#include <cassert>
#include "history.h"
+#include "evaluate.h"
#include "movegen.h"
#include "movepick.h"
#include "search.h"
int MainSearchPhaseIndex;
int EvasionsPhaseIndex;
int QsearchWithChecksPhaseIndex;
+ int QsearchNoCapturesPhaseIndex;
int QsearchWithoutChecksPhaseIndex;
+ int NoMovesPhaseIndex;
}
/// search captures, promotions and some checks) and about how important good
/// move ordering is at the current node.
-MovePicker::MovePicker(const Position& p, bool pvnode, Move ttm, Move mk,
- Move k1, Move k2, Depth d) : pos(p) {
- pvNode = pvnode;
+MovePicker::MovePicker(const Position& p, bool pv, Move ttm,
+ Move mk, Move k1, Move k2, Depth d, EvalInfo* ei) : pos(p) {
+ pvNode = pv;
ttMove = ttm;
mateKiller = (mk == ttm)? MOVE_NONE : mk;
killer1 = k1;
movesPicked = 0;
numOfMoves = 0;
numOfBadCaptures = 0;
- dc = p.discovered_check_candidates(p.side_to_move());
+
+ // With EvalInfo we are able to know how many captures are possible before
+ // generating them. So avoid generating them in case we know are zero.
+ Color us = pos.side_to_move();
+ Color them = opposite_color(us);
+ bool noAttacks = ei && (ei->attackedBy[us][0] & pos.pieces_of_color(them)) == 0;
+ bool noCaptures = noAttacks && (pos.ep_square() == SQ_NONE) && !pos.has_pawn_on_7th(us);
if (p.is_check())
- phaseIndex = EvasionsPhaseIndex;
+ phaseIndex = EvasionsPhaseIndex;
else if (depth > Depth(0))
- phaseIndex = MainSearchPhaseIndex;
+ phaseIndex = MainSearchPhaseIndex;
else if (depth == Depth(0))
- phaseIndex = QsearchWithChecksPhaseIndex;
+ phaseIndex = (noCaptures ? QsearchNoCapturesPhaseIndex : QsearchWithChecksPhaseIndex);
else
- phaseIndex = QsearchWithoutChecksPhaseIndex;
+ phaseIndex = (noCaptures ? NoMovesPhaseIndex : QsearchWithoutChecksPhaseIndex);
+
+ dc = p.discovered_check_candidates(us);
pinned = p.pinned_pieces(p.side_to_move());
finished = false;
// Suprisingly, this appears to perform slightly better than SEE based
// move ordering. The reason is probably that in a position with a winning
// capture, capturing a more valuable (but sufficiently defended) piece
- // first usually doesn't hurt. The opponent will have to recapture, and
+ // first usually doesn't hurt. The opponent will have to recapture, and
// the hanging piece will still be hanging (except in the unusual cases
// where it is possible to recapture with the hanging piece). Exchanging
// big pieces before capturing a hanging piece probably helps to reduce
- // the subtree size. Instead of calculating SEE here to filter out
- // loosing captures, we delay the filtering in pick_move_from_list()
+ // the subtree size.
+ // While scoring captures it moves all captures with negative SEE values
+ // to the badCaptures[] array.
Move m;
+ int seeValue;
for (int i = 0; i < numOfMoves; i++)
{
m = moves[i].move;
- if (move_promotion(m))
- moves[i].score = QueenValueMidgame;
+ seeValue = pos.see(m);
+ if (seeValue >= 0)
+ {
+ if (move_promotion(m))
+ moves[i].score = QueenValueMidgame;
+ else
+ moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
+ -int(pos.type_of_piece_on(move_from(m)));
+ }
else
- moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
- -int(pos.type_of_piece_on(move_from(m)));
+ {
+ // Losing capture, move it to the badCaptures[] array
+ assert(numOfBadCaptures < 63);
+ moves[i].score = seeValue;
+ badCaptures[numOfBadCaptures++] = moves[i];
+ moves[i--] = moves[--numOfMoves];
+ }
}
}
}
-/// find_best_index() loops across the moves and returns index of
-/// the highest scored one.
