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Pawn move generator: dispatch at compile time
Instead of function pointers use templates to dispatch shift operations. It is more clear and possibly also faster because branches are removed at compile time. Signed-off-by: Marco Costalba <mcostalba@gmail.com>
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Marco Costalba
parent
ad1bb084dd
commit
e2af0e775b
1 changed files with 110 additions and 120 deletions
230
src/movegen.cpp
230
src/movegen.cpp
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@ -32,29 +32,15 @@
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namespace {
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inline Bitboard forward_white(Bitboard b) { return b << 8; }
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inline Bitboard forward_right_white(Bitboard b) { return b << 9; }
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inline Bitboard forward_left_white(Bitboard b) { return b << 7; }
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inline Bitboard forward_black(Bitboard b) { return b >> 8; }
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inline Bitboard forward_right_black(Bitboard b) { return b >> 7; }
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inline Bitboard forward_left_black(Bitboard b) { return b >> 9; }
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struct PawnOffsets {
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Bitboard Rank3BB, Rank8BB;
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Rank RANK_8;
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SquareDelta DELTA_N, DELTA_NE, DELTA_NW;
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Color us, them;
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typedef Bitboard (*Shift_fn)(Bitboard b);
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Shift_fn forward, forward_left, forward_right;
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};
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const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, RANK_8, DELTA_N, DELTA_NE, DELTA_NW, WHITE, BLACK,
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&forward_white, forward_left_white, forward_right_white };
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const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, RANK_1, DELTA_S, DELTA_SE, DELTA_SW, BLACK, WHITE,
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&forward_black, &forward_left_black, &forward_right_black };
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const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, RANK_8, DELTA_N, DELTA_NE, DELTA_NW, WHITE, BLACK };
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const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, RANK_1, DELTA_S, DELTA_SE, DELTA_SW, BLACK, WHITE };
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int generate_castle_moves(const Position&, MoveStack*, Color);
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@ -648,7 +634,7 @@ namespace {
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int n = 0;
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// Captures in the a1-h8 (a8-h1 for black) direction
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Bitboard b1 = (ofs.forward_right)(pawns) & ~FileABB & enemyPieces;
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Bitboard b1 = (C == WHITE ? pawns << 9 : pawns >> 7) & ~FileABB & enemyPieces;
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// Capturing promotions
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Bitboard b2 = b1 & ofs.Rank8BB;
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@ -667,7 +653,7 @@ namespace {
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}
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// Captures in the h1-a8 (h8-a1 for black) direction
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b1 = (ofs.forward_left)(pawns) & ~FileHBB & enemyPieces;
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b1 = (C == WHITE ? pawns << 7 : pawns >> 9) & ~FileHBB & enemyPieces;
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// Capturing promotions
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b2 = b1 & ofs.Rank8BB;
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@ -686,7 +672,7 @@ namespace {
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}
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// Non-capturing promotions
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b1 = (ofs.forward)(pawns) & pos.empty_squares() & Rank8BB;
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b1 = (C == WHITE ? pawns << 8 : pawns >> 8) & pos.empty_squares() & Rank8BB;
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while (b1)
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{
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sq = pop_1st_bit(&b1);
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@ -725,7 +711,7 @@ namespace {
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int n = 0;
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// Underpromotion captures in the a1-h8 (a8-h1 for black) direction
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b1 = ofs.forward_right(pawns) & ~FileABB & enemyPieces & ofs.Rank8BB;
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b1 = (C == WHITE ? pawns << 9 : pawns >> 7) & ~FileABB & enemyPieces & ofs.Rank8BB;
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while (b1)
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{
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sq = pop_1st_bit(&b1);
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@ -735,7 +721,7 @@ namespace {
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}
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// Underpromotion captures in the h1-a8 (h8-a1 for black) direction
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b1 = ofs.forward_left(pawns) & ~FileHBB & enemyPieces & ofs.Rank8BB;
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b1 = (C == WHITE ? pawns << 7 : pawns >> 9) & ~FileHBB & enemyPieces & ofs.Rank8BB;
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while (b1)
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{
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sq = pop_1st_bit(&b1);
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@ -745,7 +731,7 @@ namespace {
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}
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// Single pawn pushes
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b1 = ofs.forward(pawns) & emptySquares;
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b1 = (C == WHITE ? pawns << 8 : pawns >> 8) & emptySquares;
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b2 = b1 & ofs.Rank8BB;
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while (b2)
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{
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@ -762,7 +748,7 @@ namespace {
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}
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// Double pawn pushes
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b2 = (ofs.forward(b1 & ofs.Rank3BB)) & emptySquares;
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b2 = (C == WHITE ? (b1 & ofs.Rank3BB) << 8 : (b1 & ofs.Rank3BB) >> 8) & emptySquares;
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while (b2)
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{
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sq = pop_1st_bit(&b2);
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@ -772,6 +758,107 @@ namespace {
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}
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template<Color C>
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int generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist, int n)
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{
