Revert "Fix random moves when time < 10ms"
[stockfish] / src / book.cpp
1 /*
2   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4   Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
5
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.
10
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.
15
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/>.
18 */
19
20 /*
21   The code in this file is based on the opening book code in PolyGlot
22   by Fabien Letouzey. PolyGlot is available under the GNU General
23   Public License, and can be downloaded from http://wbec-ridderkerk.nl
24 */
25
26 #include <algorithm>
27 #include <cassert>
28 #include <iostream>
29
30 #include "book.h"
31 #include "misc.h"
32 #include "movegen.h"
33
34 using namespace std;
35
36 namespace {
37
38   // A Polyglot book is a series of "entries" of 16 bytes. All integers are
39   // stored in big-endian format, with highest byte first (regardless of size).
40   // The entries are ordered according to the key in ascending order.
41   struct Entry {
42     uint64_t key;
43     uint16_t move;
44     uint16_t count;
45     uint32_t learn;
46   };
47
48   // Random numbers from PolyGlot, used to compute book hash keys
49   const union {
50     Key PolyGlotRandoms[781];
51     struct {
52       Key psq[12][64];  // [piece][square]
53       Key castle[4];    // [castle right]
54       Key enpassant[8]; // [file]
55       Key turn;
56     } Zobrist;
57   } PG = {{
58     0x9D39247E33776D41ULL, 0x2AF7398005AAA5C7ULL, 0x44DB015024623547ULL,
59     0x9C15F73E62A76AE2ULL, 0x75834465489C0C89ULL, 0x3290AC3A203001BFULL,
60     0x0FBBAD1F61042279ULL, 0xE83A908FF2FB60CAULL, 0x0D7E765D58755C10ULL,
61     0x1A083822CEAFE02DULL, 0x9605D5F0E25EC3B0ULL, 0xD021FF5CD13A2ED5ULL,
62     0x40BDF15D4A672E32ULL, 0x011355146FD56395ULL, 0x5DB4832046F3D9E5ULL,
63     0x239F8B2D7FF719CCULL, 0x05D1A1AE85B49AA1ULL, 0x679F848F6E8FC971ULL,
64     0x7449BBFF801FED0BULL, 0x7D11CDB1C3B7ADF0ULL, 0x82C7709E781EB7CCULL,
65     0xF3218F1C9510786CULL, 0x331478F3AF51BBE6ULL, 0x4BB38DE5E7219443ULL,
66     0xAA649C6EBCFD50FCULL, 0x8DBD98A352AFD40BULL, 0x87D2074B81D79217ULL,
67     0x19F3C751D3E92AE1ULL, 0xB4AB30F062B19ABFULL, 0x7B0500AC42047AC4ULL,
68     0xC9452CA81A09D85DULL, 0x24AA6C514DA27500ULL, 0x4C9F34427501B447ULL,
69     0x14A68FD73C910841ULL, 0xA71B9B83461CBD93ULL, 0x03488B95B0F1850FULL,
70     0x637B2B34FF93C040ULL, 0x09D1BC9A3DD90A94ULL, 0x3575668334A1DD3BULL,
71     0x735E2B97A4C45A23ULL, 0x18727070F1BD400BULL, 0x1FCBACD259BF02E7ULL,
72     0xD310A7C2CE9B6555ULL, 0xBF983FE0FE5D8244ULL, 0x9F74D14F7454A824ULL,
73     0x51EBDC4AB9BA3035ULL, 0x5C82C505DB9AB0FAULL, 0xFCF7FE8A3430B241ULL,
74     0x3253A729B9BA3DDEULL, 0x8C74C368081B3075ULL, 0xB9BC6C87167C33E7ULL,
75     0x7EF48F2B83024E20ULL, 0x11D505D4C351BD7FULL, 0x6568FCA92C76A243ULL,
