/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2016 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2020 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
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
- // There are 24 possible pawn squares: the first 4 files and ranks from 2 to 7
- const unsigned MAX_INDEX = 2*24*64*64; // stm * psq * wksq * bksq = 196608
+ // There are 24 possible pawn squares: files A to D and ranks from 2 to 7.
+ // 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];
// Each uint32_t stores results of 32 positions, one per bit
uint32_t KPKBitbase[MAX_INDEX / 32];
// bit 13-14: white pawn file (from FILE_A to FILE_D)
// bit 15-17: white pawn RANK_7 - rank (from RANK_7 - RANK_7 to RANK_7 - RANK_2)
unsigned index(Color us, Square bksq, Square wksq, Square psq) {
// bit 13-14: white pawn file (from FILE_A to FILE_D)
// bit 15-17: white pawn RANK_7 - rank (from RANK_7 - RANK_7 to RANK_7 - RANK_2)
unsigned index(Color us, Square bksq, Square wksq, Square psq) {
ksq[WHITE] = Square((idx >> 0) & 0x3F);
ksq[BLACK] = Square((idx >> 6) & 0x3F);
us = Color ((idx >> 12) & 0x01);
ksq[WHITE] = Square((idx >> 0) & 0x3F);
ksq[BLACK] = Square((idx >> 6) & 0x3F);
us = Color ((idx >> 12) & 0x01);
// Check 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
// Check 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
- && 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
+ || (PseudoAttacks[KING][ksq[us]] & (psq + NORTH))))
- && ( !(StepAttacksBB[KING][ksq[us]] & ~(StepAttacksBB[KING][ksq[~us]] | StepAttacksBB[PAWN][psq]))
- || (StepAttacksBB[KING][ksq[us]] & psq & ~StepAttacksBB[KING][ksq[~us]])))
+ && ( !(PseudoAttacks[KING][ksq[us]] & ~(PseudoAttacks[KING][ksq[~us]] | PawnAttacks[~us][psq]))
+ || (PseudoAttacks[KING][ksq[us]] & psq & ~PseudoAttacks[KING][ksq[~us]])))
// as WIN, the position is classified as WIN, otherwise the current position is
// classified as UNKNOWN.
// 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);
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Result Good = (Us == WHITE ? WIN : DRAW);
+ constexpr Result Bad = (Us == WHITE ? DRAW : WIN);
while (b)
r |= Us == WHITE ? db[index(Them, ksq[Them] , pop_lsb(&b), psq)]
while (b)
r |= Us == WHITE ? db[index(Them, ksq[Them] , pop_lsb(&b), psq)]
- r |= db[index(Them, ksq[Them], ksq[Us], psq + DELTA_N)];
+ r |= db[index(Them, ksq[Them], ksq[Us], psq + NORTH)];
- && 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)];