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) 2015-2016 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
*/
#include <algorithm>
-#include <cstring> // 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];
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
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;
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
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;
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;
StepAttacksBB[make_piece(c, 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<ROOK>);
init_magics(BishopTable, BishopAttacks, BishopMagics, BishopMasks, BishopShifts, BishopDeltas, magic_index<BISHOP>);
{ 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;
// 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<Max15>(masks[s]);
+ shifts[s] = (Is64Bit ? 64 : 32) - popcount(masks[s]);
// Use Carry-Rippler trick to enumerate all subsets of masks[s] and
// store the corresponding sliding attack bitboard in reference[].
do {
do
magics[s] = rng.sparse_rand<Bitboard>();
- while (popcount<Max15>((magics[s] * masks[s]) >> 56) < 6);
+ while (popcount((magics[s] * masks[s]) >> 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.