76     0x4DE0B0F40F32A7B8ULL, 0x96D693460CC37E5DULL, 0x42E240CB63689F2FULL,
77     0x6D2BDCDAE2919661ULL, 0x42880B0236E4D951ULL, 0x5F0F4A5898171BB6ULL,
78     0x39F890F579F92F88ULL, 0x93C5B5F47356388BULL, 0x63DC359D8D231B78ULL,
79     0xEC16CA8AEA98AD76ULL, 0x5355F900C2A82DC7ULL, 0x07FB9F855A997142ULL,
80     0x5093417AA8A7ED5EULL, 0x7BCBC38DA25A7F3CULL, 0x19FC8A768CF4B6D4ULL,
81     0x637A7780DECFC0D9ULL, 0x8249A47AEE0E41F7ULL, 0x79AD695501E7D1E8ULL,
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83     0x24C3C94DF9C8D3F6ULL, 0xBB6E2924F03912EAULL, 0x0CE26C0B95C980D9ULL,
84     0xA49CD132BFBF7CC4ULL, 0xE99D662AF4243939ULL, 0x27E6AD7891165C3FULL,
85     0x8535F040B9744FF1ULL, 0x54B3F4FA5F40D873ULL, 0x72B12C32127FED2BULL,
86     0xEE954D3C7B411F47ULL, 0x9A85AC909A24EAA1ULL, 0x70AC4CD9F04F21F5ULL,
87     0xF9B89D3E99A075C2ULL, 0x87B3E2B2B5C907B1ULL, 0xA366E5B8C54F48B8ULL,
88     0xAE4A9346CC3F7CF2ULL, 0x1920C04D47267BBDULL, 0x87BF02C6B49E2AE9ULL,
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90     0x9C1633264DB49C89ULL, 0xB3F22C3D0B0B38EDULL, 0x390E5FB44D01144BULL,
91     0x5BFEA5B4712768E9ULL, 0x1E1032911FA78984ULL, 0x9A74ACB964E78CB3ULL,
92     0x4F80F7A035DAFB04ULL, 0x6304D09A0B3738C4ULL, 0x2171E64683023A08ULL,
93     0x5B9B63EB9CEFF80CULL, 0x506AACF489889342ULL, 0x1881AFC9A3A701D6ULL,
94     0x6503080440750644ULL, 0xDFD395339CDBF4A7ULL, 0xEF927DBCF00C20F2ULL,
95     0x7B32F7D1E03680ECULL, 0xB9FD7620E7316243ULL, 0x05A7E8A57DB91B77ULL,
96     0xB5889C6E15630A75ULL, 0x4A750A09CE9573F7ULL, 0xCF464CEC899A2F8AULL,
97     0xF538639CE705B824ULL, 0x3C79A0FF5580EF7FULL, 0xEDE6C87F8477609DULL,
98     0x799E81F05BC93F31ULL, 0x86536B8CF3428A8CULL, 0x97D7374C60087B73ULL,
99     0xA246637CFF328532ULL, 0x043FCAE60CC0EBA0ULL, 0x920E449535DD359EULL,
100     0x70EB093B15B290CCULL, 0x73A1921916591CBDULL, 0x56436C9FE1A1AA8DULL,
101     0xEFAC4B70633B8F81ULL, 0xBB215798D45DF7AFULL, 0x45F20042F24F1768ULL,
102     0x930F80F4E8EB7462ULL, 0xFF6712FFCFD75EA1ULL, 0xAE623FD67468AA70ULL,
103     0xDD2C5BC84BC8D8FCULL, 0x7EED120D54CF2DD9ULL, 0x22FE545401165F1CULL,
104     0xC91800E98FB99929ULL, 0x808BD68E6AC10365ULL, 0xDEC468145B7605F6ULL,
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106     0xA87832D392EFEE56ULL, 0x65942C7B3C7E11AEULL, 0xDED2D633CAD004F6ULL,
107     0x21F08570F420E565ULL, 0xB415938D7DA94E3CULL, 0x91B859E59ECB6350ULL,
108     0x10CFF333E0ED804AULL, 0x28AED140BE0BB7DDULL, 0xC5CC1D89724FA456ULL,
109     0x5648F680F11A2741ULL, 0x2D255069F0B7DAB3ULL, 0x9BC5A38EF729ABD4ULL,
110     0xEF2F054308F6A2BCULL, 0xAF2042F5CC5C2858ULL, 0x480412BAB7F5BE2AULL,
111     0xAEF3AF4A563DFE43ULL, 0x19AFE59AE451497FULL, 0x52593803DFF1E840ULL,
112     0xF4F076E65F2CE6F0ULL, 0x11379625747D5AF3ULL, 0xBCE5D2248682C115ULL,
113     0x9DA4243DE836994FULL, 0x066F70B33FE09017ULL, 0x4DC4DE189B671A1CULL,
