X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=04d12c5ebfe389d942a85236542a75b0cf095d90;hp=e0533bc9cc286280c61432c455adf41ee3695ebe;hb=6d24ef8585c2ed5618eb9b4ab1d8ee35a05ce2cd;hpb=112607bf490ccdeaf3446996c6c4f09a11778c7b diff --git a/src/bitboard.cpp b/src/bitboard.cpp index e0533bc9..04d12c5e 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -2,6 +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) 2015-2017 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 @@ -18,37 +19,29 @@ */ #include -#include // For std::memset #include "bitboard.h" -#include "bitcount.h" #include "misc.h" +uint8_t PopCnt16[1 << 16]; int SquareDistance[SQUARE_NB][SQUARE_NB]; -Bitboard RookMasks [SQUARE_NB]; -Bitboard RookMagics [SQUARE_NB]; -Bitboard* RookAttacks[SQUARE_NB]; -unsigned RookShifts [SQUARE_NB]; - -Bitboard BishopMasks [SQUARE_NB]; -Bitboard BishopMagics [SQUARE_NB]; -Bitboard* BishopAttacks[SQUARE_NB]; -unsigned BishopShifts [SQUARE_NB]; - Bitboard SquareBB[SQUARE_NB]; Bitboard FileBB[FILE_NB]; Bitboard RankBB[RANK_NB]; Bitboard AdjacentFilesBB[FILE_NB]; -Bitboard InFrontBB[COLOR_NB][RANK_NB]; -Bitboard StepAttacksBB[PIECE_NB][SQUARE_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 ForwardBB[COLOR_NB][SQUARE_NB]; +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]; + +Magic RookMagics[SQUARE_NB]; +Magic BishopMagics[SQUARE_NB]; namespace { @@ -61,10 +54,7 @@ namespace { Bitboard RookTable[0x19000]; // To store rook attacks Bitboard BishopTable[0x1480]; // To store bishop attacks - typedef unsigned (Fn)(Square, Bitboard); - - void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], unsigned shifts[], Square deltas[], Fn index); + void init_magics(Bitboard table[], Magic magics[], Square deltas[]); // bsf_index() returns the index into BSFTable[] to look up the bitscan. Uses // Matt Taylor's folding for 32 bit case, extended to 64 bit by Kim Walisch. @@ -74,18 +64,30 @@ namespace { return Is64Bit ? (b * DeBruijn64) >> 58 : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn32) >> 26; } + + + // 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; + } } -#ifndef USE_BSFQ +#ifdef NO_BSF /// Software fall-back of lsb() and msb() for CPU lacking hardware support Square lsb(Bitboard b) { + assert(b); return BSFTable[bsf_index(b)]; } Square msb(Bitboard b) { + assert(b); unsigned b32; int result = 0; @@ -112,7 +114,7 @@ Square msb(Bitboard b) { return Square(result + MSBTable[b32]); } -#endif // ifndef USE_BSFQ +#endif // ifdef NO_BSF /// Bitboards::pretty() returns an ASCII representation of a bitboard suitable @@ -139,6 +141,9 @@ const std::string Bitboards::pretty(Bitboard b) { void Bitboards::init() { + for (unsigned i = 0; i < (1 << 16); ++i) + PopCnt16[i] = (uint8_t) popcount16(i); + for (Square s = SQ_A1; s <= SQ_H8; ++s) { SquareBB[s] = 1ULL << s; @@ -158,14 +163,14 @@ void Bitboards::init() { AdjacentFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0); for (Rank r = RANK_1; r < RANK_8; ++r) - InFrontBB[WHITE][r] = ~(InFrontBB[BLACK][r + 1] = InFrontBB[BLACK][r] | RankBB[r]); + ForwardRanksBB[WHITE][r] = ~(ForwardRanksBB[BLACK][r + 1] = ForwardRanksBB[BLACK][r] | RankBB[r]); for (Color c = WHITE; c <= BLACK; ++c) for (Square s = SQ_A1; s <= SQ_H8; ++s) { - ForwardBB[c][s] = InFrontBB[c][rank_of(s)] & FileBB[file_of(s)]; - PawnAttackSpan[c][s] = InFrontBB[c][rank_of(s)] & AdjacentFilesBB[file_of(s)]; - PassedPawnMask[c][s] = ForwardBB[c][s] | PawnAttackSpan[c][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 s1 = SQ_A1; s1 <= SQ_H8; ++s1) @@ -176,39 +181,43 @@ void Bitboards::init() { DistanceRingBB[s1][SquareDistance[s1][s2] - 1] |= s2; } - int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 }, - {}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } }; + int steps[][5] = { {}, { 7, 9 }, { 6, 10, 15, 17 }, {}, {}, {}, { 1, 7, 8, 9 } }; for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = PAWN; pt <= KING; ++pt) + 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 + Square(c == WHITE ? steps[pt][i] : -steps[pt][i]); if (is_ok(to) && distance(s, to) < 3) - StepAttacksBB[make_piece(c, pt)][s] |= to; + { + if (pt == PAWN) + PawnAttacks[c][s] |= to; + else + PseudoAttacks[pt][s] |= to; + } } - Square RookDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W }; - Square BishopDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW }; + Square RookDeltas[] = { NORTH, EAST, SOUTH, WEST }; + Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; - init_magics(RookTable, RookAttacks, RookMagics, RookMasks, RookShifts, RookDeltas, magic_index); - init_magics(BishopTable, BishopAttacks, BishopMagics, BishopMasks, BishopShifts, BishopDeltas, magic_index); + init_magics(RookTable, RookMagics, RookDeltas); + init_magics(BishopTable, BishopMagics, BishopDeltas); for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) { PseudoAttacks[QUEEN][s1] = PseudoAttacks[BISHOP][s1] = attacks_bb(s1, 0); PseudoAttacks[QUEEN][s1] |= PseudoAttacks[ ROOK][s1] = attacks_bb< ROOK>(s1, 0); - for (Piece pc = W_BISHOP; pc <= W_ROOK; ++pc) + for (PieceType pt : { BISHOP, ROOK }) for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) { - if (!(PseudoAttacks[pc][s1] & s2)) + if (!(PseudoAttacks[pt][s1] & s2)) continue; - LineBB[s1][s2] = (attacks_bb(pc, s1, 0) & attacks_bb(pc, s2, 0)) | s1 | s2; - BetweenBB[s1][s2] = attacks_bb(pc, s1, SquareBB[s2]) & attacks_bb(pc, s2, SquareBB[s1]); + 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]); } } } @@ -240,19 +249,13 @@ namespace { // chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we // use the so called "fancy" approach. - void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], unsigned shifts[], Square deltas[], Fn index) { + void init_magics(Bitboard table[], Magic magics[], Square deltas[]) { int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020 }, { 728, 10316, 55013, 32803, 12281, 15100, 16645, 255 } }; Bitboard occupancy[4096], reference[4096], edges, b; - int age[4096], current = 0, i, size; - - std::memset(age, 0, sizeof(age)); - - // attacks[s] is a pointer to the beginning of the attacks table for square 's' - attacks[SQ_A1] = table; + int epoch[4096] = {}, cnt = 0, size = 0; for (Square s = SQ_A1; s <= SQ_H8; ++s) { @@ -264,8 +267,13 @@ 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_attack(deltas, s, 0) & ~edges; - shifts[s] = (Is64Bit ? 64 : 32) - popcount(masks[s]); + Magic& m = magics[s]; + m.mask = sliding_attack(deltas, s, 0) & ~edges; + m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask); + + // Set the offset for the attacks table of the square. We have individual + // table sizes for each square with "Fancy Magic Bitboards". + m.attacks = s == SQ_A1 ? table : magics[s - 1].attacks + size; // Use Carry-Rippler trick to enumerate all subsets of masks[s] and // store the corresponding sliding attack bitboard in reference[]. @@ -275,17 +283,12 @@ namespace { reference[size] = sliding_attack(deltas, s, b); if (HasPext) - attacks[s][pext(b, masks[s])] = reference[size]; + m.attacks[pext(b, m.mask)] = reference[size]; size++; - b = (b - masks[s]) & masks[s]; + b = (b - m.mask) & m.mask; } while (b); - // Set the offset for the table of the next square. We have individual - // table sizes for each square with "Fancy Magic Bitboards". - if (s < SQ_H8) - attacks[s + 1] = attacks[s] + size; - if (HasPext) continue; @@ -293,28 +296,30 @@ namespace { // Find a magic for square 's' picking up an (almost) random number // until we find the one that passes the verification test. - do { - do - magics[s] = rng.sparse_rand(); - while (popcount((magics[s] * masks[s]) >> 56) < 6); + for (int i = 0; i < size; ) + { + for (m.magic = 0; popcount((m.magic * m.mask) >> 56) < 6; ) + m.magic = rng.sparse_rand(); // A good magic must map every possible occupancy to an index that // looks up the correct sliding attack in the attacks[s] database. // Note that we build up the database for square 's' as a side - // effect of verifying the magic. - for (++current, i = 0; i < size; ++i) + // effect of verifying the magic. Keep track of the attempt count + // and save it in epoch[], little speed-up trick to avoid resetting + // m.attacks[] after every failed attempt. + for (++cnt, i = 0; i < size; ++i) { - unsigned idx = index(s, occupancy[i]); + unsigned idx = m.index(occupancy[i]); - if (age[idx] < current) + if (epoch[idx] < cnt) { - age[idx] = current; - attacks[s][idx] = reference[i]; + epoch[idx] = cnt; + m.attacks[idx] = reference[i]; } - else if (attacks[s][idx] != reference[i]) + else if (m.attacks[idx] != reference[i]) break; } - } while (i < size); + } } } }