2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
33 const uint64_t BMult[64] = {
34 0x440049104032280ULL, 0x1021023c82008040ULL, 0x404040082000048ULL,
35 0x48c4440084048090ULL, 0x2801104026490000ULL, 0x4100880442040800ULL,
36 0x181011002e06040ULL, 0x9101004104200e00ULL, 0x1240848848310401ULL,
37 0x2000142828050024ULL, 0x1004024d5000ULL, 0x102044400800200ULL,
38 0x8108108820112000ULL, 0xa880818210c00046ULL, 0x4008008801082000ULL,
39 0x60882404049400ULL, 0x104402004240810ULL, 0xa002084250200ULL,
40 0x100b0880801100ULL, 0x4080201220101ULL, 0x44008080a00000ULL,
41 0x202200842000ULL, 0x5006004882d00808ULL, 0x200045080802ULL,
42 0x86100020200601ULL, 0xa802080a20112c02ULL, 0x80411218080900ULL,
43 0x200a0880080a0ULL, 0x9a01010000104000ULL, 0x28008003100080ULL,
44 0x211021004480417ULL, 0x401004188220806ULL, 0x825051400c2006ULL,
45 0x140c0210943000ULL, 0x242800300080ULL, 0xc2208120080200ULL,
46 0x2430008200002200ULL, 0x1010100112008040ULL, 0x8141050100020842ULL,
47 0x822081014405ULL, 0x800c049e40400804ULL, 0x4a0404028a000820ULL,
48 0x22060201041200ULL, 0x360904200840801ULL, 0x881a08208800400ULL,
49 0x60202c00400420ULL, 0x1204440086061400ULL, 0x8184042804040ULL,
50 0x64040315300400ULL, 0xc01008801090a00ULL, 0x808010401140c00ULL,
51 0x4004830c2020040ULL, 0x80005002020054ULL, 0x40000c14481a0490ULL,
52 0x10500101042048ULL, 0x1010100200424000ULL, 0x640901901040ULL,
53 0xa0201014840ULL, 0x840082aa011002ULL, 0x10010840084240aULL,
54 0x420400810420608ULL, 0x8d40230408102100ULL, 0x4a00200612222409ULL,
58 const uint64_t RMult[64] = {
59 0xa8002c000108020ULL, 0x4440200140003000ULL, 0x8080200010011880ULL,
60 0x380180080141000ULL, 0x1a00060008211044ULL, 0x410001000a0c0008ULL,
61 0x9500060004008100ULL, 0x100024284a20700ULL, 0x802140008000ULL,
62 0x80c01002a00840ULL, 0x402004282011020ULL, 0x9862000820420050ULL,
63 0x1001448011100ULL, 0x6432800200800400ULL, 0x40100010002000cULL,
64 0x2800d0010c080ULL, 0x90c0008000803042ULL, 0x4010004000200041ULL,
65 0x3010010200040ULL, 0xa40828028001000ULL, 0x123010008000430ULL,
66 0x24008004020080ULL, 0x60040001104802ULL, 0x582200028400d1ULL,
67 0x4000802080044000ULL, 0x408208200420308ULL, 0x610038080102000ULL,
68 0x3601000900100020ULL, 0x80080040180ULL, 0xc2020080040080ULL,
69 0x80084400100102ULL, 0x4022408200014401ULL, 0x40052040800082ULL,
70 0xb08200280804000ULL, 0x8a80a008801000ULL, 0x4000480080801000ULL,
71 0x911808800801401ULL, 0x822a003002001894ULL, 0x401068091400108aULL,
72 0x4a10a00004cULL, 0x2000800640008024ULL, 0x1486408102020020ULL,
73 0x100a000d50041ULL, 0x810050020b0020ULL, 0x204000800808004ULL,