+/// find_best_index() loops across the moves and returns index of\r
+/// the highest scored one. There is also a second version that\r
+/// lowers the priority of moves that attack the same square,\r
+/// so that if the best move that attack a square fails the next\r
+/// move picked attacks a different square if any, not the same one.
int MovePicker::find_best_index() {
return bestIndex;
}
+int MovePicker::find_best_index(Bitboard* squares, int values[]) {\r
+\r
+ int hs;\r
+ Move m;\r
+ Square to;\r
+ int bestScore = -10000000, bestIndex = -1;\r
+\r
+ for (int i = movesPicked; i < numOfMoves; i++)\r
+ {\r
+ m = moves[i].move;\r
+ to = move_to(m);\r
+ \r
+ if (!bit_is_set(*squares, to))\r
+ {\r
+ // Init at first use\r
+ set_bit(squares, to);\r
+ values[to] = 0;\r
+ }\r
+\r
+ hs = moves[i].score - values[to];\r
+ if (hs > bestScore)\r
+ {\r
+ bestIndex = i;\r
+ bestScore = hs;\r
+ }\r
+ }\r
+\r
+ if (bestIndex != -1)\r
+ {\r
+ // Raise value of the picked square, so next attack\r
+ // to the same square will get low priority.\r
+ to = move_to(moves[bestIndex].move);\r
+ values[to] += 0xB00;\r
+ }\r
+ return bestIndex;\r
+}
+
/// MovePicker::pick_move_from_list() picks the move with the biggest score
/// from a list of generated moves (moves[] or badCaptures[], depending on
/// the current move generation phase). It takes care not to return the
/// transposition table move if that has already been serched previously.
-/// While picking captures in the PH_GOOD_CAPTURES phase (i.e. while picking
-/// non-losing captures in the main search), it moves all captures with
-/// negative SEE values to the badCaptures[] array.
Move MovePicker::pick_move_from_list() {
{
bestIndex = find_best_index();
- if (bestIndex != -1) // Found a possibly good capture
+ if (bestIndex != -1) // Found a good capture
{
move = moves[bestIndex].move;
- int seeValue = pos.see(move);
- if (seeValue < 0)
- {
- // Losing capture, move it to the badCaptures[] array
- assert(numOfBadCaptures < 63);
- moves[bestIndex].score = seeValue;
- badCaptures[numOfBadCaptures++] = moves[bestIndex];
- moves[bestIndex] = moves[--numOfMoves];
- continue;
- }
moves[bestIndex] = moves[movesPicked++];
if ( move != ttMove
&& move != mateKiller
/// MovePicker::init_phase_table() initializes the PhaseTable[],
/// MainSearchPhaseIndex, EvasionPhaseIndex, QsearchWithChecksPhaseIndex
-/// and QsearchWithoutChecksPhaseIndex variables. It is only called once
-/// during program startup, and never again while the program is running.
+/// QsearchNoCapturesPhaseIndex, QsearchWithoutChecksPhaseIndex and
+/// NoMovesPhaseIndex variables. It is only called once during program
+/// startup, and never again while the program is running.
void MovePicker::init_phase_table() {
PhaseTable[i++] = PH_QCHECKS;
PhaseTable[i++] = PH_STOP;
+ // Quiescence search with checks only and no captures
+ QsearchNoCapturesPhaseIndex = i - 1;
+ PhaseTable[i++] = PH_QCHECKS;
+ PhaseTable[i++] = PH_STOP;
+
// Quiescence search without checks
QsearchWithoutChecksPhaseIndex = i - 1;
PhaseTable[i++] = PH_QCAPTURES;
PhaseTable[i++] = PH_STOP;
+
+ // Do not generate any move
+ NoMovesPhaseIndex = i - 1;
+ PhaseTable[i++] = PH_STOP;
}
projects / stockfish / blobdiff