/*
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) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
*/
#include <cassert>
-#include <numeric>
#include <vector>
+#include <bitset>
#include "bitboard.h"
#include "types.h"
// Positions with the pawn on files E to H will be mirrored before probing.
constexpr unsigned MAX_INDEX = 2*24*64*64; // stm * psq * wksq * bksq = 196608
- // Each uint32_t stores results of 32 positions, one per bit
- uint32_t KPKBitbase[MAX_INDEX / 32];
+ std::bitset<MAX_INDEX> KPKBitbase;
// A KPK bitbase index is an integer in [0, IndexMax] range
//
assert(file_of(wpsq) <= FILE_D);
- unsigned idx = index(stm, bksq, wksq, wpsq);
- return KPKBitbase[idx / 32] & (1 << (idx & 0x1F));
+ return KPKBitbase[index(stm, bksq, wksq, wpsq)];
}
for (repeat = idx = 0; idx < MAX_INDEX; ++idx)
repeat |= (db[idx] == UNKNOWN && db[idx].classify(db) != UNKNOWN);
- // Map 32 results into one KPKBitbase[] entry
+ // Fill the bitbase with the decisive results
for (idx = 0; idx < MAX_INDEX; ++idx)
if (db[idx] == WIN)
- KPKBitbase[idx / 32] |= 1 << (idx & 0x1F);
+ KPKBitbase.set(idx);
}
stm = Color ((idx >> 12) & 0x01);
psq = make_square(File((idx >> 13) & 0x3), Rank(RANK_7 - ((idx >> 15) & 0x7)));
- // Check if two pieces are on the same square or if a king can be captured
+ // Invalid if two pieces are on the same square or if a king can be captured
if ( distance(ksq[WHITE], ksq[BLACK]) <= 1
|| ksq[WHITE] == psq
|| ksq[BLACK] == psq
- || (stm == WHITE && (PawnAttacks[WHITE][psq] & ksq[BLACK])))
+ || (stm == WHITE && (pawn_attacks_bb(WHITE, psq) & ksq[BLACK])))
result = INVALID;
- // Immediate win if a pawn can be promoted without getting captured
+ // Win if the pawn can be promoted without getting captured
else if ( stm == WHITE
&& rank_of(psq) == RANK_7
- && ksq[stm] != psq + NORTH
- && ( distance(ksq[~stm], psq + NORTH) > 1
- || (PseudoAttacks[KING][ksq[stm]] & (psq + NORTH))))
+ && ksq[WHITE] != psq + NORTH
+ && ( distance(ksq[BLACK], psq + NORTH) > 1
+ || (distance(ksq[WHITE], psq + NORTH) == 1)))
result = WIN;
- // Immediate draw if it is a stalemate or a king captures undefended pawn
+ // Draw if it is stalemate or the black king can capture the pawn
else if ( stm == BLACK
- && ( !(PseudoAttacks[KING][ksq[stm]] & ~(PseudoAttacks[KING][ksq[~stm]] | PawnAttacks[~stm][psq]))
- || (PseudoAttacks[KING][ksq[stm]] & psq & ~PseudoAttacks[KING][ksq[~stm]])))
+ && ( !(attacks_bb<KING>(ksq[BLACK]) & ~(attacks_bb<KING>(ksq[WHITE]) | pawn_attacks_bb(WHITE, psq)))
+ || (attacks_bb<KING>(ksq[BLACK]) & ~attacks_bb<KING>(ksq[WHITE]) & psq)))
result = DRAW;
// Position will be classified later
const Result Bad = (stm == WHITE ? DRAW : WIN);
Result r = INVALID;
- Bitboard b = PseudoAttacks[KING][ksq[stm]];
+ Bitboard b = attacks_bb<KING>(ksq[stm]);
while (b)
r |= stm == WHITE ? db[index(BLACK, ksq[BLACK] , pop_lsb(&b), psq)]