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Further speed up bitbase generation

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Another trick, along the same lines of previous
patch. This time we first check positions with
white side to move that, becuase we start with
pawn on rank 7, are easily classified as wins,
then black ones.

Number of cycles reduced to 15 !

Becuase now it is faster we can remove a lot of
code to detect theoretical draws. We will calculate
them anyhow, although a bit slower, but the speed
up trick more than compensates it.

Verified that generated bitbases match original ones.

No functional change.
This commit is contained in:
Marco Costalba
2013-02-15 08:56:04 +01:00
parent 10d29add18
commit e0dfb0bc34
3 changed files with 61 additions and 106 deletions
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14
src/endgame.cpp
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@@ -199,21 +199,21 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
assert(pos.piece_count(weakerSide, PAWN) == 0);
Square wksq, bksq, wpsq;
Color stm;
Color us;
if (strongerSide == WHITE)
{
wksq = pos.king_square(WHITE);
bksq = pos.king_square(BLACK);
wpsq = pos.piece_list(WHITE, PAWN)[0];
stm = pos.side_to_move();
us = pos.side_to_move();
}
else
{
wksq = ~pos.king_square(BLACK);
bksq = ~pos.king_square(WHITE);
wpsq = ~pos.piece_list(BLACK, PAWN)[0];
stm = ~pos.side_to_move();
us = ~pos.side_to_move();
}
if (file_of(wpsq) >= FILE_E)
@@ -223,7 +223,7 @@ Value Endgame<KPK>::operator()(const Position& pos) const {
wpsq = mirror(wpsq);
}
if (!Bitbases::probe_kpk(wksq, wpsq, bksq, stm))
if (!Bitbases::probe_kpk(wksq, wpsq, bksq, us))
return VALUE_DRAW;
Value result = VALUE_KNOWN_WIN + PawnValueEg + Value(rank_of(wpsq));
@@ -920,14 +920,14 @@ ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
Square wksq = pos.king_square(strongerSide);
Square bksq = pos.king_square(weakerSide);
Square wpsq = pos.piece_list(strongerSide, PAWN)[0];
Color stm = pos.side_to_move();
Color us = pos.side_to_move();
if (strongerSide == BLACK)
{
wksq = ~wksq;
bksq = ~bksq;
wpsq = ~wpsq;
stm = ~stm;
us = ~us;
}
if (file_of(wpsq) >= FILE_E)
@@ -945,5 +945,5 @@ ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
// Probe the KPK bitbase with the weakest side's pawn removed. If it's a draw,
// it's probably at least a draw even with the pawn.
return Bitbases::probe_kpk(wksq, wpsq, bksq, stm) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
return Bitbases::probe_kpk(wksq, wpsq, bksq, us) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
}