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
217 int RAttackIndex[64];
218 Bitboard RAttacks[0x19000];
221 int BAttackIndex[64];
222 Bitboard BAttacks[0x1480];
224 Bitboard SetMaskBB[65];
225 Bitboard ClearMaskBB[65];
227 Bitboard StepAttackBB[16][64];
228 Bitboard BetweenBB[64][64];
230 Bitboard SquaresInFrontMask[2][64];
231 Bitboard PassedPawnMask[2][64];
232 Bitboard AttackSpanMask[2][64];
234 Bitboard BishopPseudoAttacks[64];
235 Bitboard RookPseudoAttacks[64];
236 Bitboard QueenPseudoAttacks[64];
238 uint8_t BitCount8Bit[256];
239 int8_t DirectionTable[64][64];
243 //// Local definitions
248 SquareDelta get_direction(Square orig, Square dest);
249 void init_direction_table();
252 void init_between_bitboards();
253 void init_pseudo_attacks();
254 Bitboard index_to_bitboard(int index, Bitboard mask);
255 Bitboard sliding_attacks(int sq, Bitboard block, int dirs, int deltas[][2],
256 int fmin, int fmax, int rmin, int rmax);
257 void init_sliding_attacks(Bitboard attacks[], int attackIndex[], Bitboard mask[],
258 const int shift[], const Bitboard mult[], int deltas[][2]);
266 /// print_bitboard() prints a bitboard in an easily readable format to the
267 /// standard output. This is sometimes useful for debugging.
269 void print_bitboard(Bitboard b) {
271 for (Rank r = RANK_8; r >= RANK_1; r--)
273 std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
274 for (File f = FILE_A; f <= FILE_H; f++)
275 std::cout << "| " << (bit_is_set(b, make_square(f, r))? 'X' : ' ') << ' ';
277 std::cout << "|" << std::endl;
279 std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
283 /// init_bitboards() initializes various bitboard arrays. It is called during
284 /// program initialization.
286 void init_bitboards() {
288 int rookDeltas[4][2] = {{0,1},{0,-1},{1,0},{-1,0}};
289 int bishopDeltas[4][2] = {{1,1},{-1,1},{1,-1},{-1,-1}};
291 init_direction_table();
294 init_between_bitboards();
295 init_sliding_attacks(RAttacks, RAttackIndex, RMask, RShift, RMult, rookDeltas);
296 init_sliding_attacks(BAttacks, BAttackIndex, BMask, BShift, BMult, bishopDeltas);
297 init_pseudo_attacks();
301 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
302 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
303 /// nonzero bitboard.
305 #if defined(IS_64BIT) && !defined(USE_BSFQ)
307 static CACHE_LINE_ALIGNMENT
308 const int BitTable[64] = {
309 0, 1, 2, 7, 3, 13, 8, 19, 4, 25, 14, 28, 9, 34, 20, 40, 5, 17, 26, 38, 15,
310 46, 29, 48, 10, 31, 35, 54, 21, 50, 41, 57, 63, 6, 12, 18, 24, 27, 33, 39,
311 16, 37, 45, 47, 30, 53, 49, 56, 62, 11, 23, 32, 36, 44, 52, 55, 61, 22, 43,
315 Square first_1(Bitboard b) {
316 return Square(BitTable[((b & -b) * 0x218a392cd3d5dbfULL) >> 58]);
319 Square pop_1st_bit(Bitboard* b) {
322 return Square(BitTable[((bb & -bb) * 0x218a392cd3d5dbfULL) >> 58]);
325 #elif !defined(USE_BSFQ)
327 static CACHE_LINE_ALIGNMENT
328 const int BitTable[64] = {
329 63, 30, 3, 32, 25, 41, 22, 33, 15, 50, 42, 13, 11, 53, 19, 34, 61, 29, 2,
330 51, 21, 43, 45, 10, 18, 47, 1, 54, 9, 57, 0, 35, 62, 31, 40, 4, 49, 5, 52,
331 26, 60, 6, 23, 44, 46, 27, 56, 16, 7, 39, 48, 24, 59, 14, 12, 55, 38, 28,
332 58, 20, 37, 17, 36, 8
335 Square first_1(Bitboard b) {
338 uint32_t fold = int(b) ^ int(b >> 32);
339 return Square(BitTable[(fold * 0x783a9b23) >> 26]);
347 #if defined (BIGENDIAN)
357 Square pop_1st_bit(Bitboard* bb) {
366 ret = Square(BitTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783a9b23) >> 26]);
367 u.dw.l &= (u.dw.l - 1);
371 ret = Square(BitTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783a9b23) >> 26]);
372 u.dw.h &= (u.dw.h - 1);
382 // All functions below are used to precompute various bitboards during
383 // program initialization. Some of the functions may be difficult to
384 // understand, but they all seem to work correctly, and it should never
385 // be necessary to touch any of them.
