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movegen: Introduce generate_pawn_checks()
This greatly simplify redundant code. Perhaps slihtly slower. Test needed. Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
parent
5abe8a0816
commit
34a515f20b
1 changed files with 93 additions and 126 deletions
217
src/movegen.cpp
217
src/movegen.cpp
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@ -41,6 +41,23 @@ namespace {
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int generate_piece_checks(PieceType pce, const Position& pos, Bitboard target,
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Bitboard dc, Square ksq, MoveStack* mlist);
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inline Bitboard next_row_white(Bitboard b) { return b << 8; }
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inline Bitboard next_row_black(Bitboard b) { return b >> 8; }
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struct PawnOffsets {
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Bitboard Rank3BB;
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Bitboard Rank8BB;
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SquareDelta DELTA_N;
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Color them;
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Bitboard (*next_row_fn)(Bitboard b);
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};
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const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, DELTA_N, BLACK, &next_row_white };
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const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, DELTA_S, WHITE, &next_row_black };
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int generate_pawn_checks(const PawnOffsets& ofs, const Position& pos, Bitboard dc,
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Square ksq, MoveStack* mlist);
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}
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@ -107,146 +124,45 @@ int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
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assert(pos.is_ok());
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assert(!pos.is_check());
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Color us, them;
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Square ksq, from, to;
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Bitboard empty, b1, b2, b3;
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Color us = pos.side_to_move();
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Square ksq = pos.king_square(opposite_color(us));
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int n = 0;
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us = pos.side_to_move();
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them = opposite_color(us);
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ksq = pos.king_square(them);
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assert(pos.piece_on(ksq) == king_of_color(them));
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assert(pos.piece_on(ksq) == king_of_color(opposite_color(us)));
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dc = pos.discovered_check_candidates(us);
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empty = pos.empty_squares();
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// Pawn moves. This is somewhat messy, and we use separate code for white
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// and black, because we can't shift by negative numbers in C/C++. :-(
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// Pawn moves
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if (us == WHITE)
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{
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// Pawn moves which give discovered check. This is possible only if the
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// pawn is not on the same file as the enemy king, because we don't
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// generate captures.
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n += generate_pawn_checks(WhitePawnOffsets, pos, dc, ksq, mlist);
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else
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n += generate_pawn_checks(BlackPawnOffsets, pos, dc, ksq, mlist);
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// Find all friendly pawns not on the enemy king's file
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b1 = pos.pawns(us) & ~file_bb(ksq);
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// Pieces moves
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Bitboard b = pos.knights(us);
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if (b)
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n += generate_piece_checks(KNIGHT, pos, b, dc, ksq, mlist);
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// Discovered checks, single pawn pushes
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b2 = b3 = ((b1 & dc) << 8) & ~Rank8BB & empty;
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while (b3)
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{
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to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - DELTA_N, to);
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}
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b = pos.bishops(us);
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if (b)
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n += generate_piece_checks(BISHOP, pos, b, dc, ksq, mlist);
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// Discovered checks, double pawn pushes
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b3 = ((b2 & Rank3BB) << 8) & empty;
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while (b3)
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{
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to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
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}
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b = pos.rooks(us);
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if (b)
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n += generate_piece_checks(ROOK, pos, b, dc, ksq, mlist);
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// Direct checks. These are possible only for pawns on neighboring files
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// of the enemy king
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b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
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// Direct checks, single pawn pushes
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b2 = (b1 << 8) & empty;
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b3 = b2 & pos.pawn_attacks(BLACK, ksq);
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while (b3)
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{
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to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - DELTA_N, to);
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}
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// Direct checks, double pawn pushes
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b3 = ((b2 & Rank3BB) << 8) & empty & pos.pawn_attacks(BLACK, ksq);
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while (b3)
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{
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to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
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}
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}
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else { // (us == BLACK)
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// Pawn moves which give discovered check. This is possible only if the
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// pawn is not on the same file as the enemy king, because we don't
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// generate captures.
