p), threshold(th) {
assert(!pos.checkers());
void MovePicker::score<CAPTURES>() {
// Winning and equal captures in the main search are ordered by MVV, preferring
// captures near our home rank. Surprisingly, this appears to perform slightly
- // better than SEE based move ordering: exchanging big pieces before capturing
+ // better than SEE-based move ordering: exchanging big pieces before capturing
// a hanging piece probably helps to reduce the subtree size.
- // In main search we want to push captures with negative SEE values to the
+ // In the main search we want to push captures with negative SEE values to the
// badCaptures[] array, but instead of doing it now we delay until the move
// has been picked up, saving some SEE calls in case we get a cutoff.
for (auto& m : *this)
template<>
void MovePicker::score<QUIETS>() {
+ const HistoryStats& history = pos.this_thread()->history;
+
+ const CounterMoveStats* cm = (ss-1)->counterMoves;
+ const CounterMoveStats* fm = (ss-2)->counterMoves;
+ const CounterMoveStats* f2 = (ss-4)->counterMoves;
+
for (auto& m : *this)
- m.value = history[pos.moved_piece(m)][to_sq(m)]
- + (*counterMovesHistory)[pos.moved_piece(m)][to_sq(m)];
+ m.value = history[pos.moved_piece(m)][to_sq(m)]
+ + (cm ? (*cm)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
+ + (fm ? (*fm)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
+ + (f2 ? (*f2)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO);
}
template<>
void MovePicker::score<EVASIONS>() {
- // Try winning and equal captures captures ordered by MVV/LVA, then non-captures
- // ordered by history value, then bad-captures and quiet moves with a negative
- // SEE ordered by SEE value.
+ // Try winning and equal captures ordered by MVV/LVA, then non-captures ordered
+ // by history value, then bad captures and quiet moves with a negative SEE ordered
+ // by SEE value.
+ const HistoryStats& history = pos.this_thread()->history;
Value see;
for (auto& m : *this)
}
-/// generate_next_stage() generates, scores and sorts the next bunch of moves,
+/// generate_next_stage() generates, scores, and sorts the next bunch of moves
/// when there are no more moves to try for the current stage.
void MovePicker::generate_next_stage() {
endMoves = cur + 2 + (countermove != killers[0] && countermove != killers[1]);
break;
- case GOOD_QUIETS:
- endQuiets = endMoves = generate<QUIETS>(pos, moves);
+ case QUIET:
+ endMoves = generate<QUIETS>(pos, moves);
score<QUIETS>();
- endMoves = std::partition(cur, endMoves, [](const ExtMove& m) { return m.value > VALUE_ZERO; });
- insertion_sort(cur, endMoves);
- break;
-
- case BAD_QUIETS:
- cur = endMoves;
- endMoves = endQuiets;
- if (depth >= 3 * ONE_PLY)
+ if (depth < 3 * ONE_PLY)
+ {
+ ExtMove* goodQuiet = std::partition(cur, endMoves, [](const ExtMove& m)
+ { return m.value > VALUE_ZERO; });
+ insertion_sort(cur, goodQuiet);
+ } else
insertion_sort(cur, endMoves);
break;
return move;
break;
- case GOOD_QUIETS: case BAD_QUIETS:
+ case QUIET:
move = *cur++;
if ( move != ttMove
&& move != killers[0]
projects / stockfish / blobdiff