74 0x20048100a000cULL, 0x112000831020004ULL, 0x9000040810002ULL,
75 0x440490200208200ULL, 0x8910401000200040ULL, 0x6404200050008480ULL,
76 0x4b824a2010010100ULL, 0x4080801810c0080ULL, 0x400802a0080ULL,
77 0x8224080110026400ULL, 0x40002c4104088200ULL, 0x1002100104a0282ULL,
78 0x1208400811048021ULL, 0x3201014a40d02001ULL, 0x5100019200501ULL,
79 0x101000208001005ULL, 0x2008450080702ULL, 0x1002080301d00cULL,
83 const int BShift[64] = {
84 58, 59, 59, 59, 59, 59, 59, 58, 59, 59, 59, 59, 59, 59, 59, 59,
85 59, 59, 57, 57, 57, 57, 59, 59, 59, 59, 57, 55, 55, 57, 59, 59,
86 59, 59, 57, 55, 55, 57, 59, 59, 59, 59, 57, 57, 57, 57, 59, 59,
87 59, 59, 59, 59, 59, 59, 59, 59, 58, 59, 59, 59, 59, 59, 59, 58
90 const int RShift[64] = {
91 52, 53, 53, 53, 53, 53, 53, 52, 53, 54, 54, 54, 54, 54, 54, 53,
92 53, 54, 54, 54, 54, 54, 54, 53, 53, 54, 54, 54, 54, 54, 54, 53,
93 53, 54, 54, 54, 54, 54, 54, 53, 53, 54, 54, 54, 54, 54, 54, 53,
94 53, 54, 54, 54, 54, 54, 54, 53, 52, 53, 53, 53, 53, 53, 53, 52
97 #else // if !defined(IS_64BIT)
99 const uint64_t BMult[64] = {
100 0x54142844c6a22981ULL, 0x710358a6ea25c19eULL, 0x704f746d63a4a8dcULL,
101 0xbfed1a0b80f838c5ULL, 0x90561d5631e62110ULL, 0x2804260376e60944ULL,
102 0x84a656409aa76871ULL, 0xf0267f64c28b6197ULL, 0x70764ebb762f0585ULL,
103 0x92aa09e0cfe161deULL, 0x41ee1f6bb266f60eULL, 0xddcbf04f6039c444ULL,
104 0x5a3fab7bac0d988aULL, 0xd3727877fa4eaa03ULL, 0xd988402d868ddaaeULL,
105 0x812b291afa075c7cULL, 0x94faf987b685a932ULL, 0x3ed867d8470d08dbULL,
106 0x92517660b8901de8ULL, 0x2d97e43e058814b4ULL, 0x880a10c220b25582ULL,
107 0xc7c6520d1f1a0477ULL, 0xdbfc7fbcd7656aa6ULL, 0x78b1b9bfb1a2b84fULL,
108 0x2f20037f112a0bc1ULL, 0x657171ea2269a916ULL, 0xc08302b07142210eULL,
109 0x880a4403064080bULL, 0x3602420842208c00ULL, 0x852800dc7e0b6602ULL,
110 0x595a3fbbaa0f03b2ULL, 0x9f01411558159d5eULL, 0x2b4a4a5f88b394f2ULL,
111 0x4afcbffc292dd03aULL, 0x4a4094a3b3f10522ULL, 0xb06f00b491f30048ULL,
112 0xd5b3820280d77004ULL, 0x8b2e01e7c8e57a75ULL, 0x2d342794e886c2e6ULL,
113 0xc302c410cde21461ULL, 0x111f426f1379c274ULL, 0xe0569220abb31588ULL,
114 0x5026d3064d453324ULL, 0xe2076040c343cd8aULL, 0x93efd1e1738021eeULL,
115 0xb680804bed143132ULL, 0x44e361b21986944cULL, 0x44c60170ef5c598cULL,
116 0xf4da475c195c9c94ULL, 0xa3afbb5f72060b1dULL, 0xbc75f410e41c4ffcULL,
117 0xb51c099390520922ULL, 0x902c011f8f8ec368ULL, 0x950b56b3d6f5490aULL,
118 0x3909e0635bf202d0ULL, 0x5744f90206ec10ccULL, 0xdc59fd76317abbc1ULL,
119 0x881c7c67fcbfc4f6ULL, 0x47ca41e7e440d423ULL, 0xeb0c88112048d004ULL,
