X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=21cd34a2997812998b828901cbb575f0007afb4d;hp=794f54cf68326cf92fec7ff172a1f1959eaa62d2;hb=dfd030b67af4e651a73232ab15182fe669909ef1;hpb=5c5af4fa6533e22fb56dd22985cf2b3938efde6c diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 794f54cf..21cd34a2 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, 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 @@ -38,11 +38,10 @@ int BShifts[64]; Bitboard SetMaskBB[65]; Bitboard ClearMaskBB[65]; -Bitboard SquaresByColorBB[2]; Bitboard FileBB[8]; Bitboard RankBB[8]; -Bitboard NeighboringFilesBB[8]; -Bitboard ThisAndNeighboringFilesBB[8]; +Bitboard AdjacentFilesBB[8]; +Bitboard ThisAndAdjacentFilesBB[8]; Bitboard InFrontBB[2][8]; Bitboard StepAttacksBB[16][64]; Bitboard BetweenBB[64][64]; @@ -50,9 +49,7 @@ Bitboard SquaresInFrontMask[2][64]; Bitboard PassedPawnMask[2][64]; Bitboard AttackSpanMask[2][64]; -Bitboard BishopPseudoAttacks[64]; -Bitboard RookPseudoAttacks[64]; -Bitboard QueenPseudoAttacks[64]; +Bitboard PseudoAttacks[6][64]; uint8_t BitCount8Bit[256]; int SquareDistance[64][64]; @@ -62,11 +59,13 @@ namespace { CACHE_LINE_ALIGNMENT int BSFTable[64]; - Bitboard RookTable[0x19000]; // Storage space for rook attacks - Bitboard BishopTable[0x1480]; // Storage space for bishop attacks + Bitboard RTable[0x19000]; // Storage space for rook attacks + Bitboard BTable[0x1480]; // Storage space for bishop attacks - void init_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], int shifts[]); + typedef unsigned (Fn)(Square, Bitboard); + + void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], + Bitboard masks[], int shifts[], Square deltas[], Fn get_index); } @@ -155,10 +154,7 @@ Square pop_1st_bit(Bitboard* bb) { void bitboards_init() { for (Bitboard b = 0; b < 256; b++) - BitCount8Bit[b] = (uint8_t)count_1s(b); - - SquaresByColorBB[DARK] = 0xAA55AA55AA55AA55ULL; - SquaresByColorBB[LIGHT] = ~SquaresByColorBB[DARK]; + BitCount8Bit[b] = (uint8_t)popcount(b); for (Square s = SQ_A1; s <= SQ_H8; s++) { @@ -166,7 +162,7 @@ void bitboards_init() { ClearMaskBB[s] = ~SetMaskBB[s]; } - ClearMaskBB[SQ_NONE] = ~EmptyBoardBB; + ClearMaskBB[SQ_NONE] = ~0ULL; FileBB[FILE_A] = FileABB; RankBB[RANK_1] = Rank1BB; @@ -179,8 +175,8 @@ void bitboards_init() { for (int f = FILE_A; f <= FILE_H; f++) { - NeighboringFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0); - ThisAndNeighboringFilesBB[f] = FileBB[f] | NeighboringFilesBB[f]; + AdjacentFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0); + ThisAndAdjacentFilesBB[f] = FileBB[f] | AdjacentFilesBB[f]; } for (int rw = RANK_7, rb = RANK_2; rw >= RANK_1; rw--, rb++) @@ -193,8 +189,8 @@ void bitboards_init() { for (Square s = SQ_A1; s <= SQ_H8; s++) { SquaresInFrontMask[c][s] = in_front_bb(c, s) & file_bb(s); - PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(file_of(s)); - AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(file_of(s)); + PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_adjacent_files_bb(file_of(s)); + AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(file_of(s)); } for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++) @@ -202,12 +198,12 @@ void bitboards_init() { SquareDistance[s1][s2] = std::max(file_distance(s1, s2), rank_distance(s1, s2)); for (int i = 0; i < 64; i++) - if (!CpuIs64Bit) // Matt Taylor's folding trick for 32 bit systems + if (!Is64Bit) // Matt Taylor's folding trick for 32 bit systems { Bitboard b = 1ULL << i; b ^= b - 1; b ^= b >> 32; - BSFTable[uint32_t(b * 0x783A9B23) >> 26] = i; + BSFTable[(uint32_t)(b * 0x783A9B23) >> 26] = i; } else BSFTable[((1ULL << i) * 0x218A392CD3D5DBFULL) >> 58] = i; @@ -226,19 +222,22 @@ void bitboards_init() { set_bit(&StepAttacksBB[make_piece(c, pt)][s], to); } - init_magic_bitboards(ROOK, RAttacks, RMagics, RMasks, RShifts); - init_magic_bitboards(BISHOP, BAttacks, BMagics, BMasks, BShifts); + Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W }; + Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW }; + + init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, r_index); + init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, b_index); for (Square s = SQ_A1; s <= SQ_H8; s++) { - BishopPseudoAttacks[s] = bishop_attacks_bb(s, EmptyBoardBB); - RookPseudoAttacks[s] = rook_attacks_bb(s, EmptyBoardBB); - QueenPseudoAttacks[s] = queen_attacks_bb(s, EmptyBoardBB); + PseudoAttacks[BISHOP][s] = bishop_attacks_bb(s, 0); + PseudoAttacks[ROOK][s] = rook_attacks_bb(s, 0); + PseudoAttacks[QUEEN][s] = PseudoAttacks[BISHOP][s] | PseudoAttacks[ROOK][s]; } for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++) for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++) - if (bit_is_set(QueenPseudoAttacks[s1], s2)) + if (bit_is_set(PseudoAttacks[QUEEN][s1], s2)) { Square delta = (s2 - s1) / square_distance(s1, s2); @@ -250,28 +249,22 @@ void bitboards_init() { namespace { - Bitboard sliding_attacks(PieceType pt, Square sq, Bitboard occupied) { + Bitboard sliding_attack(Square deltas[], Square sq, Bitboard occupied) { - Square deltas[][4] = { { DELTA_N, DELTA_E, DELTA_S, DELTA_W }, - { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW } }; - Bitboard attacks = 0; - Square* delta = (pt == ROOK ? deltas[0] : deltas[1]); + Bitboard attack = 0; for (int i = 0; i < 4; i++) - { - Square s = sq + delta[i]; - - while (square_is_ok(s) && square_distance(s, s - delta[i]) == 1) + for (Square s = sq + deltas[i]; + square_is_ok(s) && square_distance(s, s - deltas[i]) == 1; + s += deltas[i]) { - set_bit(&attacks, s); + set_bit(&attack, s); if (bit_is_set(occupied, s)) break; - - s += delta[i]; } - } - return attacks; + + return attack; } @@ -297,22 +290,22 @@ namespace { } - // init_magic_bitboards() computes all rook and bishop magics at startup. - // Magic bitboards are used to look up attacks of sliding pieces. As reference - // see chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we + // 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. - void init_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], int shifts[]) { + void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], + Bitboard masks[], int shifts[], Square deltas[], Fn get_index) { int MagicBoosters[][8] = { { 3191, 2184, 1310, 3618, 2091, 1308, 2452, 3996 }, { 1059, 3608, 605, 3234, 3326, 38, 2029, 3043 } }; RKISS rk; Bitboard occupancy[4096], reference[4096], edges, b; - int i, size, index, booster; + int i, size, booster; // attacks[s] is a pointer to the beginning of the attacks table for square 's' - attacks[SQ_A1] = (pt == ROOK ? RookTable : BishopTable); + attacks[SQ_A1] = table; for (Square s = SQ_A1; s <= SQ_H8; s++) { @@ -324,15 +317,15 @@ namespace { // all the attacks for each possible subset of the mask and so is 2 power // the number of 1s of the mask. Hence we deduce the size of the shift to // apply to the 64 or 32 bits word to get the index. - masks[s] = sliding_attacks(pt, s, EmptyBoardBB) & ~edges; - shifts[s] = (CpuIs64Bit ? 64 : 32) - count_1s(masks[s]); + masks[s] = sliding_attack(deltas, s, 0) & ~edges; + shifts[s] = (Is64Bit ? 64 : 32) - popcount(masks[s]); // Use Carry-Rippler trick to enumerate all subsets of masks[s] and - // store the corresponding sliding attacks bitboard in reference[]. + // store the corresponding sliding attack bitboard in reference[]. b = size = 0; do { occupancy[size] = b; - reference[size++] = sliding_attacks(pt, s, b); + reference[size++] = sliding_attack(deltas, s, b); b = (b - masks[s]) & masks[s]; } while (b); @@ -341,7 +334,7 @@ namespace { if (s < SQ_H8) attacks[s + 1] = attacks[s] + size; - booster = MagicBoosters[CpuIs64Bit][rank_of(s)]; + booster = MagicBoosters[Is64Bit][rank_of(s)]; // Find a magic for square 's' picking up an (almost) random number // until we find the one that passes the verification test. @@ -355,14 +348,12 @@ namespace { // effect of verifying the magic. for (i = 0; i < size; i++) { - index = (pt == ROOK ? rook_index(s, occupancy[i]) - : bishop_index(s, occupancy[i])); + Bitboard& attack = attacks[s][get_index(s, occupancy[i])]; - if (!attacks[s][index]) - attacks[s][index] = reference[i]; - - else if (attacks[s][index] != reference[i]) + if (attack && attack != reference[i]) break; + + attack = reference[i]; } } while (i != size); }