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static const PawnOffsets ofs = (C == WHITE ? WhitePawnOffsets : BlackPawnOffsets);
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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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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 = (C == WHITE ? (b1 & dc) << 8 : (b1 & dc) >> 8) & ~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 = (C == WHITE ? (b2 & ofs.Rank3BB) << 8 : (b2 & ofs.Rank3BB) >> 8) & 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 = (C == WHITE ? b1 << 8 : b1 >> 8) & 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 = (C == WHITE ? (b2 & ofs.Rank3BB) << 8 : (b2 & ofs.Rank3BB) >> 8)
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& empty
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& 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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template<Color C>
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int generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned,
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Bitboard blockSquares, MoveStack* mlist, int n) {
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static const PawnOffsets ofs = (C == WHITE ? WhitePawnOffsets : BlackPawnOffsets);
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// Find non-pinned pawns
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Bitboard b1 = pos.pawns(ofs.us) & not_pinned;
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// Single pawn pushes. We don't have to AND with empty squares here,
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// because the blocking squares will always be empty.
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Bitboard b2 = (C == WHITE ? b1 << 8 : b1 >> 8) & blockSquares;
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while (b2)
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{
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Square to = pop_1st_bit(&b2);
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assert(pos.piece_on(to) == EMPTY);
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if (square_rank(to) == ofs.RANK_8)
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{
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mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, QUEEN);
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mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, ROOK);
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mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, BISHOP);
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mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, KNIGHT);
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} else
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mlist[n++].move = make_move(to - ofs.DELTA_N, to);
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}
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// Double pawn pushes
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b2 = (C == WHITE ? b1 << 8 : b1 >> 8) & pos.empty_squares() & ofs.Rank3BB;
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b2 = (C == WHITE ? b2 << 8 : b2 >> 8) & blockSquares;;
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while (b2)
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{
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Square to = pop_1st_bit(&b2);
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assert(pos.piece_on(to) == EMPTY);
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assert(ofs.us != WHITE || square_rank(to) == RANK_4);
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assert(ofs.us != BLACK || square_rank(to) == RANK_5);
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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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int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) {
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int n = 0;
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@ -836,101 +923,4 @@ namespace {
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}
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return n;
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}
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template<Color C>
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int generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist, int n)
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{
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static const PawnOffsets ofs = (C == WHITE ? WhitePawnOffsets : BlackPawnOffsets);
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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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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.forward)(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.forward)(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.forward)(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.forward)(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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template<Color C>
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int generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned,
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Bitboard blockSquares, MoveStack* mlist, int n) {
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static const PawnOffsets ofs = (C == WHITE ? WhitePawnOffsets : BlackPawnOffsets);
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// Find non-pinned pawns
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Bitboard b1 = pos.pawns(ofs.us) & not_pinned;
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// Single pawn pushes. We don't have to AND with empty squares here,
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// because the blocking squares will always be empty.
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Bitboard b2 = (ofs.forward)(b1) & blockSquares;
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while (b2)
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{
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Square to = pop_1st_bit(&b2);
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assert(pos.piece_on(to) == EMPTY);
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if (square_rank(to) == ofs.RANK_8)
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{
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mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, QUEEN);
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mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, ROOK);
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mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, BISHOP);
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mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, KNIGHT);
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} else
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mlist[n++].move = make_move(to - ofs.DELTA_N, to);
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}
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// Double pawn pushes
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b2 = (ofs.forward)((ofs.forward)(b1) & pos.empty_squares() & ofs.Rank3BB) & blockSquares;
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while (b2)
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{
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Square to = pop_1st_bit(&b2);
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assert(pos.piece_on(to) == EMPTY);
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assert(ofs.us != WHITE || square_rank(to) == RANK_4);
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assert(ofs.us != BLACK || square_rank(to) == RANK_5);
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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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