Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
WIN = 4
};
- inline Result& operator|=(Result& r, Result v) { return r = Result(r | v); }
+ Result& operator|=(Result& r, Result v) { return r = Result(r | v); }
struct KPKPosition {
KPKPosition() = default;
template<Color Us> Result classify(const std::vector<KPKPosition>& db);
- unsigned id;
Color us;
Square ksq[COLOR_NB], psq;
Result result;
void Bitbases::init() {
std::vector<KPKPosition> db(MAX_INDEX);
+ unsigned idx, repeat = 1;
// 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[idx] = 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;
ksq[WHITE] = Square((idx >> 0) & 0x3F);
ksq[BLACK] = Square((idx >> 6) & 0x3F);
us = Color ((idx >> 12) & 0x01);
// Immediate win if a pawn can be promoted without getting captured
else if ( us == WHITE
&& rank_of(psq) == RANK_7
- && ksq[us] != psq + DELTA_N
- && ( distance(ksq[~us], psq + DELTA_N) > 1
- || (StepAttacksBB[KING][ksq[us]] & (psq + DELTA_N))))
+ && ksq[us] != psq + NORTH
+ && ( distance(ksq[~us], psq + NORTH) > 1
+ || (StepAttacksBB[KING][ksq[us]] & (psq + NORTH))))
result = WIN;
// Immediate draw if it is a stalemate or a king captures undefended pawn
if (Us == WHITE)
{
if (rank_of(psq) < RANK_7) // Single push
- r |= db[index(Them, ksq[Them], ksq[Us], psq + DELTA_N)];
+ r |= db[index(Them, ksq[Them], ksq[Us], psq + NORTH)];
if ( rank_of(psq) == RANK_2 // Double push
- && psq + DELTA_N != ksq[Us]
- && psq + DELTA_N != ksq[Them])
- r |= db[index(Them, ksq[Them], ksq[Us], psq + DELTA_N + DELTA_N)];
+ && psq + NORTH != ksq[Us]
+ && psq + NORTH != ksq[Them])
+ r |= db[index(Them, ksq[Them], ksq[Us], psq + NORTH + NORTH)];
}
return result = r & Good ? Good : r & UNKNOWN ? UNKNOWN : Bad;