mirror of
https://github.com/sockspls/badfish
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fe26967ea0
Easy, almost trivial simplification, I don't understand how I missed this before !! No functional change. Signed-off-by: Marco Costalba <mcostalba@gmail.com>
344 lines
9.8 KiB
C++
344 lines
9.8 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <cstring>
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#include <iostream>
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#include "bitboard.h"
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#include "bitcount.h"
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#include "rkiss.h"
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// Global bitboards definitions with static storage duration are
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// automatically set to zero before enter main().
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Bitboard RMask[64];
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Bitboard RMult[64];
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Bitboard* RAttacks[64];
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int RShift[64];
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Bitboard BMask[64];
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Bitboard BMult[64];
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Bitboard* BAttacks[64];
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int BShift[64];
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Bitboard SetMaskBB[65];
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Bitboard ClearMaskBB[65];
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Bitboard SquaresByColorBB[2];
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Bitboard FileBB[8];
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Bitboard RankBB[8];
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Bitboard NeighboringFilesBB[8];
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Bitboard ThisAndNeighboringFilesBB[8];
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Bitboard InFrontBB[2][8];
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Bitboard StepAttacksBB[16][64];
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Bitboard BetweenBB[64][64];
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Bitboard SquaresInFrontMask[2][64];
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Bitboard PassedPawnMask[2][64];
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Bitboard AttackSpanMask[2][64];
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Bitboard BishopPseudoAttacks[64];
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Bitboard RookPseudoAttacks[64];
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Bitboard QueenPseudoAttacks[64];
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uint8_t BitCount8Bit[256];
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namespace {
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CACHE_LINE_ALIGNMENT
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int BSFTable[64];
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Bitboard RAttacksTable[0x19000];
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Bitboard BAttacksTable[0x1480];
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void init_sliding_attacks(Bitboard magic[], Bitboard* attack[], Bitboard attTable[],
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Bitboard mask[], int shift[], Square delta[]);
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}
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/// print_bitboard() prints a bitboard in an easily readable format to the
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/// standard output. This is sometimes useful for debugging.
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void print_bitboard(Bitboard b) {
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for (Rank r = RANK_8; r >= RANK_1; r--)
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{
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std::cout << "+---+---+---+---+---+---+---+---+" << '\n';
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for (File f = FILE_A; f <= FILE_H; f++)
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std::cout << "| " << (bit_is_set(b, make_square(f, r)) ? "X " : " ");
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std::cout << "|\n";
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}
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std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
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}
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/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
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/// pop_1st_bit() finds and clears the least significant nonzero bit in a
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/// nonzero bitboard.
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#if defined(IS_64BIT) && !defined(USE_BSFQ)
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Square first_1(Bitboard b) {
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return Square(BSFTable[((b & -b) * 0x218A392CD3D5DBFULL) >> 58]);
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}
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Square pop_1st_bit(Bitboard* b) {
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Bitboard bb = *b;
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*b &= (*b - 1);
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return Square(BSFTable[((bb & -bb) * 0x218A392CD3D5DBFULL) >> 58]);
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}
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#elif !defined(USE_BSFQ)
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Square first_1(Bitboard b) {
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b ^= (b - 1);
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uint32_t fold = unsigned(b) ^ unsigned(b >> 32);
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return Square(BSFTable[(fold * 0x783A9B23) >> 26]);
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}
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// Use type-punning
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union b_union {
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Bitboard b;
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struct {
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#if defined (BIGENDIAN)
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uint32_t h;
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uint32_t l;
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#else
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uint32_t l;
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uint32_t h;
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#endif
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} dw;
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};
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Square pop_1st_bit(Bitboard* bb) {
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b_union u;
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Square ret;
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u.b = *bb;
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if (u.dw.l)
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{
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ret = Square(BSFTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783A9B23) >> 26]);
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u.dw.l &= (u.dw.l - 1);
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*bb = u.b;
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return ret;
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}
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ret = Square(BSFTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783A9B23) >> 26]);
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u.dw.h &= (u.dw.h - 1);
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*bb = u.b;
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return ret;
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}
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#endif // !defined(USE_BSFQ)
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/// init_bitboards() initializes various bitboard arrays. It is called during
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/// program initialization.