387 SquareDelta get_direction(Square orig, Square dest) {
389 const SquareDelta directions[] = {
390 DELTA_E, DELTA_N, DELTA_NE, DELTA_NW, DELTA_W, DELTA_S, DELTA_SW, DELTA_SE
393 for (int idx = 0; idx < 8; idx++)
396 Square to = from + directions[idx];
398 while (to != dest && square_distance(to, from) == 1 && square_is_ok(to))
401 to += directions[idx];
404 if (to == dest && square_distance(from, to) == 1)
405 return directions[idx];
410 void init_direction_table() {
412 for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
413 for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
414 DirectionTable[s1][s2] = uint8_t(get_direction(s1, s2));
419 SetMaskBB[SQ_NONE] = 0ULL;
420 ClearMaskBB[SQ_NONE] = ~SetMaskBB[SQ_NONE];
422 for (Square s = SQ_A1; s <= SQ_H8; s++)
424 SetMaskBB[s] = (1ULL << s);
425 ClearMaskBB[s] = ~SetMaskBB[s];
428 for (Color c = WHITE; c <= BLACK; c++)
429 for (Square s = SQ_A1; s <= SQ_H8; s++)
431 SquaresInFrontMask[c][s] = in_front_bb(c, s) & file_bb(s);
432 PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_neighboring_files_bb(s);
433 AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
436 for (Bitboard b = 0; b < 256; b++)
437 BitCount8Bit[b] = (uint8_t)count_1s<CNT32>(b);
440 void init_attacks() {
442 const int step[16][8] = {
444 {7,9,0}, {17,15,10,6,-6,-10,-15,-17}, {9,7,-7,-9,0}, {8,1,-1,-8,0},
445 {9,7,-7,-9,8,1,-1,-8}, {9,7,-7,-9,8,1,-1,-8}, {0}, {0},
446 {-7,-9,0}, {17,15,10,6,-6,-10,-15,-17}, {9,7,-7,-9,0}, {8,1,-1,-8,0},
447 {9,7,-7,-9,8,1,-1,-8}, {9,7,-7,-9,8,1,-1,-8}
450 for (int i = 0; i < 64; i++)
451 for (int j = 0; j <= int(BK); j++)
453 StepAttackBB[j][i] = EmptyBoardBB;
454 for (int k = 0; k < 8 && step[j][k] != 0; k++)
456 int l = i + step[j][k];
457 if (l >= 0 && l < 64 && abs((i & 7) - (l & 7)) < 3)
458 StepAttackBB[j][i] |= (1ULL << l);
463 Bitboard sliding_attacks(int sq, Bitboard block, int dirs, int deltas[][2],
464 int fmin=0, int fmax=7, int rmin=0, int rmax=7) {
465 Bitboard result = 0ULL;
469 for (int i = 0; i < dirs; i++)
471 int dx = deltas[i][0];
472 int dy = deltas[i][1];
476 while ( (dx == 0 || (f >= fmin && f <= fmax))
477 && (dy == 0 || (r >= rmin && r <= rmax)))
479 result |= (1ULL << (f + r*8));
480 if (block & (1ULL << (f + r*8)))
490 void init_between_bitboards() {
495 for (s1 = SQ_A1; s1 <= SQ_H8; s1++)
496 for (s2 = SQ_A1; s2 <= SQ_H8; s2++)
498 BetweenBB[s1][s2] = EmptyBoardBB;
499 d = SquareDelta(DirectionTable[s1][s2]);
504 for (s3 = s1 + d; s3 != s2; s3 += d)
505 set_bit(&(BetweenBB[s1][s2]), s3);
509 Bitboard index_to_bitboard(int index, Bitboard mask) {
511 Bitboard result = 0ULL;
512 int bits = count_1s<CNT32>(mask);
514 for (int i = 0; i < bits; i++)
516 int j = pop_1st_bit(&mask);
517 if (index & (1 << i))
518 result |= (1ULL << j);
523 void init_sliding_attacks(Bitboard attacks[], int attackIndex[], Bitboard mask[],
524 const int shift[], const Bitboard mult[], int deltas[][2]) {
526 for (int i = 0, index = 0; i < 64; i++)
528 attackIndex[i] = index;
529 mask[i] = sliding_attacks(i, 0, 4, deltas, 1, 6, 1, 6);
531 #if defined(IS_64BIT)
532 int j = (1 << (64 - shift[i]));
534 int j = (1 << (32 - shift[i]));
537 for (int k = 0; k < j; k++)
539 #if defined(IS_64BIT)
540 Bitboard b = index_to_bitboard(k, mask[i]);
541 attacks[index + ((b * mult[i]) >> shift[i])] = sliding_attacks(i, b, 4, deltas);
543 Bitboard b = index_to_bitboard(k, mask[i]);
544 unsigned v = int(b) * int(mult[i]) ^ int(b >> 32) * int(mult[i] >> 32);
545 attacks[index + (v >> shift[i])] = sliding_attacks(i, b, 4, deltas);
552 void init_pseudo_attacks() {
554 for (Square s = SQ_A1; s <= SQ_H8; s++)
556 BishopPseudoAttacks[s] = bishop_attacks_bb(s, EmptyBoardBB);
557 RookPseudoAttacks[s] = rook_attacks_bb(s, EmptyBoardBB);
558 QueenPseudoAttacks[s] = queen_attacks_bb(s, EmptyBoardBB);