namespace {
enum MovegenPhase {
- PH_TT_MOVES, // Transposition table move and mate killer
+ PH_TT_MOVE, // Transposition table move
PH_GOOD_CAPTURES, // Queen promotions and captures with SEE values >= 0
PH_KILLERS, // Killer moves from the current ply
PH_NONCAPTURES, // Non-captures and underpromotions
};
CACHE_LINE_ALIGNMENT
- const uint8_t MainSearchTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP };
- const uint8_t EvasionTable[] = { PH_TT_MOVES, PH_EVASIONS, PH_STOP };
- const uint8_t QsearchWithChecksTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP };
- const uint8_t QsearchWithoutChecksTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP };
+ 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 };
}
bool MovePicker::isBadCapture() const { return phase == PH_BAD_CAPTURES; }
-/// Constructor for the MovePicker class. Apart from the position for which
-/// it is asked to pick legal moves, MovePicker also wants some information
+/// Constructor for 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 about how important good
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
SearchStack* ss, Value beta) : pos(p), H(h) {
- int searchTT = ttm;
- ttMoves[0].move = ttm;
badCaptureThreshold = 0;
badCaptures = moves + MAX_MOVES;
if (p.in_check())
{
- ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE;
+ killers[0].move = killers[1].move = MOVE_NONE;
phasePtr = EvasionTable;
}
else
{
- ttMoves[1].move = (ss->mateKiller == ttm) ? MOVE_NONE : ss->mateKiller;
- searchTT |= ttMoves[1].move;
killers[0].move = ss->killers[0];
killers[1].move = ss->killers[1];
phasePtr = MainSearchTable;
}
- phasePtr += int(!searchTT) - 1;
+ ttMove = (ttm && pos.move_is_pl(ttm) ? ttm : MOVE_NONE);
+ phasePtr += int(ttMove == MOVE_NONE) - 1;
go_next_phase();
}
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h)
: pos(p), H(h) {
- int searchTT = ttm;
- ttMoves[0].move = ttm;
- ttMoves[1].move = MOVE_NONE;
assert(d <= DEPTH_ZERO);
// 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))
- searchTT = ttMoves[0].move = MOVE_NONE;
+ ttm = MOVE_NONE;
}
- phasePtr += int(!searchTT) - 1;
+ ttMove = (ttm && pos.move_is_pl(ttm) ? ttm : MOVE_NONE);
+ phasePtr += int(ttMove == MOVE_NONE) - 1;
go_next_phase();
}
phase = *(++phasePtr);
switch (phase) {
- case PH_TT_MOVES:
- curMove = ttMoves;
- lastMove = curMove + 2;
+ case PH_TT_MOVE:
+ lastMove = curMove + 1;
return;
case PH_GOOD_CAPTURES:
}
/// MovePicker::get_next_move() is the most important method of the MovePicker
-/// class. It returns a new legal move every time it is called, until there
+/// 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
switch (phase) {
- case PH_TT_MOVES:
- move = (curMove++)->move;
- if ( move != MOVE_NONE
- && pos.move_is_pl(move))
- return move;
+ case PH_TT_MOVE:
+ curMove++;
+ return ttMove;
break;
case PH_GOOD_CAPTURES:
move = pick_best(curMove++, lastMove).move;
- if ( move != ttMoves[0].move
- && move != ttMoves[1].move)
+ if (move != ttMove)
{
// Check for a non negative SEE now
int seeValue = pos.see_sign(move);
return move;
// Losing capture, move it to the tail of the array, note
- // that move has now been already checked for legality.
+ // that move has now been already checked for pseudo legality.
(--badCaptures)->move = move;
badCaptures->score = seeValue;
}
move = (curMove++)->move;
if ( move != MOVE_NONE
&& pos.move_is_pl(move)
- && move != ttMoves[0].move
- && move != ttMoves[1].move
+ && move != ttMove
&& !pos.move_is_capture(move))
return move;
break;
insertion_sort<MoveStack>(lastGoodNonCapture, lastMove);
move = (curMove++)->move;
- if ( move != ttMoves[0].move
- && move != ttMoves[1].move
+ if ( move != ttMove
&& move != killers[0].move
&& move != killers[1].move)
return move;
case PH_EVASIONS:
case PH_QCAPTURES:
move = pick_best(curMove++, lastMove).move;
- if (move != ttMoves[0].move)
+ if (move != ttMove)
return move;
break;
case PH_QCHECKS:
move = (curMove++)->move;
- if ( move != ttMoves[0].move)
+ if (move != ttMove)
return move;
break;