120 0x51c60e04359aef1aULL, 0x1aa1fe0e957a5554ULL, 0xdd9448db4f5e3104ULL,
121 0xdc01f6dca4bebbdcULL,
124 const uint64_t RMult[64] = {
125 0xd7445cdec88002c0ULL, 0xd0a505c1f2001722ULL, 0xe065d1c896002182ULL,
126 0x9a8c41e75a000892ULL, 0x8900b10c89002aa8ULL, 0x9b28d1c1d60005a2ULL,
127 0x15d6c88de002d9aULL, 0xb1dbfc802e8016a9ULL, 0x149a1042d9d60029ULL,
128 0xb9c08050599e002fULL, 0x132208c3af300403ULL, 0xc1000ce2e9c50070ULL,
129 0x9d9aa13c99020012ULL, 0xb6b078daf71e0046ULL, 0x9d880182fb6e002eULL,
130 0x52889f467e850037ULL, 0xda6dc008d19a8480ULL, 0x468286034f902420ULL,
131 0x7140ac09dc54c020ULL, 0xd76ffffa39548808ULL, 0xea901c4141500808ULL,
132 0xc91004093f953a02ULL, 0x2882afa8f6bb402ULL, 0xaebe335692442c01ULL,
133 0xe904a22079fb91eULL, 0x13a514851055f606ULL, 0x76c782018c8fe632ULL,
134 0x1dc012a9d116da06ULL, 0x3c9e0037264fffa6ULL, 0x2036002853c6e4a2ULL,
135 0xe3fe08500afb47d4ULL, 0xf38af25c86b025c2ULL, 0xc0800e2182cf9a40ULL,
136 0x72002480d1f60673ULL, 0x2500200bae6e9b53ULL, 0xc60018c1eefca252ULL,
137 0x600590473e3608aULL, 0x46002c4ab3fe51b2ULL, 0xa200011486bcc8d2ULL,
138 0xb680078095784c63ULL, 0x2742002639bf11aeULL, 0xc7d60021a5bdb142ULL,
139 0xc8c04016bb83d820ULL, 0xbd520028123b4842ULL, 0x9d1600344ac2a832ULL,
140 0x6a808005631c8a05ULL, 0x604600a148d5389aULL, 0xe2e40103d40dea65ULL,
141 0x945b5a0087c62a81ULL, 0x12dc200cd82d28eULL, 0x2431c600b5f9ef76ULL,
142 0xfb142a006a9b314aULL, 0x6870e00a1c97d62ULL, 0x2a9db2004a2689a2ULL,
143 0xd3594600caf5d1a2ULL, 0xee0e4900439344a7ULL, 0x89c4d266ca25007aULL,
144 0x3e0013a2743f97e3ULL, 0x180e31a0431378aULL, 0x3a9e465a4d42a512ULL,
145 0x98d0a11a0c0d9cc2ULL, 0x8e711c1aba19b01eULL, 0x8dcdc836dd201142ULL,
146 0x5ac08a4735370479ULL,
149 const int BShift[64] = {
150 26, 27, 27, 27, 27, 27, 27, 26, 27, 27, 27, 27, 27, 27, 27, 27,
151 27, 27, 25, 25, 25, 25, 27, 27, 27, 27, 25, 23, 23, 25, 27, 27,
152 27, 27, 25, 23, 23, 25, 27, 27, 27, 27, 25, 25, 25, 25, 27, 27,
153 27, 27, 27, 27, 27, 27, 27, 27, 26, 27, 27, 27, 27, 27, 27, 26
156 const int RShift[64] = {
157 20, 21, 21, 21, 21, 21, 21, 20, 21, 22, 22, 22, 22, 22, 22, 21,
158 21, 22, 22, 22, 22, 22, 22, 21, 21, 22, 22, 22, 22, 22, 22, 21,
159 21, 22, 22, 22, 22, 22, 22, 21, 21, 22, 22, 22, 22, 22, 22, 21,
160 21, 22, 22, 22, 22, 22, 22, 21, 20, 21, 21, 21, 21, 21, 21, 20
163 #endif // defined(IS_64BIT)
165 const Bitboard LightSquaresBB = 0x55AA55AA55AA55AAULL;
166 const Bitboard DarkSquaresBB = 0xAA55AA55AA55AA55ULL;
168 const Bitboard SquaresByColorBB[2] = { DarkSquaresBB, LightSquaresBB };
170 const Bitboard FileBB[8] = {
171 FileABB, FileBBB, FileCBB, FileDBB, FileEBB, FileFBB, FileGBB, FileHBB
