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Use flip_sq idea in endgame.cpp

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The normalising transformation is computed all at
once by the helper function get_flip_sq and then
applied immediately to the relevant squares as soon
as they are loaded from the position class.

bench: 8350690
This commit is contained in:
Chris Caino 2013-10-22 23:03:45 +01:00 • committed by Marco Costalba
parent 72f7282ad4
commit 3674f18b97
1 changed files with 47 additions and 80 deletions
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127
src/endgame.cpp
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@ -174,11 +174,11 @@ Value Endgame<KBNK>::operator()(const Position& pos) const {
// 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
@ -188,6 +188,22 @@ Value Endgame<KBNK>::operator()(const Position& pos) const {
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<>
@ -196,25 +212,14 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
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;
@ -235,18 +240,10 @@ Value Endgame<KRKP>::operator()(const Position& pos) const {
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;
@ -486,31 +483,14 @@ ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
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];
// Assume strongSide is white and the pawn is on files A-D
Square flip_sq = get_flip_sq(pos, strongSide);
// 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;
}
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);
@ -852,15 +832,13 @@ ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
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;
@ -896,25 +874,14 @@ ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
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.