/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
+ 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 memset
#include "bitboard.h"
-#include "bitcount.h"
-#include "rkiss.h"
+#include "misc.h"
-CACHE_LINE_ALIGNMENT
+uint8_t PopCnt16[1 << 16];
+int SquareDistance[SQUARE_NB][SQUARE_NB];
-Bitboard RMasks[SQUARE_NB];
-Bitboard RMagics[SQUARE_NB];
-Bitboard* RAttacks[SQUARE_NB];
-unsigned RShifts[SQUARE_NB];
+Bitboard RookMasks [SQUARE_NB];
+Bitboard RookMagics [SQUARE_NB];
+Bitboard* RookAttacks[SQUARE_NB];
+unsigned RookShifts [SQUARE_NB];
-Bitboard BMasks[SQUARE_NB];
-Bitboard BMagics[SQUARE_NB];
-Bitboard* BAttacks[SQUARE_NB];
-unsigned BShifts[SQUARE_NB];
+Bitboard BishopMasks [SQUARE_NB];
+Bitboard BishopMagics [SQUARE_NB];
+Bitboard* BishopAttacks[SQUARE_NB];
+unsigned BishopShifts [SQUARE_NB];
Bitboard SquareBB[SQUARE_NB];
Bitboard FileBB[FILE_NB];
Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
Bitboard LineBB[SQUARE_NB][SQUARE_NB];
-Bitboard DistanceRingsBB[SQUARE_NB][8];
+Bitboard DistanceRingBB[SQUARE_NB][8];
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];
-int SquareDistance[SQUARE_NB][SQUARE_NB];
-
namespace {
// De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan
- const uint64_t DeBruijn_64 = 0x3F79D71B4CB0A89ULL;
- const uint32_t DeBruijn_32 = 0x783A9B23;
+ const uint64_t DeBruijn64 = 0x3F79D71B4CB0A89ULL;
+ const uint32_t DeBruijn32 = 0x783A9B23;
- CACHE_LINE_ALIGNMENT
-
- int MS1BTable[256];
- Square BSFTable[SQUARE_NB];
- Bitboard RTable[0x19000]; // Storage space for rook attacks
- Bitboard BTable[0x1480]; // Storage space for bishop attacks
+ 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);
- FORCE_INLINE unsigned bsf_index(Bitboard b) {
+ // 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.
- // Matt Taylor's folding for 32 bit systems, extended to 64 bits by Kim Walisch
- b ^= (b - 1);
- return Is64Bit ? (b * DeBruijn_64) >> 58
- : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn_32) >> 26;
+ unsigned bsf_index(Bitboard b) {
+ b ^= b - 1;
+ return Is64Bit ? (b * DeBruijn64) >> 58
+ : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn32) >> 26;
}
-}
-/// lsb()/msb() finds the least/most significant bit in a non-zero bitboard.
-/// pop_lsb() finds and clears the least significant bit in a non-zero bitboard.
-#ifndef USE_BSFQ
+ // 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;
+ }
+}
-Square lsb(Bitboard b) { return BSFTable[bsf_index(b)]; }
+#ifdef NO_BSF
-Square pop_lsb(Bitboard* b) {
+/// Software fall-back of lsb() and msb() for CPU lacking hardware support
- Bitboard bb = *b;
- *b = bb & (bb - 1);
- return BSFTable[bsf_index(bb)];
+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 to be
-/// printed to standard output. This is sometimes useful for debugging.
+/// Bitboards::pretty() returns an ASCII representation of a bitboard suitable
+/// to be printed to standard output. Useful for debugging.
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;
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)
- BSFTable[bsf_index(SquareBB[s] = 1ULL << s)] = 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;
for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
if (s1 != s2)
{
- SquareDistance[s1][s2] = std::max(file_distance(s1, s2), rank_distance(s1, s2));
- DistanceRingsBB[s1][SquareDistance[s1][s2] - 1] |= s2;
+ SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
+ DistanceRingBB[s1][SquareDistance[s1][s2] - 1] |= s2;
}
int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 },
{
Square to = s + Square(c == WHITE ? steps[pt][i] : -steps[pt][i]);
- if (is_ok(to) && square_distance(s, to) < 3)
+ if (is_ok(to) && distance(s, to) < 3)
StepAttacksBB[make_piece(c, pt)][s] |= to;
}
- Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
- Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
+ Square RookDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
+ Square BishopDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
- init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, magic_index<ROOK>);
- init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, magic_index<BISHOP>);
+ init_magics(RookTable, RookAttacks, RookMagics, RookMasks, RookShifts, RookDeltas, magic_index<ROOK>);
+ init_magics(BishopTable, BishopAttacks, BishopMagics, BishopMasks, BishopShifts, 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 (Piece pc = W_BISHOP; pc <= W_ROOK; ++pc)
+ for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
+ {
+ if (!(PseudoAttacks[pc][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(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]);
+ }
}
}
for (int i = 0; i < 4; ++i)
for (Square s = sq + deltas[i];
- is_ok(s) && square_distance(s, s - deltas[i]) == 1;
+ is_ok(s) && distance(s, s - deltas[i]) == 1;
s += deltas[i])
{
attack |= s;
void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[],
Bitboard masks[], unsigned shifts[], Square deltas[], Fn index) {
- int MagicBoosters[][8] = { { 969, 1976, 2850, 542, 2069, 2852, 1708, 164 },
- { 3101, 552, 3555, 926, 834, 26, 2131, 1117 } };
+ int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020 },
+ { 728, 10316, 55013, 32803, 12281, 15100, 16645, 255 } };
- RKISS rk;
Bitboard occupancy[4096], reference[4096], edges, b;
- int i, size, booster;
+ 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[].
b = size = 0;
do {
occupancy[size] = b;
- reference[size++] = sliding_attack(deltas, s, b);
+ reference[size] = sliding_attack(deltas, s, b);
+
+ if (HasPext)
+ attacks[s][pext(b, masks[s])] = reference[size];
+
+ size++;
b = (b - masks[s]) & masks[s];
} while (b);
if (s < SQ_H8)
attacks[s + 1] = attacks[s] + size;
- booster = MagicBoosters[Is64Bit][rank_of(s)];
+ if (HasPext)
+ continue;
+
+ PRNG rng(seeds[Is64Bit][rank_of(s)]);
// Find a magic for square 's' picking up an (almost) random number
// until we find the one that passes the verification test.
do {
- do magics[s] = rk.magic_rand<Bitboard>(booster);
- while (popcount<Max15>((magics[s] * masks[s]) >> 56) < 6);
-
- std::memset(attacks[s], 0, size * sizeof(Bitboard));
+ do
+ magics[s] = rng.sparse_rand<Bitboard>();
+ 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.
// Note that we build up the database for square 's' as a side
// effect of verifying the magic.
- for (i = 0; i < size; ++i)
+ for (++current, i = 0; i < size; ++i)
{
- Bitboard& attack = attacks[s][index(s, occupancy[i])];
-
- if (attack && attack != reference[i])
+ unsigned idx = index(s, occupancy[i]);
+
+ if (age[idx] < current)
+ {
+ age[idx] = current;
+ attacks[s][idx] = reference[i];
+ }
+ else if (attacks[s][idx] != reference[i])
break;
-
- assert(reference[i]);
-
- attack = reference[i];
}
} while (i < size);
}
projects / stockfish / blobdiff