174 const Bitboard NeighboringFilesBB[8] = {
175 FileBBB, FileABB|FileCBB, FileBBB|FileDBB, FileCBB|FileEBB,
176 FileDBB|FileFBB, FileEBB|FileGBB, FileFBB|FileHBB, FileGBB
179 const Bitboard ThisAndNeighboringFilesBB[8] = {
180 FileABB|FileBBB, FileABB|FileBBB|FileCBB,
181 FileBBB|FileCBB|FileDBB, FileCBB|FileDBB|FileEBB,
182 FileDBB|FileEBB|FileFBB, FileEBB|FileFBB|FileGBB,
183 FileFBB|FileGBB|FileHBB, FileGBB|FileHBB
186 const Bitboard RankBB[8] = {
187 Rank1BB, Rank2BB, Rank3BB, Rank4BB, Rank5BB, Rank6BB, Rank7BB, Rank8BB
190 const Bitboard RelativeRankBB[2][8] = {
191 { Rank1BB, Rank2BB, Rank3BB, Rank4BB, Rank5BB, Rank6BB, Rank7BB, Rank8BB },
192 { Rank8BB, Rank7BB, Rank6BB, Rank5BB, Rank4BB, Rank3BB, Rank2BB, Rank1BB }
195 const Bitboard InFrontBB[2][8] = {
196 { Rank2BB | Rank3BB | Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB,
197 Rank3BB | Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB,
198 Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB,
199 Rank5BB | Rank6BB | Rank7BB | Rank8BB,
200 Rank6BB | Rank7BB | Rank8BB,
208 Rank3BB | Rank2BB | Rank1BB,
209 Rank4BB | Rank3BB | Rank2BB | Rank1BB,
210 Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB,
211 Rank6BB | Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB,
212 Rank7BB | Rank6BB | Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB
216 // Global bitboards definitions with static storage duration are
217 // automatically set to zero before enter main().
219 int RAttackIndex[64];
220 Bitboard RAttacks[0x19000];
223 int BAttackIndex[64];
224 Bitboard BAttacks[0x1480];
226 Bitboard SetMaskBB[65];
227 Bitboard ClearMaskBB[65];
229 Bitboard NonSlidingAttacksBB[16][64];
230 Bitboard BetweenBB[64][64];
232 Bitboard SquaresInFrontMask[2][64];
233 Bitboard PassedPawnMask[2][64];
234 Bitboard AttackSpanMask[2][64];
236 Bitboard BishopPseudoAttacks[64];
237 Bitboard RookPseudoAttacks[64];
238 Bitboard QueenPseudoAttacks[64];
240 uint8_t BitCount8Bit[256];
246 void init_non_sliding_attacks();
247 void init_pseudo_attacks();
248 void init_between_bitboards();
249 Bitboard index_to_bitboard(int index, Bitboard mask);
250 Bitboard sliding_attacks(int sq, Bitboard block, int dirs, int deltas[][2],
251 int fmin, int fmax, int rmin, int rmax);
252 void init_sliding_attacks(Bitboard attacks[], int attackIndex[], Bitboard mask[],
253 const int shift[], const Bitboard mult[], int deltas[][2]);
257 /// print_bitboard() prints a bitboard in an easily readable format to the
258 /// standard output. This is sometimes useful for debugging.
