int generate_piece_checks(PieceType pce, const Position& pos, Bitboard target,
Bitboard dc, Square ksq, MoveStack* mlist);
+
+ inline Bitboard next_row_white(Bitboard b) { return b << 8; }
+ inline Bitboard next_row_black(Bitboard b) { return b >> 8; }
+
+ struct PawnOffsets {
+
+ Bitboard Rank3BB;
+ Bitboard Rank8BB;
+ SquareDelta DELTA_N;
+ Color them;
+ Bitboard (*next_row_fn)(Bitboard b);
+ };
+ const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, DELTA_N, BLACK, &next_row_white };
+ const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, DELTA_S, WHITE, &next_row_black };
+
+ int generate_pawn_checks(const PawnOffsets& ofs, const Position& pos, Bitboard dc,
+ Square ksq, MoveStack* mlist);
}
assert(pos.is_ok());
assert(!pos.is_check());
- Color us, them;
- Square ksq, from, to;
- Bitboard empty, b1, b2, b3;
+ Color us = pos.side_to_move();
+ Square ksq = pos.king_square(opposite_color(us));
int n = 0;
- us = pos.side_to_move();
- them = opposite_color(us);
-
- ksq = pos.king_square(them);
- assert(pos.piece_on(ksq) == king_of_color(them));
+ assert(pos.piece_on(ksq) == king_of_color(opposite_color(us)));
dc = pos.discovered_check_candidates(us);
- empty = pos.empty_squares();
-
- // Pawn moves. This is somewhat messy, and we use separate code for white
- // and black, because we can't shift by negative numbers in C/C++. :-(
-
- if (us == WHITE)
- {
- // Pawn moves which give discovered check. This is possible only if the
- // pawn is not on the same file as the enemy king, because we don't
- // generate captures.
-
- // Find all friendly pawns not on the enemy king's file
- b1 = pos.pawns(us) & ~file_bb(ksq);
-
- // Discovered checks, single pawn pushes
- b2 = b3 = ((b1 & dc) << 8) & ~Rank8BB & empty;
- while (b3)
- {
- to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - DELTA_N, to);
- }
-
- // Discovered checks, double pawn pushes
- b3 = ((b2 & Rank3BB) << 8) & empty;
- while (b3)
- {
- to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
- }
-
- // Direct checks. These are possible only for pawns on neighboring files
- // of the enemy king
-
- b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
-
- // Direct checks, single pawn pushes
- b2 = (b1 << 8) & empty;
- b3 = b2 & pos.pawn_attacks(BLACK, ksq);
- while (b3)
- {
- to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - DELTA_N, to);
- }
-
- // Direct checks, double pawn pushes
- b3 = ((b2 & Rank3BB) << 8) & empty & pos.pawn_attacks(BLACK, ksq);
- while (b3)
- {
- to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
- }
- }
- else { // (us == BLACK)
-
- // Pawn moves which give discovered check. This is possible only if the
- // pawn is not on the same file as the enemy king, because we don't
- // generate captures.