114     0x51039AB7712457C3ULL, 0xC07A3F80C31FB4B4ULL, 0xB46EE9C5E64A6E7CULL,
115     0xB3819A42ABE61C87ULL, 0x21A007933A522A20ULL, 0x2DF16F761598AA4FULL,
116     0x763C4A1371B368FDULL, 0xF793C46702E086A0ULL, 0xD7288E012AEB8D31ULL,
117     0xDE336A2A4BC1C44BULL, 0x0BF692B38D079F23ULL, 0x2C604A7A177326B3ULL,
118     0x4850E73E03EB6064ULL, 0xCFC447F1E53C8E1BULL, 0xB05CA3F564268D99ULL,
119     0x9AE182C8BC9474E8ULL, 0xA4FC4BD4FC5558CAULL, 0xE755178D58FC4E76ULL,
120     0x69B97DB1A4C03DFEULL, 0xF9B5B7C4ACC67C96ULL, 0xFC6A82D64B8655FBULL,
121     0x9C684CB6C4D24417ULL, 0x8EC97D2917456ED0ULL, 0x6703DF9D2924E97EULL,
122     0xC547F57E42A7444EULL, 0x78E37644E7CAD29EULL, 0xFE9A44E9362F05FAULL,
123     0x08BD35CC38336615ULL, 0x9315E5EB3A129ACEULL, 0x94061B871E04DF75ULL,
124     0xDF1D9F9D784BA010ULL, 0x3BBA57B68871B59DULL, 0xD2B7ADEEDED1F73FULL,
125     0xF7A255D83BC373F8ULL, 0xD7F4F2448C0CEB81ULL, 0xD95BE88CD210FFA7ULL,
126     0x336F52F8FF4728E7ULL, 0xA74049DAC312AC71ULL, 0xA2F61BB6E437FDB5ULL,
127     0x4F2A5CB07F6A35B3ULL, 0x87D380BDA5BF7859ULL, 0x16B9F7E06C453A21ULL,
128     0x7BA2484C8A0FD54EULL, 0xF3A678CAD9A2E38CULL, 0x39B0BF7DDE437BA2ULL,
129     0xFCAF55C1BF8A4424ULL, 0x18FCF680573FA594ULL, 0x4C0563B89F495AC3ULL,
130     0x40E087931A00930DULL, 0x8CFFA9412EB642C1ULL, 0x68CA39053261169FULL,
131     0x7A1EE967D27579E2ULL, 0x9D1D60E5076F5B6FULL, 0x3810E399B6F65BA2ULL,
132     0x32095B6D4AB5F9B1ULL, 0x35CAB62109DD038AULL, 0xA90B24499FCFAFB1ULL,
133     0x77A225A07CC2C6BDULL, 0x513E5E634C70E331ULL, 0x4361C0CA3F692F12ULL,
134     0xD941ACA44B20A45BULL, 0x528F7C8602C5807BULL, 0x52AB92BEB9613989ULL,
135     0x9D1DFA2EFC557F73ULL, 0x722FF175F572C348ULL, 0x1D1260A51107FE97ULL,
136     0x7A249A57EC0C9BA2ULL, 0x04208FE9E8F7F2D6ULL, 0x5A110C6058B920A0ULL,
137     0x0CD9A497658A5698ULL, 0x56FD23C8F9715A4CULL, 0x284C847B9D887AAEULL,
138     0x04FEABFBBDB619CBULL, 0x742E1E651C60BA83ULL, 0x9A9632E65904AD3CULL,
139     0x881B82A13B51B9E2ULL, 0x506E6744CD974924ULL, 0xB0183DB56FFC6A79ULL,
140     0x0ED9B915C66ED37EULL, 0x5E11E86D5873D484ULL, 0xF678647E3519AC6EULL,
141     0x1B85D488D0F20CC5ULL, 0xDAB9FE6525D89021ULL, 0x0D151D86ADB73615ULL,
142     0xA865A54EDCC0F019ULL, 0x93C42566AEF98FFBULL, 0x99E7AFEABE000731ULL,
143     0x48CBFF086DDF285AULL, 0x7F9B6AF1EBF78BAFULL, 0x58627E1A149BBA21ULL,
144     0x2CD16E2ABD791E33ULL, 0xD363EFF5F0977996ULL, 0x0CE2A38C344A6EEDULL,
145     0x1A804AADB9CFA741ULL, 0x907F30421D78C5DEULL, 0x501F65EDB3034D07ULL,
146     0x37624AE5A48FA6E9ULL, 0x957BAF61700CFF4EULL, 0x3A6C27934E31188AULL,
147     0xD49503536ABCA345ULL, 0x088E049589C432E0ULL, 0xF943AEE7FEBF21B8ULL,
148     0x6C3B8E3E336139D3ULL, 0x364F6FFA464EE52EULL, 0xD60F6DCEDC314222ULL,
149     0x56963B0DCA418FC0ULL, 0x16F50EDF91E513AFULL, 0xEF1955914B609F93ULL,
150     0x565601C0364E3228ULL, 0xECB53939887E8175ULL, 0xBAC7A9A18531294BULL,
