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Use special handling for promotions in move_is_legal()

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Simplifies a bit the code and the common case too.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-10-03 11:10:08 +01:00
parent 98b09b4038
commit 544adf7e41
1 changed files with 8 additions and 15 deletions
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23
src/movegen.cpp
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@ -335,7 +335,7 @@ bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) {
Piece pc = pos.piece_on(from); Piece pc = pos.piece_on(from);
// Use a slower but simpler function for uncommon cases // Use a slower but simpler function for uncommon cases
if (move_is_ep(m) || move_is_castle(m)) if (move_is_special(m))
return move_is_legal(pos, m); return move_is_legal(pos, m);
// If the from square is not occupied by a piece belonging to the side to // If the from square is not occupied by a piece belonging to the side to
@ -355,14 +355,9 @@ bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) {
if ((us == WHITE) != (direction > 0)) if ((us == WHITE) != (direction > 0))
return false; return false;
// A pawn move is a promotion iff the destination square is // We have already handled promotion moves, so destination
// on the 8/1th rank. // cannot be on the 8/1th rank.
if (( (square_rank(to) == RANK_8 && us == WHITE) if (square_rank(to) == RANK_8 || square_rank(to) == RANK_1)
||(square_rank(to) == RANK_1 && us != WHITE)) != bool(move_is_promotion(m)))
return false;
// The promotion piece, if any, must be valid
if (move_promotion_piece(m) > QUEEN || move_promotion_piece(m) == PAWN)
return false; return false;
// Proceed according to the square delta between the origin and // Proceed according to the square delta between the origin and
@ -409,14 +404,12 @@ bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) {
default: default:
return false; return false;
} }
// The move is pseudo-legal, check if it is also legal
return pos.is_check() ? pos.pl_move_is_evasion(m, pinned) : pos.pl_move_is_legal(m, pinned);
} }
else if (!bit_is_set(pos.attacks_from(pc, from), to))
return false;
// Luckly we can handle all the other pieces in one go // The move is pseudo-legal, check if it is also legal
return bit_is_set(pos.attacks_from(pc, from), to) return pos.is_check() ? pos.pl_move_is_evasion(m, pinned) : pos.pl_move_is_legal(m, pinned);
&& (pos.is_check() ? pos.pl_move_is_evasion(m, pinned) : pos.pl_move_is_legal(m, pinned))
&& !move_is_promotion(m);
} }