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
*/
#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];
-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];
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 {
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.
- FORCE_INLINE unsigned bsf_index(Bitboard b) {
+ unsigned bsf_index(Bitboard b) {
b ^= b - 1;
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;
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<ROOK>);
- init_magics(BishopTable, BishopAttacks, BishopMagics, BishopMasks, BishopShifts, BishopDeltas, magic_index<BISHOP>);
+ init_magics(RookTable, RookMagics, RookDeltas, magic_index<ROOK>);
+ init_magics(BishopTable, BishopMagics, BishopDeltas, magic_index<BISHOP>);
for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
{
PseudoAttacks[QUEEN][s1] = PseudoAttacks[BISHOP][s1] = attacks_bb<BISHOP>(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]);
+ }
}
}
// 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)
{
// 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<Max15>(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[].
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;
// until we find the one that passes the verification test.
do {
do
- magics[s] = rng.sparse_rand<Bitboard>();
- while (popcount<Max15>((magics[s] * masks[s]) >> 56) < 6);
+ magics[s].magic = rng.sparse_rand<Bitboard>();
+ 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.
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);
projects / stockfish / blobdiff