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void init_bitboards() {
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SquaresByColorBB[DARK] = 0xAA55AA55AA55AA55ULL;
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SquaresByColorBB[LIGHT] = ~SquaresByColorBB[DARK];
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for (Square s = SQ_A1; s <= SQ_H8; s++)
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{
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SetMaskBB[s] = 1ULL << s;
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ClearMaskBB[s] = ~SetMaskBB[s];
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}
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ClearMaskBB[SQ_NONE] = ~EmptyBoardBB;
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FileBB[FILE_A] = FileABB;
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RankBB[RANK_1] = Rank1BB;
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for (int f = FILE_B; f <= FILE_H; f++)
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{
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FileBB[f] = FileBB[f - 1] << 1;
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RankBB[f] = RankBB[f - 1] << 8;
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}
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for (int f = FILE_A; f <= FILE_H; f++)
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{
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NeighboringFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0);
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ThisAndNeighboringFilesBB[f] = FileBB[f] | NeighboringFilesBB[f];
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}
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for (int rw = RANK_7, rb = RANK_2; rw >= RANK_1; rw--, rb++)
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{
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InFrontBB[WHITE][rw] = InFrontBB[WHITE][rw + 1] | RankBB[rw + 1];
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InFrontBB[BLACK][rb] = InFrontBB[BLACK][rb - 1] | RankBB[rb - 1];
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}
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for (Color c = WHITE; c <= BLACK; c++)
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for (Square s = SQ_A1; s <= SQ_H8; s++)
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{
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SquaresInFrontMask[c][s] = in_front_bb(c, s) & file_bb(s);
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PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s);
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AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
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}
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for (Bitboard b = 0; b < 256; b++)
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BitCount8Bit[b] = (uint8_t)count_1s<CNT32_MAX15>(b);
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for (int i = 0; i < 64; i++)
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if (!CpuIs64Bit) // Matt Taylor's folding trick for 32 bit systems
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{
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Bitboard b = 1ULL << i;
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b ^= b - 1;
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b ^= b >> 32;
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BSFTable[uint32_t(b * 0x783A9B23) >> 26] = i;
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}
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else
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BSFTable[((1ULL << i) * 0x218A392CD3D5DBFULL) >> 58] = i;
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int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 },
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{}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } };
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for (Color c = WHITE; c <= BLACK; c++)
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for (PieceType pt = PAWN; pt <= KING; pt++)
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for (Square s = SQ_A1; s <= SQ_H8; s++)
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for (int k = 0; steps[pt][k]; k++)
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{
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Square to = s + Square(c == WHITE ? steps[pt][k] : -steps[pt][k]);
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if (square_is_ok(to) && square_distance(s, to) < 3)
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set_bit(&StepAttacksBB[make_piece(c, pt)][s], to);
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}
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Square RDelta[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
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Square BDelta[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
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init_sliding_attacks(BMult, BAttacks, BAttacksTable, BMask, BShift, BDelta);
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init_sliding_attacks(RMult, RAttacks, RAttacksTable, RMask, RShift, RDelta);
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for (Square s = SQ_A1; s <= SQ_H8; s++)
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{
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BishopPseudoAttacks[s] = bishop_attacks_bb(s, EmptyBoardBB);
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RookPseudoAttacks[s] = rook_attacks_bb(s, EmptyBoardBB);
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QueenPseudoAttacks[s] = queen_attacks_bb(s, EmptyBoardBB);
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}
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for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
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for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
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if (bit_is_set(QueenPseudoAttacks[s1], s2))
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{
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int f = file_distance(s1, s2);
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int r = rank_distance(s1, s2);
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Square d = (s2 - s1) / Max(f, r);
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for (Square s3 = s1 + d; s3 != s2; s3 += d)
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set_bit(&BetweenBB[s1][s2], s3);
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}
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}
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namespace {
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Bitboard sliding_attacks(Square sq, Bitboard occupied, Square delta[]) {
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Bitboard attacks = 0;
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for (int i = 0; i < 4; i++)
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{
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Square s = sq + delta[i];
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while (square_is_ok(s) && square_distance(s, s - delta[i]) == 1)
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{
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set_bit(&attacks, s);
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if (bit_is_set(occupied, s))
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break;
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s += delta[i];
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}
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}
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return attacks;
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}
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Bitboard pick_magic(Bitboard mask, RKISS& rk, int booster) {
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Bitboard magic;
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// Values s1 and s2 are used to rotate the candidate magic of a
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// quantity known to be the optimal to quickly find the magics.
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int s1 = booster & 63, s2 = (booster >> 6) & 63;
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while (true)
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{
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magic = rk.rand<Bitboard>();
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magic = (magic >> s1) | (magic << (64 - s1));
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magic &= rk.rand<Bitboard>();
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magic = (magic >> s2) | (magic << (64 - s2));
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magic &= rk.rand<Bitboard>();
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if (BitCount8Bit[(mask * magic) >> 56] >= 6)
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return magic;
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}
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}
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void init_sliding_attacks(Bitboard magic[], Bitboard* attack[], Bitboard attTable[],
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Bitboard mask[], int shift[], Square delta[]) {
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const int MagicBoosters[][8] = { { 3191, 2184, 1310, 3618, 2091, 1308, 2452, 3996 },
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{ 1059, 3608, 605, 3234, 3326, 38, 2029, 3043 } };
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RKISS rk;
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Bitboard occupancy[4096], reference[4096], edges, b;
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int key, maxKey, index, booster, offset = 0;
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for (Square s = SQ_A1; s <= SQ_H8; s++)
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{
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edges = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s));
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attack[s] = &attTable[offset];
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mask[s] = sliding_attacks(s, EmptyBoardBB, delta) & ~edges;
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shift[s] = (CpuIs64Bit ? 64 : 32) - count_1s<CNT32_MAX15>(mask[s]);
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// Use Carry-Rippler trick to enumerate all subsets of mask[s]
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b = maxKey = 0;
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do {
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occupancy[maxKey] = b;
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reference[maxKey++] = sliding_attacks(s, b, delta);
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b = (b - mask[s]) & mask[s];
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} while (b);
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offset += maxKey;
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booster = MagicBoosters[CpuIs64Bit][square_rank(s)];
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// Then find a possible magic and the corresponding attacks
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do {
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magic[s] = pick_magic(mask[s], rk, booster);
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memset(attack[s], 0, maxKey * sizeof(Bitboard));
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for (key = 0; key < maxKey; key++)
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{
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index = CpuIs64Bit ? unsigned((occupancy[key] * magic[s]) >> shift[s])
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: unsigned(occupancy[key] * magic[s] ^ (occupancy[key] >> 32) * (magic[s] >> 32)) >> shift[s];
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if (!attack[s][index])
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attack[s][index] = reference[key];
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else if (attack[s][index] != reference[key])
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break;
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}
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} while (key != maxKey);
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}
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}
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}
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