kate/BadFish
1
0
Fork 0
mirror of https://github.com/sockspls/badfish synced 2025-04-30 00:33:09 +00:00
Code Issues Releases Wiki Activity

Try only recaptures in qsearch if depth is very low

Browse source 
This avoids search explosion in qsearch for some
patological cases like:

r1n1n1b1/1P1P1P1P/1N1N1N2/2RnQrRq/2pKp3/3BNQbQ/k7/4Bq2 w - - 0 1

After 9078 games 20"+0.1 QUAD:
Mod vs Orig 1413 - 1319 - 6346 ELO +3 (+- 4)

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2011-06-12 07:25:51 +01:00
parent 15683034a7
commit 72760c05c6
4 changed files with 27 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
src/movepick.cpp
View file

@ -37,6 +37,7 @@ namespace {
PH_BAD_CAPTURES, // Queen promotions and captures with SEE values < captureThreshold (captureThreshold <= 0)
PH_EVASIONS, // Check evasions
PH_QCAPTURES, // Captures in quiescence search
PH_QRECAPTURES, // Recaptures in quiescence search
PH_QCHECKS, // Non-capture checks in quiescence search
PH_STOP
};
@ -46,6 +47,7 @@ namespace {
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 QsearchRecapturesTable[] = { PH_TT_MOVE, PH_QRECAPTURES, PH_STOP };
const uint8_t ProbCutTable[] = { PH_TT_MOVE, PH_GOOD_PROBCUT, PH_STOP };
}
@ -85,7 +87,7 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
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);
@ -94,7 +96,7 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h)
phasePtr = EvasionTable;
else if (d >= DEPTH_QS_CHECKS)
phasePtr = QsearchWithChecksTable;
else
else if (d >= DEPTH_QS_RECAPTURES)
{
phasePtr = QsearchWithoutChecksTable;
@ -104,6 +106,12 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h)
if (ttm != MOVE_NONE && !pos.move_is_capture(ttm) && !move_is_promotion(ttm))
ttm = MOVE_NONE;
}
else
{
phasePtr = QsearchRecapturesTable;
recaptureSquare = recaptureSq;
ttm = MOVE_NONE;
}
ttMove = (ttm && pos.move_is_pl(ttm) ? ttm : MOVE_NONE);
phasePtr += int(ttMove == MOVE_NONE) - 1;
@ -184,6 +192,10 @@ void MovePicker::go_next_phase() {
score_captures();
return;
case PH_QRECAPTURES:
lastMove = generate<MV_CAPTURE>(pos, moves);
return;
case PH_QCHECKS:
lastMove = generate<MV_NON_CAPTURE_CHECK>(pos, moves);
return;
@ -347,6 +359,12 @@ Move MovePicker::get_next_move() {
return move;
break;
case PH_QRECAPTURES:
move = (curMove++)->move;
if (move_to(move) == recaptureSquare)
return move;
break;
case PH_QCHECKS:
move = (curMove++)->move;
if (move != ttMove)

3
src/movepick.h
View file

@ -41,7 +41,7 @@ class MovePicker {
public:
MovePicker(const Position&, Move, Depth, const History&, SearchStack*, Value);
MovePicker(const Position&, Move, Depth, const History&);
MovePicker(const Position&, Move, Depth, const History&, Square recaptureSq);
MovePicker(const Position&, Move, const History&, int parentCapture);
Move get_next_move();
@ -56,6 +56,7 @@ private:
Depth depth;
Move ttMove;
MoveStack killers[2];
Square recaptureSquare;
int captureThreshold, phase;
const uint8_t* phasePtr;
MoveStack *curMove, *lastMove, *lastNonCapture, *badCaptures;

2
src/search.cpp
View file

@ -1393,7 +1393,7 @@ split_point_start: // At split points actual search starts from here
// to search the moves. Because the depth is <= 0 here, only captures,
// queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
// be generated.
MovePicker mp(pos, ttMove, depth, H);
MovePicker mp(pos, ttMove, depth, H, move_to((ss-1)->currentMove));
CheckInfo ci(pos);
Bitboard pinned = pos.pinned_pieces(pos.side_to_move());

7
src/types.h
View file

@ -201,9 +201,10 @@ enum Depth {
ONE_PLY = 2,
DEPTH_ZERO = 0 * ONE_PLY,
DEPTH_QS_CHECKS = -1 * ONE_PLY,
DEPTH_QS_NO_CHECKS = -2 * ONE_PLY,
DEPTH_ZERO = 0 * ONE_PLY,
DEPTH_QS_CHECKS = -1 * ONE_PLY,
DEPTH_QS_NO_CHECKS = -2 * ONE_PLY,
DEPTH_QS_RECAPTURES = -4 * ONE_PLY,
DEPTH_NONE = -127 * ONE_PLY
};