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  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
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  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
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  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
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  Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
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  Stockfish is free software: you can redistribute it and/or modify
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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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  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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  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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  (at your option) any later version.
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Magic RookMagics[SQUARE_NB];
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Magic RookMagics[SQUARE_NB];
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Magic BishopMagics[SQUARE_NB];
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Magic BishopMagics[SQUARE_NB];
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namespace {
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namespace {
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  // De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan
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  const uint64_t DeBruijn64 = 0x3F79D71B4CB0A89ULL;
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  const uint32_t DeBruijn32 = 0x783A9B23;
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  int MSBTable[256];            // To implement software msb()
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  Square BSFTable[SQUARE_NB];   // To implement software bitscan
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  Bitboard RookTable[0x19000];  // To store rook attacks
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  Bitboard RookTable[0x19000];  // To store rook attacks
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  Bitboard BishopTable[0x1480]; // To store bishop attacks
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  Bitboard BishopTable[0x1480]; // To store bishop attacks
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  void init_magics(Bitboard table[], Magic magics[], Direction directions[]);
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  void init_magics(Bitboard table[], Magic magics[], Direction directions[]);
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  // bsf_index() returns the index into BSFTable[] to look up the bitscan. Uses
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  // Matt Taylor's folding for 32 bit case, extended to 64 bit by Kim Walisch.
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  unsigned bsf_index(Bitboard b) {
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    b ^= b - 1;
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    return Is64Bit ? (b * DeBruijn64) >> 58
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                   : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn32) >> 26;
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  }
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  // popcount16() counts the non-zero bits using SWAR-Popcount algorithm
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  // popcount16() counts the non-zero bits using SWAR-Popcount algorithm
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  unsigned popcount16(unsigned u) {
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  unsigned popcount16(unsigned u) {
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    u -= (u >> 1) & 0x5555U;
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    u -= (u >> 1) & 0x5555U;
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    u = ((u >> 2) & 0x3333U) + (u & 0x3333U);
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    u = ((u >> 2) & 0x3333U) + (u & 0x3333U);
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    u = ((u >> 4) + u) & 0x0F0FU;
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    u = ((u >> 4) + u) & 0x0F0FU;
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    return (u * 0x0101U) >> 8;
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    return (u * 0x0101U) >> 8;
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  }
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  }
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}
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}
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#ifdef NO_BSF
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/// Software fall-back of lsb() and msb() for CPU lacking hardware support
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Square lsb(Bitboard b) {
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  assert(b);
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  return BSFTable[bsf_index(b)];
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}
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Square msb(Bitboard b) {
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  assert(b);
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  unsigned b32;
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  int result = 0;
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  if (b > 0xFFFFFFFF)
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  {
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      b >>= 32;
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      result = 32;
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  }
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  b32 = unsigned(b);
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  if (b32 > 0xFFFF)
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  {
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      b32 >>= 16;
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      result += 16;
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  }
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  if (b32 > 0xFF)
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  {
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      b32 >>= 8;
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      result += 8;
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  }
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  return Square(result + MSBTable[b32]);
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}
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#endif // ifdef NO_BSF
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/// Bitboards::pretty() returns an ASCII representation of a bitboard suitable
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/// Bitboards::pretty() returns an ASCII representation of a bitboard suitable
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/// to be printed to standard output. Useful for debugging.
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/// to be printed to standard output. Useful for debugging.
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  for (unsigned i = 0; i < (1 << 16); ++i)
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  for (unsigned i = 0; i < (1 << 16); ++i)
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      PopCnt16[i] = (uint8_t) popcount16(i);
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      PopCnt16[i] = (uint8_t) popcount16(i);
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  for (Square s = SQ_A1; s <= SQ_H8; ++s)
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  for (Square s = SQ_A1; s <= SQ_H8; ++s)
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  {
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      SquareBB[s] = 1ULL << s;
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      SquareBB[s] = (1ULL << s);
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      BSFTable[bsf_index(SquareBB[s])] = s;
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  }
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  for (Bitboard b = 2; b < 256; ++b)
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      MSBTable[b] = MSBTable[b - 1] + !more_than_one(b);
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  for (File f = FILE_A; f <= FILE_H; ++f)
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  for (File f = FILE_A; f <= FILE_H; ++f)
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      FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB;
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      FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB;
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  for (Rank r = RANK_1; r <= RANK_8; ++r)
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  for (Rank r = RANK_1; r <= RANK_8; ++r)
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  for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
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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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      for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
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          if (s1 != s2)
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          if (s1 != s2)
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          {
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          {
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              SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
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              SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
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              DistanceRingBB[s1][SquareDistance[s1][s2] - 1] |= s2;
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              DistanceRingBB[s1][SquareDistance[s1][s2]] |= s2;
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          }
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          }
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  int steps[][5] = { {}, { 7, 9 }, { 6, 10, 15, 17 }, {}, {}, {}, { 1, 7, 8, 9 } };
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  int steps[][5] = { {}, { 7, 9 }, { 6, 10, 15, 17 }, {}, {}, {}, { 1, 7, 8, 9 } };
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  for (Color c = WHITE; c <= BLACK; ++c)
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  for (Color c = WHITE; c <= BLACK; ++c)
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                      else
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                      else
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                          PseudoAttacks[pt][s] |= to;
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                          PseudoAttacks[pt][s] |= to;
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                  }
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                  }
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              }
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              }
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  Direction RookDirections[] = { NORTH,  EAST,  SOUTH,  WEST };
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  Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST };
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  Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
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  Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
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  init_magics(RookTable, RookMagics, RookDirections);
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  init_magics(RookTable, RookMagics, RookDirections);
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  init_magics(BishopTable, BishopMagics, BishopDirections);
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  init_magics(BishopTable, BishopMagics, BishopDirections);
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