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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 99 | pmbaty | 1 | /* |
| 2 | Texel - A UCI chess engine. |
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| 3 | Copyright (C) 2012-2013 Peter Österlund, peterosterlund2@gmail.com |
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| 4 | |||
| 5 | This program is free software: you can redistribute it and/or modify |
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| 6 | it under the terms of the GNU General Public License as published by |
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| 7 | the Free Software Foundation, either version 3 of the License, or |
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| 8 | (at your option) any later version. |
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| 9 | |||
| 10 | This program is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 13 | GNU General Public License for more details. |
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| 14 | |||
| 15 | You should have received a copy of the GNU General Public License |
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| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>. |
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| 17 | */ |
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| 18 | |||
| 19 | /* |
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| 20 | * history.hpp |
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| 21 | * |
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| 22 | * Created on: Feb 25, 2012 |
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| 23 | * Author: petero |
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| 24 | */ |
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| 25 | |||
| 26 | #ifndef HISTORY_HPP_ |
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| 27 | #define HISTORY_HPP_ |
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| 28 | |||
| 29 | #include "piece.hpp" |
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| 30 | #include "position.hpp" |
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| 31 | |||
| 32 | /** |
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| 33 | * Implements the relative history heuristic. |
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| 34 | */ |
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| 35 | class History { |
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| 36 | public: |
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| 37 | History(); |
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| 38 | |||
| 39 | /** Clear all history information. */ |
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| 40 | void init(); |
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| 41 | |||
| 42 | /** Rescale the history counters, so that future updates have more weight. */ |
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| 43 | void reScale(); |
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| 44 | |||
| 45 | /** Record move as a success. */ |
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| 46 | void addSuccess(const Position& pos, const Move& m, int depth); |
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| 47 | |||
| 48 | /** Record move as a failure. */ |
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| 49 | void addFail(const Position& pos, const Move& m, int depth); |
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| 50 | |||
| 51 | /** Get a score between 0 and 49, depending of the success/fail ratio of the move. */ |
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| 52 | int getHistScore(const Position& pos, const Move& m) const; |
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| 53 | |||
| 54 | private: |
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| 55 | static int depthWeight(int depth); |
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| 56 | |||
| 57 | static int depthTable[6]; |
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| 58 | |||
| 59 | struct Entry { |
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| 60 | RelaxedShared<int> countSuccess; |
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| 61 | RelaxedShared<int> countFail; |
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| 62 | mutable RelaxedShared<int> score; |
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| 63 | }; |
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| 64 | Entry ht[Piece::nPieceTypes][64]; |
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| 65 | }; |
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| 66 | |||
| 67 | |||
| 68 | inline |
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| 69 | History::History() { |
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| 70 | init(); |
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| 71 | } |
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| 72 | |||
| 73 | inline int |
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| 74 | History::depthWeight(int depth) { |
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| 75 | return depthTable[clamp(depth, 0, (int)COUNT_OF(depthTable)-1)]; |
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| 76 | } |
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| 77 | |||
| 78 | inline void |
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| 79 | History::addSuccess(const Position& pos, const Move& m, int depth) { |
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| 80 | int p = pos.getPiece(m.from()); |
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| 81 | int cnt = depthWeight(depth); |
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| 82 | Entry& e = ht[p][m.to()]; |
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| 83 | int val = e.countSuccess + cnt; |
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| 84 | if (val + e.countFail > 1300) { |
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| 85 | val /= 2; |
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| 86 | e.countFail = e.countFail / 2; |
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| 87 | } |
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| 88 | e.countSuccess = val; |
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| 89 | e.score = -1; |
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| 90 | } |
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| 91 | |||
| 92 | inline void |
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| 93 | History::addFail(const Position& pos, const Move& m, int depth) { |
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| 94 | int p = pos.getPiece(m.from()); |
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| 95 | int cnt = depthWeight(depth); |
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| 96 | Entry& e = ht[p][m.to()]; |
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| 97 | int val = e.countFail + cnt; |
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| 98 | if (val + e.countSuccess > 1300) { |
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| 99 | val /= 2; |
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| 100 | e.countSuccess = e.countSuccess / 2; |
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| 101 | } |
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| 102 | e.countFail = val; |
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| 103 | e.score = -1; |
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| 104 | } |
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| 105 | |||
| 106 | inline int |
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| 107 | History::getHistScore(const Position& pos, const Move& m) const { |
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| 108 | int p = pos.getPiece(m.from()); |
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| 109 | const Entry& e = ht[p][m.to()]; |
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| 110 | int ret = e.score; |
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| 111 | if (ret >= 0) |
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| 112 | return ret; |
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| 113 | int succ = e.countSuccess; |
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| 114 | int fail = e.countFail; |
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| 115 | if (succ + fail > 0) { |
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| 116 | ret = succ * 49 / (succ + fail); |
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| 117 | } else |
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| 118 | ret = 0; |
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| 119 | e.score = ret; |
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| 120 | return ret; |
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| 121 | } |
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| 122 | |||
| 123 | #endif /* HISTORY_HPP_ */ |