along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#include <algorithm>
#include <cassert>
-#include <numeric>
#include <vector>
#include "bitboard.h"
inline Result& operator|=(Result& r, Result v) { return r = Result(r | v); }
struct KPKPosition {
- KPKPosition() = default;
+
KPKPosition(unsigned idx);
operator Result() const { return result; }
Result classify(const std::vector<KPKPosition>& db)
{ return us == WHITE ? classify<WHITE>(db) : classify<BLACK>(db); }
+ private:
template<Color Us> Result classify(const std::vector<KPKPosition>& db);
- unsigned id;
Color us;
Square bksq, wksq, psq;
Result result;
void Bitbases::init() {
- std::vector<KPKPosition> db(MAX_INDEX);
+ unsigned idx, repeat = 1;
+ std::vector<KPKPosition> db;
+ db.reserve(MAX_INDEX);
// Initialize db with known win / draw positions
- std::generate(db.begin(), db.end(), [](){ static unsigned id; return KPKPosition(id++); });
+ for (idx = 0; idx < MAX_INDEX; ++idx)
+ db.push_back(KPKPosition(idx));
// Iterate through the positions until none of the unknown positions can be
// changed to either wins or draws (15 cycles needed).
- while (std::accumulate(db.begin(), db.end(), false, [&](bool repeat, KPKPosition& pos)
- { return (pos == UNKNOWN && pos.classify(db) != UNKNOWN) || repeat; }));
+ while (repeat)
+ for (repeat = idx = 0; idx < MAX_INDEX; ++idx)
+ repeat |= (db[idx] == UNKNOWN && db[idx].classify(db) != UNKNOWN);
// Map 32 results into one KPKBitbase[] entry
- for (auto& pos : db)
- if (pos == WIN)
- KPKBitbase[pos.id / 32] |= 1 << (pos.id & 0x1F);
+ for (idx = 0; idx < MAX_INDEX; ++idx)
+ if (db[idx] == WIN)
+ KPKBitbase[idx / 32] |= 1 << (idx & 0x1F);
}
KPKPosition::KPKPosition(unsigned idx) {
- id = idx;
wksq = Square((idx >> 0) & 0x3F);
bksq = Square((idx >> 6) & 0x3F);
us = Color ((idx >> 12) & 0x01);
// as WIN, the position is classified as WIN, otherwise the current position is
// classified as UNKNOWN.
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Result Good = (Us == WHITE ? WIN : DRAW);
- const Result Bad = (Us == WHITE ? DRAW : WIN);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
Result r = INVALID;
Bitboard b = StepAttacksBB[KING][Us == WHITE ? wksq : bksq];
r |= db[index(BLACK, bksq, wksq, s + DELTA_N)]; // Double push
}
- return result = r & Good ? Good : r & UNKNOWN ? UNKNOWN : Bad;
+ if (Us == WHITE)
+ return result = r & WIN ? WIN : r & UNKNOWN ? UNKNOWN : DRAW;
+ else
+ return result = r & DRAW ? DRAW : r & UNKNOWN ? UNKNOWN : WIN;
}
} // namespace