-
- // Find all friendly pawns not on the enemy king's file:
- b1 = pos.pawns(us) & ~file_bb(ksq);
-
- // Discovered checks, single pawn pushes
- b2 = b3 = ((b1 & dc) >> 8) & ~Rank1BB & empty;
- while (b3)
- {
- to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - DELTA_S, to);
- }
- // Discovered checks, double pawn pushes
- b3 = ((b2 & Rank6BB) >> 8) & empty;
- while (b3)
- {
- to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
- }
-
- // Direct checks. These are possible only for pawns on neighboring files
- // of the enemy king
-
- b1 &= (~dc & neighboring_files_bb(ksq));
-
- // Direct checks, single pawn pushes:
- b2 = (b1 >> 8) & empty;
- b3 = b2 & pos.pawn_attacks(WHITE, ksq);
- while (b3)
- {
- to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - DELTA_S, to);
- }
-
- // Direct checks, double pawn pushes
- b3 = ((b2 & Rank6BB) >> 8) & empty & pos.pawn_attacks(WHITE, ksq);
- while (b3)
- {
- to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
- }
- }
+ // Pawn moves
+ if (us == WHITE)
+ n += generate_pawn_checks(WhitePawnOffsets, pos, dc, ksq, mlist);
+ else
+ n += generate_pawn_checks(BlackPawnOffsets, pos, dc, ksq, mlist);
- // Knight moves
- b1 = pos.knights(us);
- if (b1)
- n += generate_piece_checks(KNIGHT, pos, b1, dc, ksq, mlist);
+ // Pieces moves
+ Bitboard b = pos.knights(us);
+ if (b)
+ n += generate_piece_checks(KNIGHT, pos, b, dc, ksq, mlist);
- // Bishop moves
- b1 = pos.bishops(us);
- if (b1)
- n += generate_piece_checks(BISHOP, pos, b1, dc, ksq, mlist);
+ b = pos.bishops(us);
+ if (b)
+ n += generate_piece_checks(BISHOP, pos, b, dc, ksq, mlist);
- // Rook moves
- b1 = pos.rooks(us);
- if (b1)
- n += generate_piece_checks(ROOK, pos, b1, dc, ksq, mlist);
+ b = pos.rooks(us);
+ if (b)
+ n += generate_piece_checks(ROOK, pos, b, dc, ksq, mlist);
- // Queen moves
- b1 = pos.queens(us);
- if (b1)
- n += generate_piece_checks(QUEEN, pos, b1, dc, ksq, mlist);
+ b = pos.queens(us);
+ if (b)
+ n += generate_piece_checks(QUEEN, pos, b, dc, ksq, mlist);
// King moves
- from = pos.king_square(us);
+ Square from = pos.king_square(us);
if (bit_is_set(dc, from))
{
- b1 = pos.king_attacks(from) & empty & ~QueenPseudoAttacks[ksq];
- while (b1)
+ b = pos.king_attacks(from) & pos.empty_squares() & ~QueenPseudoAttacks[ksq];
+ while (b)
{
- to = pop_1st_bit(&b1);
+ Square to = pop_1st_bit(&b);
mlist[n++].move = make_move(from, to);
}
}
}
return n;
}
+
+ int generate_pawn_checks(const PawnOffsets& ofs, const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist)
+ {
+ // Pawn moves which give discovered check. This is possible only if the
+ // pawn is not on the same file as the enemy king, because we don't
+ // generate captures.
+ int n = 0;
+ Bitboard empty = pos.empty_squares();
+
+ // Find all friendly pawns not on the enemy king's file
+ Bitboard b1 = pos.pawns(pos.side_to_move()) & ~file_bb(ksq), b2, b3;
+
+ // Discovered checks, single pawn pushes
+ b2 = b3 = (ofs.next_row_fn)(b1 & dc) & ~ofs.Rank8BB & empty;
+ while (b3)
+ {
+ Square to = pop_1st_bit(&b3);
+ mlist[n++].move = make_move(to - ofs.DELTA_N, to);
+ }
+
+ // Discovered checks, double pawn pushes
+ b3 = (ofs.next_row_fn)(b2 & ofs.Rank3BB) & empty;
+ while (b3)
+ {
+ Square to = pop_1st_bit(&b3);
+ mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
+ }
+
+ // Direct checks. These are possible only for pawns on neighboring files
+ // of the enemy king
+
+ b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
+
+ // Direct checks, single pawn pushes
+ b2 = (ofs.next_row_fn)(b1) & empty;
+ b3 = b2 & pos.pawn_attacks(ofs.them, ksq);
+ while (b3)
+ {
+ Square to = pop_1st_bit(&b3);
+ mlist[n++].move = make_move(to - ofs.DELTA_N, to);
+ }
+
+ // Direct checks, double pawn pushes
+ b3 = (ofs.next_row_fn)(b2 & ofs.Rank3BB) & empty & pos.pawn_attacks(ofs.them, ksq);
+ while (b3)
+ {
+ Square to = pop_1st_bit(&b3);
+ mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
+ }
+ return n;
+ }
}