260 void print_bitboard(Bitboard b) {
262 for (Rank r = RANK_8; r >= RANK_1; r--)
264 std::cout << "+---+---+---+---+---+---+---+---+" << '\n';
265 for (File f = FILE_A; f <= FILE_H; f++)
266 std::cout << "| " << (bit_is_set(b, make_square(f, r))? 'X' : ' ') << ' ';
270 std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
274 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
275 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
276 /// nonzero bitboard.
278 #if defined(IS_64BIT) && !defined(USE_BSFQ)
280 static CACHE_LINE_ALIGNMENT
281 const int BitTable[64] = {
282 0, 1, 2, 7, 3, 13, 8, 19, 4, 25, 14, 28, 9, 34, 20, 40, 5, 17, 26, 38, 15,
283 46, 29, 48, 10, 31, 35, 54, 21, 50, 41, 57, 63, 6, 12, 18, 24, 27, 33, 39,
284 16, 37, 45, 47, 30, 53, 49, 56, 62, 11, 23, 32, 36, 44, 52, 55, 61, 22, 43,
288 Square first_1(Bitboard b) {
289 return Square(BitTable[((b & -b) * 0x218a392cd3d5dbfULL) >> 58]);
292 Square pop_1st_bit(Bitboard* b) {
295 return Square(BitTable[((bb & -bb) * 0x218a392cd3d5dbfULL) >> 58]);
298 #elif !defined(USE_BSFQ)
300 static CACHE_LINE_ALIGNMENT
301 const int BitTable[64] = {
302 63, 30, 3, 32, 25, 41, 22, 33, 15, 50, 42, 13, 11, 53, 19, 34, 61, 29, 2,
303 51, 21, 43, 45, 10, 18, 47, 1, 54, 9, 57, 0, 35, 62, 31, 40, 4, 49, 5, 52,
304 26, 60, 6, 23, 44, 46, 27, 56, 16, 7, 39, 48, 24, 59, 14, 12, 55, 38, 28,
305 58, 20, 37, 17, 36, 8
308 Square first_1(Bitboard b) {
311 uint32_t fold = int(b) ^ int(b >> 32);
312 return Square(BitTable[(fold * 0x783a9b23) >> 26]);
320 #if defined (BIGENDIAN)
330 Square pop_1st_bit(Bitboard* bb) {
339 ret = Square(BitTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783a9b23) >> 26]);
340 u.dw.l &= (u.dw.l - 1);
344 ret = Square(BitTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783a9b23) >> 26]);
345 u.dw.h &= (u.dw.h - 1);
353 /// init_bitboards() initializes various bitboard arrays. It is called during
354 /// program initialization.
356 void init_bitboards() {
358 int rookDeltas[4][2] = {{0,1},{0,-1},{1,0},{-1,0}};
359 int bishopDeltas[4][2] = {{1,1},{-1,1},{1,-1},{-1,-1}};
362 init_non_sliding_attacks();
363 init_sliding_attacks(RAttacks, RAttackIndex, RMask, RShift, RMult, rookDeltas);
364 init_sliding_attacks(BAttacks, BAttackIndex, BMask, BShift, BMult, bishopDeltas);
365 init_pseudo_attacks();
366 init_between_bitboards();
371 // All functions below are used to precompute various bitboards during
372 // program initialization. Some of the functions may be difficult to
373 // understand, but they all seem to work correctly, and it should never
374 // be necessary to touch any of them.