151     0xB344C470397BBA52ULL, 0x65D34954DAF3CEBDULL, 0xB4B81B3FA97511E2ULL,
152     0xB422061193D6F6A7ULL, 0x071582401C38434DULL, 0x7A13F18BBEDC4FF5ULL,
153     0xBC4097B116C524D2ULL, 0x59B97885E2F2EA28ULL, 0x99170A5DC3115544ULL,
154     0x6F423357E7C6A9F9ULL, 0x325928EE6E6F8794ULL, 0xD0E4366228B03343ULL,
155     0x565C31F7DE89EA27ULL, 0x30F5611484119414ULL, 0xD873DB391292ED4FULL,
156     0x7BD94E1D8E17DEBCULL, 0xC7D9F16864A76E94ULL, 0x947AE053EE56E63CULL,
157     0xC8C93882F9475F5FULL, 0x3A9BF55BA91F81CAULL, 0xD9A11FBB3D9808E4ULL,
158     0x0FD22063EDC29FCAULL, 0xB3F256D8ACA0B0B9ULL, 0xB03031A8B4516E84ULL,
159     0x35DD37D5871448AFULL, 0xE9F6082B05542E4EULL, 0xEBFAFA33D7254B59ULL,
160     0x9255ABB50D532280ULL, 0xB9AB4CE57F2D34F3ULL, 0x693501D628297551ULL,
161     0xC62C58F97DD949BFULL, 0xCD454F8F19C5126AULL, 0xBBE83F4ECC2BDECBULL,
162     0xDC842B7E2819E230ULL, 0xBA89142E007503B8ULL, 0xA3BC941D0A5061CBULL,
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164     0x8107FCCF064FCF56ULL, 0x098954D51FFF6580ULL, 0x23B70EDB1955C4BFULL,
165     0xC330DE426430F69DULL, 0x4715ED43E8A45C0AULL, 0xA8D7E4DAB780A08DULL,
166     0x0572B974F03CE0BBULL, 0xB57D2E985E1419C7ULL, 0xE8D9ECBE2CF3D73FULL,
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171     0x18A6A990C8B35EBDULL, 0xCCCB7005C6B9C28DULL, 0x3BDBB92C43B17F26ULL,
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204     0x2C5E9DEB57EF4743ULL, 0x3A938FEE32D29981ULL, 0x26E6DB8FFDF5ADFEULL,
205     0x469356C504EC9F9DULL, 0xC8763C5B08D1908CULL, 0x3F6C6AF859D80055ULL,
206     0x7F7CC39420A3A545ULL, 0x9BFB227EBDF4C5CEULL, 0x89039D79D6FC5C5CULL,
207     0x8FE88B57305E2AB6ULL, 0xA09E8C8C35AB96DEULL, 0xFA7E393983325753ULL,
208     0xD6B6D0ECC617C699ULL, 0xDFEA21EA9E7557E3ULL, 0xB67C1FA481680AF8ULL,
209     0xCA1E3785A9E724E5ULL, 0x1CFC8BED0D681639ULL, 0xD18D8549D140CAEAULL,
210     0x4ED0FE7E9DC91335ULL, 0xE4DBF0634473F5D2ULL, 0x1761F93A44D5AEFEULL,
211     0x53898E4C3910DA55ULL, 0x734DE8181F6EC39AULL, 0x2680B122BAA28D97ULL,
212     0x298AF231C85BAFABULL, 0x7983EED3740847D5ULL, 0x66C1A2A1A60CD889ULL,
213     0x9E17E49642A3E4C1ULL, 0xEDB454E7BADC0805ULL, 0x50B704CAB602C329ULL,
214     0x4CC317FB9CDDD023ULL, 0x66B4835D9EAFEA22ULL, 0x219B97E26FFC81BDULL,
215     0x261E4E4C0A333A9DULL, 0x1FE2CCA76517DB90ULL, 0xD7504DFA8816EDBBULL,
216     0xB9571FA04DC089C8ULL, 0x1DDC0325259B27DEULL, 0xCF3F4688801EB9AAULL,
217     0xF4F5D05C10CAB243ULL, 0x38B6525C21A42B0EULL, 0x36F60E2BA4FA6800ULL,
218     0xEB3593803173E0CEULL, 0x9C4CD6257C5A3603ULL, 0xAF0C317D32ADAA8AULL,
219     0x258E5A80C7204C4BULL, 0x8B889D624D44885DULL, 0xF4D14597E660F855ULL,
220     0xD4347F66EC8941C3ULL, 0xE699ED85B0DFB40DULL, 0x2472F6207C2D0484ULL,
221     0xC2A1E7B5B459AEB5ULL, 0xAB4F6451CC1D45ECULL, 0x63767572AE3D6174ULL,
222     0xA59E0BD101731A28ULL, 0x116D0016CB948F09ULL, 0x2CF9C8CA052F6E9FULL,
