X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=99070ef2c0a6f9e606781517af9a4a213c91cb35;hp=f76ed31c3c8263cd7cfb87698f658ed6caab8555;hb=659990b43ff1a089be9878561048fa4c60ba2705;hpb=6c040c821a50475840607ef5f11c270ee21d61da diff --git a/src/bitboard.cpp b/src/bitboard.cpp index f76ed31c..99070ef2 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 @@ -18,30 +19,21 @@ */ #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]; +Magic RookMagics[SQUARE_NB]; +Magic BishopMagics[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 BetweenBB[SQUARE_NB][SQUARE_NB]; Bitboard LineBB[SQUARE_NB][SQUARE_NB]; Bitboard DistanceRingBB[SQUARE_NB][8]; @@ -49,6 +41,7 @@ Bitboard ForwardBB[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]; namespace { @@ -56,15 +49,14 @@ namespace { const uint64_t DeBruijn64 = 0x3F79D71B4CB0A89ULL; const uint32_t DeBruijn32 = 0x783A9B23; - int MS1BTable[256]; // To implement software msb() + int MSBTable[256]; // To implement software msb() Square BSFTable[SQUARE_NB]; // To implement software bitscan 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[], Fn index); // 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 +66,30 @@ 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; @@ -109,10 +113,10 @@ Square msb(Bitboard b) { result += 8; } - return Square(result + MS1BTable[b32]); + return Square(result + MSBTable[b32]); } -#endif // ifndef USE_BSFQ +#endif // ifdef NO_BSF /// Bitboards::pretty() returns an ASCII representation of a bitboard suitable @@ -125,9 +129,9 @@ const std::string Bitboards::pretty(Bitboard b) { for (Rank r = RANK_8; r >= RANK_1; --r) { for (File f = FILE_A; f <= FILE_H; ++f) - s.append(b & make_square(f, r) ? "| X " : "| "); + s += b & make_square(f, r) ? "| X " : "| "; - s.append("|\n+---+---+---+---+---+---+---+---+\n"); + s += "|\n+---+---+---+---+---+---+---+---+\n"; } return s; @@ -139,14 +143,17 @@ 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; BSFTable[bsf_index(SquareBB[s])] = s; } - for (Bitboard b = 1; b < 256; ++b) - MS1BTable[b] = more_than_one(b) ? MS1BTable[b - 1] : lsb(b); + for (Bitboard b = 2; b < 256; ++b) + MSBTable[b] = MSBTable[b - 1] + !more_than_one(b); for (File f = FILE_A; f <= FILE_H; ++f) FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB; @@ -176,42 +183,44 @@ 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, magic_index); + init_magics(BishopTable, BishopMagics, BishopDeltas, magic_index); 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 (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) - { - Piece pc = (PseudoAttacks[BISHOP][s1] & s2) ? W_BISHOP : - (PseudoAttacks[ROOK][s1] & s2) ? W_ROOK : NO_PIECE; - - if (pc == NO_PIECE) - continue; + 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(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]); + } } } @@ -242,19 +251,16 @@ 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[], Fn index) { 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)); + int age[4096] = {0}, current = 0, i, size; // attacks[s] is a pointer to the beginning of the attacks table for square 's' - attacks[SQ_A1] = table; + magics[SQ_A1].attacks = table; for (Square s = SQ_A1; s <= SQ_H8; ++s) { @@ -266,8 +272,8 @@ 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]); + magics[s].mask = sliding_attack(deltas, s, 0) & ~edges; + magics[s].shift = (Is64Bit ? 64 : 32) - popcount(magics[s].mask); // Use Carry-Rippler trick to enumerate all subsets of masks[s] and // store the corresponding sliding attack bitboard in reference[]. @@ -277,16 +283,16 @@ namespace { reference[size] = sliding_attack(deltas, s, b); if (HasPext) - attacks[s][pext(b, masks[s])] = reference[size]; + magics[s].attacks[pext(b, magics[s].mask)] = reference[size]; size++; - b = (b - masks[s]) & masks[s]; + b = (b - magics[s].mask) & magics[s].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; + magics[s + 1].attacks = magics[s].attacks + size; if (HasPext) continue; @@ -297,8 +303,8 @@ namespace { // 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); + magics[s].magic = rng.sparse_rand(); + while (popcount((magics[s].magic * magics[s].mask) >> 56) < 6); // A good magic must map every possible occupancy to an index that // looks up the correct sliding attack in the attacks[s] database. @@ -311,9 +317,9 @@ namespace { if (age[idx] < current) { age[idx] = current; - attacks[s][idx] = reference[i]; + magics[s].attacks[idx] = reference[i]; } - else if (attacks[s][idx] != reference[i]) + else if (magics[s].attacks[idx] != reference[i]) break; } } while (i < size);