// kbnk_mate_table() tries to drive toward corners A1 or H8,
// if we have a bishop that cannot reach the above squares we
- // mirror the kings so to drive enemy toward corners A8 or H1.
+ // flip the kings so to drive enemy toward corners A8 or H1.
if (opposite_colors(bishopSq, SQ_A1))
{
- winnerKSq = mirror(winnerKSq);
- loserKSq = mirror(loserKSq);
+ winnerKSq = ~winnerKSq;
+ loserKSq = ~loserKSq;
}
Value result = VALUE_KNOWN_WIN
return strongSide == pos.side_to_move() ? result : -result;
}
+// Returns a square that will allow us to orient the board so that
+// strongSide is white and strongSide's only pawn is on the left
+// half of the board
+Square get_flip_sq(const Position& pos, Color strongSide) {
+
+ assert(pos.count<PAWN>(strongSide) == 1);
+
+ Square psq = pos.list<PAWN>(strongSide)[0];
+
+ return (FILE_H * (file_of(psq) >= FILE_E)) | (RANK_8 * int(strongSide));
+}
+
+Square operator^(Square s, Square flip_sq) {
+ assert(flip_sq == SQ_A1 || flip_sq == SQ_H1 || flip_sq == SQ_A8 || flip_sq == SQ_H8);
+ return Square(int(s) ^ int(flip_sq));
+}
/// KP vs K. This endgame is evaluated with the help of a bitbase.
template<>
assert(verify_material(pos, strongSide, VALUE_ZERO, 1));
assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
- Square wksq = pos.king_square(strongSide);
- Square bksq = pos.king_square(weakSide);
- Square psq = pos.list<PAWN>(strongSide)[0];
- Color us = pos.side_to_move();
+ // Assume strongSide is white and the pawn is on files A-D
+ Square flip_sq = get_flip_sq(pos, strongSide);
- if (strongSide == BLACK)
- {
- wksq = ~wksq;
- bksq = ~bksq;
- psq = ~psq;
- us = ~us;
- }
+ Square wksq = pos.king_square(strongSide) ^ flip_sq;
+ Square bksq = pos.king_square(weakSide) ^ flip_sq;
+ Square psq = pos.list<PAWN>(strongSide)[0] ^ flip_sq;
- if (file_of(psq) >= FILE_E)
- {
- wksq = mirror(wksq);
- bksq = mirror(bksq);
- psq = mirror(psq);
- }
+ Color us = strongSide == pos.side_to_move() ? WHITE : BLACK;
if (!Bitbases::probe_kpk(wksq, psq, bksq, us))
return VALUE_DRAW;
assert(verify_material(pos, strongSide, RookValueMg, 0));
assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
- Square wksq = pos.king_square(strongSide);
- Square bksq = pos.king_square(weakSide);
- Square rsq = pos.list<ROOK>(strongSide)[0];
- Square psq = pos.list<PAWN>(weakSide)[0];
-
- if (strongSide == BLACK)
- {
- wksq = ~wksq;
- bksq = ~bksq;
- rsq = ~rsq;
- psq = ~psq;
- }
+ Square wksq = relative_square(strongSide, pos.king_square(strongSide));
+ Square bksq = relative_square(strongSide, pos.king_square(weakSide));
+ Square rsq = relative_square(strongSide, pos.list<ROOK>(strongSide)[0]);
+ Square psq = relative_square(strongSide, pos.list<PAWN>(weakSide)[0]);
Square queeningSq = file_of(psq) | RANK_1;
Value result;
assert(verify_material(pos, strongSide, RookValueMg, 1));
assert(verify_material(pos, weakSide, RookValueMg, 0));
- Square wksq = pos.king_square(strongSide);
- Square bksq = pos.king_square(weakSide);
- Square wrsq = pos.list<ROOK>(strongSide)[0];
- Square wpsq = pos.list<PAWN>(strongSide)[0];
- Square brsq = pos.list<ROOK>(weakSide)[0];
-
- // Orient the board in such a way that the stronger side is white, and the
- // pawn is on the left half of the board.
- if (strongSide == BLACK)
- {
- wksq = ~wksq;
- wrsq = ~wrsq;
- wpsq = ~wpsq;
- bksq = ~bksq;
- brsq = ~brsq;
- }
+ // Assume strongSide is white and the pawn is on files A-D
+ Square flip_sq = get_flip_sq(pos, strongSide);
- if (file_of(wpsq) > FILE_D)
- {
- wksq = mirror(wksq);
- wrsq = mirror(wrsq);
- wpsq = mirror(wpsq);
- bksq = mirror(bksq);
- brsq = mirror(brsq);
- }
+ Square wksq = pos.king_square(strongSide) ^ flip_sq;
+ Square bksq = pos.king_square(weakSide) ^ flip_sq;
+ Square wrsq = pos.list<ROOK>(strongSide)[0] ^ flip_sq;
+ Square wpsq = pos.list<PAWN>(strongSide)[0] ^ flip_sq;
+ Square brsq = pos.list<ROOK>(weakSide)[0] ^ flip_sq;
File f = file_of(wpsq);
Rank r = rank_of(wpsq);
assert(verify_material(pos, strongSide, KnightValueMg, 1));
assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
- Square pawnSq = pos.list<PAWN>(strongSide)[0];
- Square weakKingSq = pos.king_square(weakSide);
+ // Assume strongSide is white and the pawn is on files A-D
+ Square flip_sq = get_flip_sq(pos, strongSide);
- if ( pawnSq == relative_square(strongSide, SQ_A7)
- && square_distance(weakKingSq, relative_square(strongSide, SQ_A8)) <= 1)
- return SCALE_FACTOR_DRAW;
+ Square pawnSq = pos.list<PAWN>(strongSide)[0] ^ flip_sq;
+ Square weakKingSq = pos.king_square(weakSide) ^ flip_sq;
- if ( pawnSq == relative_square(strongSide, SQ_H7)
- && square_distance(weakKingSq, relative_square(strongSide, SQ_H8)) <= 1)
+ if (pawnSq == SQ_A7 && square_distance(SQ_A8, weakKingSq) <= 1)
return SCALE_FACTOR_DRAW;
return SCALE_FACTOR_NONE;
assert(verify_material(pos, strongSide, VALUE_ZERO, 1));
assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
- Square wksq = pos.king_square(strongSide);
- Square bksq = pos.king_square(weakSide);
- Square psq = pos.list<PAWN>(strongSide)[0];
- Color us = pos.side_to_move();
+ // Assume strongSide is white and the pawn is on files A-D
+ Square flip_sq = get_flip_sq(pos, strongSide);
- if (strongSide == BLACK)
- {
- wksq = ~wksq;
- bksq = ~bksq;
- psq = ~psq;
- us = ~us;
- }
+ Square wksq = pos.king_square(strongSide) ^ flip_sq;
+ Square bksq = pos.king_square(weakSide) ^ flip_sq;
+ Square psq = pos.list<PAWN>(strongSide)[0] ^ flip_sq;
- if (file_of(psq) >= FILE_E)
- {
- wksq = mirror(wksq);
- bksq = mirror(bksq);
- psq = mirror(psq);
- }
+ Color us = strongSide == pos.side_to_move() ? WHITE : BLACK;
// If the pawn has advanced to the fifth rank or further, and is not a
// rook pawn, it's too dangerous to assume that it's at least a draw.
projects / stockfish / blobdiff