223     0x0B090A7560A968E3ULL, 0xABEEDDB2DDE06FF1ULL, 0x58EFC10B06A2068DULL,
224     0xC6E57A78FBD986E0ULL, 0x2EAB8CA63CE802D7ULL, 0x14A195640116F336ULL,
225     0x7C0828DD624EC390ULL, 0xD74BBE77E6116AC7ULL, 0x804456AF10F5FB53ULL,
226     0xEBE9EA2ADF4321C7ULL, 0x03219A39EE587A30ULL, 0x49787FEF17AF9924ULL,
227     0xA1E9300CD8520548ULL, 0x5B45E522E4B1B4EFULL, 0xB49C3B3995091A36ULL,
228     0xD4490AD526F14431ULL, 0x12A8F216AF9418C2ULL, 0x001F837CC7350524ULL,
229     0x1877B51E57A764D5ULL, 0xA2853B80F17F58EEULL, 0x993E1DE72D36D310ULL,
230     0xB3598080CE64A656ULL, 0x252F59CF0D9F04BBULL, 0xD23C8E176D113600ULL,
231     0x1BDA0492E7E4586EULL, 0x21E0BD5026C619BFULL, 0x3B097ADAF088F94EULL,
232     0x8D14DEDB30BE846EULL, 0xF95CFFA23AF5F6F4ULL, 0x3871700761B3F743ULL,
233     0xCA672B91E9E4FA16ULL, 0x64C8E531BFF53B55ULL, 0x241260ED4AD1E87DULL,
234     0x106C09B972D2E822ULL, 0x7FBA195410E5CA30ULL, 0x7884D9BC6CB569D8ULL,
235     0x0647DFEDCD894A29ULL, 0x63573FF03E224774ULL, 0x4FC8E9560F91B123ULL,
236     0x1DB956E450275779ULL, 0xB8D91274B9E9D4FBULL, 0xA2EBEE47E2FBFCE1ULL,
237     0xD9F1F30CCD97FB09ULL, 0xEFED53D75FD64E6BULL, 0x2E6D02C36017F67FULL,
238     0xA9AA4D20DB084E9BULL, 0xB64BE8D8B25396C1ULL, 0x70CB6AF7C2D5BCF0ULL,
239     0x98F076A4F7A2322EULL, 0xBF84470805E69B5FULL, 0x94C3251F06F90CF3ULL,
240     0x3E003E616A6591E9ULL, 0xB925A6CD0421AFF3ULL, 0x61BDD1307C66E300ULL,
241     0xBF8D5108E27E0D48ULL, 0x240AB57A8B888B20ULL, 0xFC87614BAF287E07ULL,
242     0xEF02CDD06FFDB432ULL, 0xA1082C0466DF6C0AULL, 0x8215E577001332C8ULL,
243     0xD39BB9C3A48DB6CFULL, 0x2738259634305C14ULL, 0x61CF4F94C97DF93DULL,
244     0x1B6BACA2AE4E125BULL, 0x758F450C88572E0BULL, 0x959F587D507A8359ULL,
245     0xB063E962E045F54DULL, 0x60E8ED72C0DFF5D1ULL, 0x7B64978555326F9FULL,
246     0xFD080D236DA814BAULL, 0x8C90FD9B083F4558ULL, 0x106F72FE81E2C590ULL,
247     0x7976033A39F7D952ULL, 0xA4EC0132764CA04BULL, 0x733EA705FAE4FA77ULL,
248     0xB4D8F77BC3E56167ULL, 0x9E21F4F903B33FD9ULL, 0x9D765E419FB69F6DULL,
249     0xD30C088BA61EA5EFULL, 0x5D94337FBFAF7F5BULL, 0x1A4E4822EB4D7A59ULL,
250     0x6FFE73E81B637FB3ULL, 0xDDF957BC36D8B9CAULL, 0x64D0E29EEA8838B3ULL,
251     0x08DD9BDFD96B9F63ULL, 0x087E79E5A57D1D13ULL, 0xE328E230E3E2B3FBULL,
252     0x1C2559E30F0946BEULL, 0x720BF5F26F4D2EAAULL, 0xB0774D261CC609DBULL,
253     0x443F64EC5A371195ULL, 0x4112CF68649A260EULL, 0xD813F2FAB7F5C5CAULL,
254     0x660D3257380841EEULL, 0x59AC2C7873F910A3ULL, 0xE846963877671A17ULL,
255     0x93B633ABFA3469F8ULL, 0xC0C0F5A60EF4CDCFULL, 0xCAF21ECD4377B28CULL,
256     0x57277707199B8175ULL, 0x506C11B9D90E8B1DULL, 0xD83CC2687A19255FULL,
257     0x4A29C6465A314CD1ULL, 0xED2DF21216235097ULL, 0xB5635C95FF7296E2ULL,
258     0x22AF003AB672E811ULL, 0x52E762596BF68235ULL, 0x9AEBA33AC6ECC6B0ULL,
259     0x944F6DE09134DFB6ULL, 0x6C47BEC883A7DE39ULL, 0x6AD047C430A12104ULL,