378 SetMaskBB[SQ_NONE] = EmptyBoardBB;
379 ClearMaskBB[SQ_NONE] = ~SetMaskBB[SQ_NONE];
381 for (Square s = SQ_A1; s <= SQ_H8; s++)
383 SetMaskBB[s] = (1ULL << s);
384 ClearMaskBB[s] = ~SetMaskBB[s];
387 for (Color c = WHITE; c <= BLACK; c++)
388 for (Square s = SQ_A1; s <= SQ_H8; s++)
390 SquaresInFrontMask[c][s] = in_front_bb(c, s) & file_bb(s);
391 PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s);
392 AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
395 for (Bitboard b = 0; b < 256; b++)
396 BitCount8Bit[b] = (uint8_t)count_1s<CNT32>(b);
399 void init_non_sliding_attacks() {
401 const int step[][9] = {
403 {7,9,0}, {17,15,10,6,-6,-10,-15,-17,0}, {0}, {0}, {0},
404 {9,7,-7,-9,8,1,-1,-8,0}, {0}, {0},
405 {-7,-9,0}, {17,15,10,6,-6,-10,-15,-17,0}, {0}, {0}, {0},
406 {9,7,-7,-9,8,1,-1,-8,0}
409 for (Square s = SQ_A1; s <= SQ_H8; s++)
410 for (Piece pc = WP; pc <= BK; pc++)
411 for (int k = 0; step[pc][k] != 0; k++)
413 Square to = s + Square(step[pc][k]);
415 if (square_is_ok(to) && square_distance(s, to) < 3)
416 set_bit(&NonSlidingAttacksBB[pc][s], to);
420 Bitboard sliding_attacks(int sq, Bitboard block, int dirs, int deltas[][2],
421 int fmin=0, int fmax=7, int rmin=0, int rmax=7) {
426 for (int i = 0; i < dirs; i++)
428 int dx = deltas[i][0];
429 int dy = deltas[i][1];
433 while ( (dx == 0 || (f >= fmin && f <= fmax))
434 && (dy == 0 || (r >= rmin && r <= rmax)))
436 result |= (1ULL << (f + r*8));
437 if (block & (1ULL << (f + r*8)))
447 Bitboard index_to_bitboard(int index, Bitboard mask) {
449 Bitboard result = EmptyBoardBB;
454 sq = pop_1st_bit(&mask);
456 if (index & (1 << cnt++))
457 result |= (1ULL << sq);
462 void init_sliding_attacks(Bitboard attacks[], int attackIndex[], Bitboard mask[],
463 const int shift[], const Bitboard mult[], int deltas[][2]) {
465 for (int i = 0, index = 0; i < 64; i++)
467 attackIndex[i] = index;
468 mask[i] = sliding_attacks(i, 0, 4, deltas, 1, 6, 1, 6);
470 #if defined(IS_64BIT)
471 int j = (1 << (64 - shift[i]));
473 int j = (1 << (32 - shift[i]));
476 for (int k = 0; k < j; k++)
478 #if defined(IS_64BIT)
479 Bitboard b = index_to_bitboard(k, mask[i]);
480 attacks[index + ((b * mult[i]) >> shift[i])] = sliding_attacks(i, b, 4, deltas);
482 Bitboard b = index_to_bitboard(k, mask[i]);
483 unsigned v = int(b) * int(mult[i]) ^ int(b >> 32) * int(mult[i] >> 32);
484 attacks[index + (v >> shift[i])] = sliding_attacks(i, b, 4, deltas);
491 void init_pseudo_attacks() {
493 for (Square s = SQ_A1; s <= SQ_H8; s++)
495 BishopPseudoAttacks[s] = bishop_attacks_bb(s, EmptyBoardBB);
496 RookPseudoAttacks[s] = rook_attacks_bb(s, EmptyBoardBB);
497 QueenPseudoAttacks[s] = queen_attacks_bb(s, EmptyBoardBB);
501 void init_between_bitboards() {
507 for (s1 = SQ_A1; s1 <= SQ_H8; s1++)
508 for (s2 = SQ_A1; s2 <= SQ_H8; s2++)
509 if (bit_is_set(QueenPseudoAttacks[s1], s2))
511 f = file_distance(s1, s2);
512 r = rank_distance(s1, s2);
514 d = SquareDelta(s2 - s1) / Max(f, r);
516 for (s3 = s1 + d; s3 != s2; s3 += d)
517 set_bit(&(BetweenBB[s1][s2]), s3);