MoveStack* generate<EVASIONS>(const Position& pos, MoveStack* mlist) {
assert(pos.checkers());
Square from, checksq;
int checkersCnt = 0;
Color us = pos.side_to_move();
Square ksq = pos.king_square(us);
Bitboard sliderAttacks = 0;
Bitboard b = pos.checkers();
assert(pos.checkers());
// Find squares attacked by slider checkers, we will remove them from the king
// evasions so to skip known illegal moves avoiding useless legality check later.
do
{
checkersCnt++;
checksq = pop_lsb(&b);
assert(color_of(pos.piece_on(checksq)) == ~us);
switch (type_of(pos.piece_on(checksq)))
{
case BISHOP: sliderAttacks |= PseudoAttacks[BISHOP][checksq]; break;
case ROOK: sliderAttacks |= PseudoAttacks[ROOK][checksq]; break;
case QUEEN:
// If queen and king are far or not on a diagonal line we can safely
// remove all the squares attacked in the other direction becuase are
// not reachable by the king anyway.
if (between_bb(ksq, checksq) || !(PseudoAttacks[BISHOP][checksq] & ksq))
sliderAttacks |= PseudoAttacks[QUEEN][checksq];
// Otherwise we need to use real rook attacks to check if king is safe
// to move in the other direction. For example: king in B2, queen in A1
// a knight in B1, and we can safely move to C1.
else
sliderAttacks |= PseudoAttacks[BISHOP][checksq] | pos.attacks_from<ROOK>(checksq);
default:
break;
}
} while (b);
// Generate evasions for king, capture and non capture moves
b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
from = ksq;
SERIALIZE(b);
if (checkersCnt > 1)
return mlist; // Double check, only a king move can save the day
// Generate blocking evasions or captures of the checking piece
Bitboard target = between_bb(checksq, ksq) | pos.checkers();
return generate_all<EVASIONS>(pos, mlist, us, target);
}
ExtMove* generate<EVASIONS>(const Position& pos, ExtMove* moveList) {
assert(pos.checkers());
Color us = pos.side_to_move();
Square ksq = pos.square<KING>(us);
Bitboard sliderAttacks = 0;
Bitboard sliders = pos.checkers() & ~pos.pieces(KNIGHT, PAWN);
// Find all the squares attacked by slider checkers. We will remove them from
// the king evasions in order to skip known illegal moves, which avoids any
// useless legality checks later on.
while (sliders)
{
Square checksq = pop_lsb(&sliders);
sliderAttacks |= LineBB[checksq][ksq] ^ checksq;
}
// Generate evasions for king, capture and non capture moves
Bitboard b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
while (b)
*moveList++ = make_move(ksq, pop_lsb(&b));
if (more_than_one(pos.checkers()))
return moveList; // Double check, only a king move can save the day
// Generate blocking evasions or captures of the checking piece
Square checksq = lsb(pos.checkers());
Bitboard target = between_bb(checksq, ksq) | checksq;
return us == WHITE ? generate_all<WHITE, EVASIONS>(pos, moveList, target)
: generate_all<BLACK, EVASIONS>(pos, moveList, target);
}
ExtMove* generate<EVASIONS>(const Position& pos, ExtMove* mlist) {
assert(pos.checkers());
int checkersCnt = 0;
Color us = pos.side_to_move();
Square ksq = pos.king_square(us), from = ksq /* For SERIALIZE */, checksq;
Bitboard sliderAttacks = 0;
Bitboard b = pos.checkers();
assert(pos.checkers());
// Find all the squares attacked by slider checkers. We will remove them from
// the king evasions in order to skip known illegal moves, which avoids any
// useless legality checks later on.
do
{
++checkersCnt;
checksq = pop_lsb(&b);
assert(color_of(pos.piece_on(checksq)) == ~us);
if (type_of(pos.piece_on(checksq)) > KNIGHT) // A slider
sliderAttacks |= LineBB[checksq][ksq] ^ checksq;
} while (b);
// Generate evasions for king, capture and non capture moves
b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
SERIALIZE(b);
if (checkersCnt > 1)
return mlist; // Double check, only a king move can save the day
// Generate blocking evasions or captures of the checking piece
Bitboard target = between_bb(checksq, ksq) | checksq;
return us == WHITE ? generate_all<WHITE, EVASIONS>(pos, mlist, target)
: generate_all<BLACK, EVASIONS>(pos, mlist, target);
}