260     0xA5B1CFDBA0AB4067ULL, 0x7C45D833AFF07862ULL, 0x5092EF950A16DA0BULL,
261     0x9338E69C052B8E7BULL, 0x455A4B4CFE30E3F5ULL, 0x6B02E63195AD0CF8ULL,
262     0x6B17B224BAD6BF27ULL, 0xD1E0CCD25BB9C169ULL, 0xDE0C89A556B9AE70ULL,
263     0x50065E535A213CF6ULL, 0x9C1169FA2777B874ULL, 0x78EDEFD694AF1EEDULL,
264     0x6DC93D9526A50E68ULL, 0xEE97F453F06791EDULL, 0x32AB0EDB696703D3ULL,
265     0x3A6853C7E70757A7ULL, 0x31865CED6120F37DULL, 0x67FEF95D92607890ULL,
266     0x1F2B1D1F15F6DC9CULL, 0xB69E38A8965C6B65ULL, 0xAA9119FF184CCCF4ULL,
267     0xF43C732873F24C13ULL, 0xFB4A3D794A9A80D2ULL, 0x3550C2321FD6109CULL,
268     0x371F77E76BB8417EULL, 0x6BFA9AAE5EC05779ULL, 0xCD04F3FF001A4778ULL,
269     0xE3273522064480CAULL, 0x9F91508BFFCFC14AULL, 0x049A7F41061A9E60ULL,
270     0xFCB6BE43A9F2FE9BULL, 0x08DE8A1C7797DA9BULL, 0x8F9887E6078735A1ULL,
271     0xB5B4071DBFC73A66ULL, 0x230E343DFBA08D33ULL, 0x43ED7F5A0FAE657DULL,
272     0x3A88A0FBBCB05C63ULL, 0x21874B8B4D2DBC4FULL, 0x1BDEA12E35F6A8C9ULL,
273     0x53C065C6C8E63528ULL, 0xE34A1D250E7A8D6BULL, 0xD6B04D3B7651DD7EULL,
274     0x5E90277E7CB39E2DULL, 0x2C046F22062DC67DULL, 0xB10BB459132D0A26ULL,
275     0x3FA9DDFB67E2F199ULL, 0x0E09B88E1914F7AFULL, 0x10E8B35AF3EEAB37ULL,
276     0x9EEDECA8E272B933ULL, 0xD4C718BC4AE8AE5FULL, 0x81536D601170FC20ULL,
277     0x91B534F885818A06ULL, 0xEC8177F83F900978ULL, 0x190E714FADA5156EULL,
278     0xB592BF39B0364963ULL, 0x89C350C893AE7DC1ULL, 0xAC042E70F8B383F2ULL,
279     0xB49B52E587A1EE60ULL, 0xFB152FE3FF26DA89ULL, 0x3E666E6F69AE2C15ULL,
280     0x3B544EBE544C19F9ULL, 0xE805A1E290CF2456ULL, 0x24B33C9D7ED25117ULL,
281     0xE74733427B72F0C1ULL, 0x0A804D18B7097475ULL, 0x57E3306D881EDB4FULL,
282     0x4AE7D6A36EB5DBCBULL, 0x2D8D5432157064C8ULL, 0xD1E649DE1E7F268BULL,
283     0x8A328A1CEDFE552CULL, 0x07A3AEC79624C7DAULL, 0x84547DDC3E203C94ULL,
284     0x990A98FD5071D263ULL, 0x1A4FF12616EEFC89ULL, 0xF6F7FD1431714200ULL,
285     0x30C05B1BA332F41CULL, 0x8D2636B81555A786ULL, 0x46C9FEB55D120902ULL,
286     0xCCEC0A73B49C9921ULL, 0x4E9D2827355FC492ULL, 0x19EBB029435DCB0FULL,
287     0x4659D2B743848A2CULL, 0x963EF2C96B33BE31ULL, 0x74F85198B05A2E7DULL,
288     0x5A0F544DD2B1FB18ULL, 0x03727073C2E134B1ULL, 0xC7F6AA2DE59AEA61ULL,
289     0x352787BAA0D7C22FULL, 0x9853EAB63B5E0B35ULL, 0xABBDCDD7ED5C0860ULL,
290     0xCF05DAF5AC8D77B0ULL, 0x49CAD48CEBF4A71EULL, 0x7A4C10EC2158C4A6ULL,
291     0xD9E92AA246BF719EULL, 0x13AE978D09FE5557ULL, 0x730499AF921549FFULL,
292     0x4E4B705B92903BA4ULL, 0xFF577222C14F0A3AULL, 0x55B6344CF97AAFAEULL,
293     0xB862225B055B6960ULL, 0xCAC09AFBDDD2CDB4ULL, 0xDAF8E9829FE96B5FULL,
294     0xB5FDFC5D3132C498ULL, 0x310CB380DB6F7503ULL, 0xE87FBB46217A360EULL,
295     0x2102AE466EBB1148ULL, 0xF8549E1A3AA5E00DULL, 0x07A69AFDCC42261AULL,
296     0xC4C118BFE78FEAAEULL, 0xF9F4892ED96BD438ULL, 0x1AF3DBE25D8F45DAULL,
