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generate_evasions() avoid an usless check for enpassant case

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Remove ugly and useless code.
No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2009-02-11 16:51:35 +01:00
parent 1dc1cecf01
commit 214f9dcc27
1 changed files with 8 additions and 14 deletions
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22
src/movegen.cpp
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@ -322,25 +322,19 @@ int generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
to = pos.ep_square();
b1 = pos.pawn_attacks(them, to) & pos.pawns(us);
assert(b1 != EmptyBoardBB);
// The checking pawn cannot be a discovered (bishop) check candidate
// otherwise we were in check also before last double push move.
assert(!bit_is_set(pos.discovered_check_candidates(them), checksq));
assert(count_1s(b1) == 1 || count_1s(b1) == 2);
b1 &= ~pinned;
while (b1)
{
from = pop_1st_bit(&b1);
// Before generating the move, we have to make sure it is legal.
// This is somewhat tricky, because the two disappearing pawns may
// cause new "discovered checks". We test this by removing the
// two relevant bits from the occupied squares bitboard, and using
// the low-level bitboard functions for bishop and rook attacks.
b2 = pos.occupied_squares();
clear_bit(&b2, from);
clear_bit(&b2, checksq);
if (!( (bishop_attacks_bb(ksq, b2) & pos.bishops_and_queens(them))
||(rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them))))
(*mlist++).move = make_ep_move(from, to);
// Move is always legal because checking pawn is not a discovered
// check candidate and our capturing pawn has been already tested
// against pinned pieces.
(*mlist++).move = make_ep_move(from, to);
}
}
}