QSEARCH_RECAPTURES, QRECAPTURES
};
- // Our insertion sort, which is guaranteed to be stable, as it should be
- void insertion_sort(ExtMove* begin, ExtMove* end)
+ // An insertion sort, which sorts moves in descending order up to and including a given limit.
+ // The order of moves smaller than the limit is left unspecified.
+ // To keep the implementation simple, *begin is always included in the list of sorted moves.
+ void partial_insertion_sort(ExtMove* begin, ExtMove* end, Value limit)
{
- ExtMove tmp, *p, *q;
-
- for (p = begin + 1; p < end; ++p)
- {
- tmp = *p;
- for (q = p; q != begin && *(q-1) < tmp; --q)
- *q = *(q-1);
- *q = tmp;
- }
+ for (ExtMove *sortedEnd = begin + 1, *p = begin + 1; p < end; ++p)
+ if (p->value >= limit)
+ {
+ ExtMove tmp = *p, *q;
+ *p = *sortedEnd;
+ for (q = sortedEnd; q != begin && *(q-1) < tmp; --q)
+ *q = *(q-1);
+ *q = tmp;
+ ++sortedEnd;
+ }
}
// pick_best() finds the best move in the range (begin, end) and moves it to
const HistoryStats& history = pos.this_thread()->history;
- const CounterMoveStats* cmh = (ss-1)->counterMoves;
- const CounterMoveStats* fmh = (ss-2)->counterMoves;
- const CounterMoveStats* fmh2 = (ss-4)->counterMoves;
+ const CounterMoveStats& cmh = *(ss-1)->counterMoves;
+ const CounterMoveStats& fmh = *(ss-2)->counterMoves;
+ const CounterMoveStats& fm2 = *(ss-4)->counterMoves;
Color c = pos.side_to_move();
for (auto& m : *this)
- m.value = (cmh ? (*cmh)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
- + (fmh ? (*fmh)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
- + (fmh2 ? (*fmh2)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
+ m.value = cmh[pos.moved_piece(m)][to_sq(m)]
+ + fmh[pos.moved_piece(m)][to_sq(m)]
+ + fm2[pos.moved_piece(m)][to_sq(m)]
+ history.get(c, m);
}
/// left. It picks the move with the biggest value from a list of generated moves
/// taking care not to return the ttMove if it has already been searched.
-Move MovePicker::next_move() {
+Move MovePicker::next_move(bool skipQuiets) {
Move move;
cur = endBadCaptures;
endMoves = generate<QUIETS>(pos, cur);
score<QUIETS>();
- 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);
+
+ partial_insertion_sort(cur, endMoves,
+ depth < 3 * ONE_PLY ? VALUE_ZERO : Value(INT_MIN));
++stage;
case QUIET:
- while (cur < endMoves)
+ while ( cur < endMoves
+ && (!skipQuiets || cur->value >= VALUE_ZERO))
{
move = *cur++;
+
if ( move != ttMove
&& move != ss->killers[0]
&& move != ss->killers[1]