297     0xF5B4B0B0D2DEEEB4ULL, 0x962ACEEFA82E1C84ULL, 0x046E3ECAAF453CE9ULL,
298     0xF05D129681949A4CULL, 0x964781CE734B3C84ULL, 0x9C2ED44081CE5FBDULL,
299     0x522E23F3925E319EULL, 0x177E00F9FC32F791ULL, 0x2BC60A63A6F3B3F2ULL,
300     0x222BBFAE61725606ULL, 0x486289DDCC3D6780ULL, 0x7DC7785B8EFDFC80ULL,
301     0x8AF38731C02BA980ULL, 0x1FAB64EA29A2DDF7ULL, 0xE4D9429322CD065AULL,
302     0x9DA058C67844F20CULL, 0x24C0E332B70019B0ULL, 0x233003B5A6CFE6ADULL,
303     0xD586BD01C5C217F6ULL, 0x5E5637885F29BC2BULL, 0x7EBA726D8C94094BULL,
304     0x0A56A5F0BFE39272ULL, 0xD79476A84EE20D06ULL, 0x9E4C1269BAA4BF37ULL,
305     0x17EFEE45B0DEE640ULL, 0x1D95B0A5FCF90BC6ULL, 0x93CBE0B699C2585DULL,
306     0x65FA4F227A2B6D79ULL, 0xD5F9E858292504D5ULL, 0xC2B5A03F71471A6FULL,
307     0x59300222B4561E00ULL, 0xCE2F8642CA0712DCULL, 0x7CA9723FBB2E8988ULL,
308     0x2785338347F2BA08ULL, 0xC61BB3A141E50E8CULL, 0x150F361DAB9DEC26ULL,
309     0x9F6A419D382595F4ULL, 0x64A53DC924FE7AC9ULL, 0x142DE49FFF7A7C3DULL,
310     0x0C335248857FA9E7ULL, 0x0A9C32D5EAE45305ULL, 0xE6C42178C4BBB92EULL,
311     0x71F1CE2490D20B07ULL, 0xF1BCC3D275AFE51AULL, 0xE728E8C83C334074ULL,
312     0x96FBF83A12884624ULL, 0x81A1549FD6573DA5ULL, 0x5FA7867CAF35E149ULL,
313     0x56986E2EF3ED091BULL, 0x917F1DD5F8886C61ULL, 0xD20D8C88C8FFE65FULL,
314     0x31D71DCE64B2C310ULL, 0xF165B587DF898190ULL, 0xA57E6339DD2CF3A0ULL,
315     0x1EF6E6DBB1961EC9ULL, 0x70CC73D90BC26E24ULL, 0xE21A6B35DF0C3AD7ULL,
316     0x003A93D8B2806962ULL, 0x1C99DED33CB890A1ULL, 0xCF3145DE0ADD4289ULL,
317     0xD0E4427A5514FB72ULL, 0x77C621CC9FB3A483ULL, 0x67A34DAC4356550BULL,
318     0xF8D626AAAF278509ULL
319   }};
320
321   // polyglot_key() returns the PolyGlot hash key of the given position
322   Key polyglot_key(const Position& pos) {
323
324     Key key = 0;
325     Bitboard b = pos.pieces();
326
327     while (b)
328     {
329         Square s = pop_lsb(&b);
330         Piece p = pos.piece_on(s);
331
332         // PolyGlot pieces are: BP = 0, WP = 1, BN = 2, ... BK = 10, WK = 11
333         key ^= PG.Zobrist.psq[2 * (type_of(p) - 1) + (color_of(p) == WHITE)][s];
334     }
335
336     b = pos.can_castle(ALL_CASTLES);
337
338     while (b)
339         key ^= PG.Zobrist.castle[pop_lsb(&b)];
340
341     if (pos.ep_square() != SQ_NONE)
342         key ^= PG.Zobrist.enpassant[file_of(pos.ep_square())];
343
344     if (pos.side_to_move() == WHITE)
345         key ^= PG.Zobrist.turn;
346
347     return key;
348   }
349
350 } // namespace
351
352 PolyglotBook::PolyglotBook() : rkiss(Time::now() % 10000) {}
353
354 PolyglotBook::~PolyglotBook() { if (is_open()) close(); }
355
356
357 /// operator>>() reads sizeof(T) chars from the file's binary byte stream and
358 /// converts them in a number of type T. A Polyglot book stores numbers in
359 /// big-endian format.