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// Find all friendly pawns not on the enemy king's file:
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b1 = pos.pawns(us) & ~file_bb(ksq);
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// Discovered checks, single pawn pushes
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b2 = b3 = ((b1 & dc) >> 8) & ~Rank1BB & empty;
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while (b3)
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{
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to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - DELTA_S, to);
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}
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// Discovered checks, double pawn pushes
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b3 = ((b2 & Rank6BB) >> 8) & empty;
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while (b3)
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{
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to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
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}
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// Direct checks. These are possible only for pawns on neighboring files
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// of the enemy king
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b1 &= (~dc & neighboring_files_bb(ksq));
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// Direct checks, single pawn pushes:
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b2 = (b1 >> 8) & empty;
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b3 = b2 & pos.pawn_attacks(WHITE, ksq);
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while (b3)
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{
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to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - DELTA_S, to);
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}
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// Direct checks, double pawn pushes
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b3 = ((b2 & Rank6BB) >> 8) & empty & pos.pawn_attacks(WHITE, ksq);
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while (b3)
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{
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to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
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}
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}
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// Knight moves
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b1 = pos.knights(us);
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if (b1)
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n += generate_piece_checks(KNIGHT, pos, b1, dc, ksq, mlist);
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// Bishop moves
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b1 = pos.bishops(us);
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if (b1)
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n += generate_piece_checks(BISHOP, pos, b1, dc, ksq, mlist);
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// Rook moves
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b1 = pos.rooks(us);
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if (b1)
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n += generate_piece_checks(ROOK, pos, b1, dc, ksq, mlist);
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// Queen moves
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b1 = pos.queens(us);
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if (b1)
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n += generate_piece_checks(QUEEN, pos, b1, dc, ksq, mlist);
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b = pos.queens(us);
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if (b)
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n += generate_piece_checks(QUEEN, pos, b, dc, ksq, mlist);
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// King moves
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from = pos.king_square(us);
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Square from = pos.king_square(us);
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if (bit_is_set(dc, from))
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{
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b1 = pos.king_attacks(from) & empty & ~QueenPseudoAttacks[ksq];
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while (b1)
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b = pos.king_attacks(from) & pos.empty_squares() & ~QueenPseudoAttacks[ksq];
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while (b)
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{
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to = pop_1st_bit(&b1);
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Square to = pop_1st_bit(&b);
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mlist[n++].move = make_move(from, to);
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}
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}
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@ -1068,4 +984,55 @@ namespace {
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}
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return n;
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}
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int generate_pawn_checks(const PawnOffsets& ofs, const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist)
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{
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// Pawn moves which give discovered check. This is possible only if the
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// pawn is not on the same file as the enemy king, because we don't
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// generate captures.
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int n = 0;
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Bitboard empty = pos.empty_squares();
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// Find all friendly pawns not on the enemy king's file
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Bitboard b1 = pos.pawns(pos.side_to_move()) & ~file_bb(ksq), b2, b3;
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// Discovered checks, single pawn pushes
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b2 = b3 = (ofs.next_row_fn)(b1 & dc) & ~ofs.Rank8BB & empty;
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while (b3)
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{
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Square to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - ofs.DELTA_N, to);
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}
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// Discovered checks, double pawn pushes
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b3 = (ofs.next_row_fn)(b2 & ofs.Rank3BB) & empty;
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while (b3)
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{
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Square to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
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}
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// Direct checks. These are possible only for pawns on neighboring files
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// of the enemy king
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b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
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// Direct checks, single pawn pushes
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b2 = (ofs.next_row_fn)(b1) & empty;
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b3 = b2 & pos.pawn_attacks(ofs.them, ksq);
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while (b3)
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{
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Square to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - ofs.DELTA_N, to);
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}
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// Direct checks, double pawn pushes
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b3 = (ofs.next_row_fn)(b2 & ofs.Rank3BB) & empty & pos.pawn_attacks(ofs.them, ksq);
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while (b3)
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{
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Square to = pop_1st_bit(&b3);
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mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
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}
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return n;
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}
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}
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