X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=70114f20fadd3485e2c30d93f2760038ea50c61d;hp=4e2778a946b89a282d83ba51f774d8b21fe2ecee;hb=baf184e8d9e22c86407538ab4b4004f58e0e996d;hpb=8a4821923ac6860c791185a6d25c60ad0391739f diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 4e2778a9..70114f20 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -2,7 +2,7 @@ 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) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, 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 @@ -19,24 +19,16 @@ */ #include +#include #include "bitboard.h" #include "misc.h" uint8_t PopCnt16[1 << 16]; -int SquareDistance[SQUARE_NB][SQUARE_NB]; +uint8_t SquareDistance[SQUARE_NB][SQUARE_NB]; Bitboard SquareBB[SQUARE_NB]; -Bitboard FileBB[FILE_NB]; -Bitboard RankBB[RANK_NB]; -Bitboard AdjacentFilesBB[FILE_NB]; -Bitboard ForwardRanksBB[COLOR_NB][RANK_NB]; -Bitboard BetweenBB[SQUARE_NB][SQUARE_NB]; Bitboard LineBB[SQUARE_NB][SQUARE_NB]; -Bitboard DistanceRingBB[SQUARE_NB][8]; -Bitboard ForwardFileBB[COLOR_NB][SQUARE_NB]; -Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB]; -Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB]; Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB]; Bitboard PawnAttacks[COLOR_NB][SQUARE_NB]; @@ -49,15 +41,6 @@ namespace { Bitboard BishopTable[0x1480]; // To store bishop attacks void init_magics(Bitboard table[], Magic magics[], Direction directions[]); - - // popcount16() counts the non-zero bits using SWAR-Popcount algorithm - - unsigned popcount16(unsigned u) { - u -= (u >> 1) & 0x5555U; - u = ((u >> 2) & 0x3333U) + (u & 0x3333U); - u = ((u >> 4) + u) & 0x0F0FU; - return (u * 0x0101U) >> 8; - } } @@ -86,56 +69,36 @@ const std::string Bitboards::pretty(Bitboard b) { void Bitboards::init() { for (unsigned i = 0; i < (1 << 16); ++i) - PopCnt16[i] = (uint8_t) popcount16(i); + PopCnt16[i] = std::bitset<16>(i).count(); for (Square s = SQ_A1; s <= SQ_H8; ++s) SquareBB[s] = (1ULL << s); - for (File f = FILE_A; f <= FILE_H; ++f) - FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB; - - for (Rank r = RANK_1; r <= RANK_8; ++r) - RankBB[r] = r > RANK_1 ? RankBB[r - 1] << 8 : Rank1BB; + for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) + for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) + SquareDistance[s1][s2] = std::max(distance(s1, s2), distance(s1, s2)); - for (File f = FILE_A; f <= FILE_H; ++f) - AdjacentFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0); + for (Square s = SQ_A1; s <= SQ_H8; ++s) + { + PawnAttacks[WHITE][s] = pawn_attacks_bb(square_bb(s)); + PawnAttacks[BLACK][s] = pawn_attacks_bb(square_bb(s)); + } - for (Rank r = RANK_1; r < RANK_8; ++r) - ForwardRanksBB[WHITE][r] = ~(ForwardRanksBB[BLACK][r + 1] = ForwardRanksBB[BLACK][r] | RankBB[r]); + // Helper returning the target bitboard of a step from a square + auto landing_square_bb = [&](Square s, int step) + { + Square to = Square(s + step); + return is_ok(to) && distance(s, to) <= 2 ? square_bb(to) : Bitboard(0); + }; - for (Color c = WHITE; c <= BLACK; ++c) - for (Square s = SQ_A1; s <= SQ_H8; ++s) - { - ForwardFileBB [c][s] = ForwardRanksBB[c][rank_of(s)] & FileBB[file_of(s)]; - PawnAttackSpan[c][s] = ForwardRanksBB[c][rank_of(s)] & AdjacentFilesBB[file_of(s)]; - PassedPawnMask[c][s] = ForwardFileBB [c][s] | PawnAttackSpan[c][s]; - } + for (Square s = SQ_A1; s <= SQ_H8; ++s) + { + for (int step : {-9, -8, -7, -1, 1, 7, 8, 9} ) + PseudoAttacks[KING][s] |= landing_square_bb(s, step); - for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) - for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) - if (s1 != s2) - { - SquareDistance[s1][s2] = std::max(distance(s1, s2), distance(s1, s2)); - DistanceRingBB[s1][SquareDistance[s1][s2]] |= s2; - } - - int steps[][5] = { {}, { 7, 9 }, { 6, 10, 15, 17 }, {}, {}, {}, { 1, 7, 8, 9 } }; - - for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt : { PAWN, KNIGHT, KING }) - for (Square s = SQ_A1; s <= SQ_H8; ++s) - for (int i = 0; steps[pt][i]; ++i) - { - Square to = s + Direction(c == WHITE ? steps[pt][i] : -steps[pt][i]); - - if (is_ok(to) && distance(s, to) < 3) - { - if (pt == PAWN) - PawnAttacks[c][s] |= to; - else - PseudoAttacks[pt][s] |= to; - } - } + for (int step : {-17, -15, -10, -6, 6, 10, 15, 17} ) + PseudoAttacks[KNIGHT][s] |= landing_square_bb(s, step); + } Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST }; Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; @@ -150,13 +113,8 @@ void Bitboards::init() { for (PieceType pt : { BISHOP, ROOK }) for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) - { - if (!(PseudoAttacks[pt][s1] & s2)) - continue; - - LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2; - BetweenBB[s1][s2] = attacks_bb(pt, s1, SquareBB[s2]) & attacks_bb(pt, s2, SquareBB[s1]); - } + if (PseudoAttacks[pt][s1] & s2) + LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2; } } @@ -184,8 +142,8 @@ namespace { // init_magics() computes all rook and bishop attacks at startup. Magic // bitboards are used to look up attacks of sliding pieces. As a reference see - // chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we - // use the so called "fancy" approach. + // www.chessprogramming.org/Magic_Bitboards. In particular, here we use the so + // called "fancy" approach. void init_magics(Bitboard table[], Magic magics[], Direction directions[]) {