360
361 template<typename T> PolyglotBook& PolyglotBook::operator>>(T& n) {
362
363   n = 0;
364   for (size_t i = 0; i < sizeof(T); i++)
365       n = T((n << 8) + ifstream::get());
366
367   return *this;
368 }
369
370 template<> PolyglotBook& PolyglotBook::operator>>(Entry& e) {
371   return *this >> e.key >> e.move >> e.count >> e.learn;
372 }
373
374
375 /// open() tries to open a book file with the given name after closing any
376 /// exsisting one.
377
378 bool PolyglotBook::open(const char* fName) {
379
380   if (is_open()) // Cannot close an already closed file
381       close();
382
383   ifstream::open(fName, ifstream::in | ifstream::binary);
384
385   fileName = is_open() ? fName : "";
386   ifstream::clear(); // Reset any error flag to allow retry ifstream::open()
387   return !fileName.empty();
388 }
389
390
391 /// probe() tries to find a book move for the given position. If no move is
392 /// found returns MOVE_NONE. If pickBest is true returns always the highest
393 /// rated move, otherwise randomly chooses one, based on the move score.
394
395 Move PolyglotBook::probe(const Position& pos, const string& fName, bool pickBest) {
396
397   if (fileName != fName && !open(fName.c_str()))
398       return MOVE_NONE;
399
400   Entry e;
401   uint16_t best = 0;
402   unsigned sum = 0;
403   Move move = MOVE_NONE;
404   Key key = polyglot_key(pos);
405
406   seekg(find_first(key) * sizeof(Entry), ios_base::beg);
407
408   while (*this >> e, e.key == key && good())
409   {
410       best = max(best, e.count);
411       sum += e.count;
412
413       // Choose book move according to its score. If a move has a very
414       // high score it has higher probability to be choosen than a move
415       // with lower score. Note that first entry is always chosen.
416       if (   (sum && rkiss.rand<unsigned>() % sum < e.count)
417           || (pickBest && e.count == best))
418           move = Move(e.move);
419   }
420
421   if (!move)
422       return MOVE_NONE;
423
424   // A PolyGlot book move is encoded as follows:
425   //
426   // bit  0- 5: destination square (from 0 to 63)
427   // bit  6-11: origin square (from 0 to 63)
428   // bit 12-14: promotion piece (from KNIGHT == 1 to QUEEN == 4)
429   //
430   // Castling moves follow "king captures rook" representation. So in case book
431   // move is a promotion we have to convert to our representation, in all the
432   // other cases we can directly compare with a Move after having masked out
433   // the special Move's flags (bit 14-15) that are not supported by PolyGlot.
434   int pt = (move >> 12) & 7;
435   if (pt)
436       move = make<PROMOTION>(from_sq(move), to_sq(move), PieceType(pt + 1));
437
438   // Add 'special move' flags and verify it is legal
439   for (MoveList<LEGAL> it(pos); *it; ++it)
440       if (move == (*it ^ type_of(*it)))
441           return *it;
442
443   return MOVE_NONE;
444 }
445
446
447 /// find_first() takes a book key as input, and does a binary search through
448 /// the book file for the given key. Returns the index of the leftmost book
449 /// entry with the same key as the input.
450
451 size_t PolyglotBook::find_first(Key key) {
452
453   seekg(0, ios::end); // Move pointer to end, so tellg() gets file's size
454
455   size_t low = 0, mid, high = (size_t)tellg() / sizeof(Entry) - 1;
456   Entry e;
457
458   assert(low <= high);
459
460   while (low < high && good())
461   {
462       mid = (low + high) / 2;
463
464       assert(mid >= low && mid < high);
465
466       seekg(mid * sizeof(Entry), ios_base::beg);
467       *this >> e;
468
469       if (key <= e.key)
470           high = mid;
471       else
472           low = mid + 1;
473   }
474
475   assert(low == high);
476
477   return low;
478 }