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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 | * killerTable.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 KILLERTABLE_HPP_ |
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| 27 | #define KILLERTABLE_HPP_ |
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| 28 | |||
| 29 | #include "util/util.hpp" |
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| 30 | #include "move.hpp" |
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| 31 | #include <cassert> |
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| 32 | |||
| 33 | |||
| 34 | /** |
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| 35 | * Implement a table of killer moves for the killer heuristic. |
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| 36 | */ |
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| 37 | class KillerTable { |
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| 38 | public: |
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| 39 | /** Create an empty killer table. */ |
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| 40 | KillerTable(); |
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| 41 | |||
| 42 | /** Clear killer table. */ |
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| 43 | void clear(); |
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| 44 | |||
| 45 | /** Add a killer move to the table. Moves are replaced on an LRU basis. */ |
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| 46 | void addKiller(int ply, const Move& m); |
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| 47 | |||
| 48 | /** |
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| 49 | * Get a score for move m based on hits in the killer table. |
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| 50 | * The score is 4 for primary hit at ply. |
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| 51 | * The score is 3 for secondary hit at ply. |
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| 52 | * The score is 2 for primary hit at ply - 2. |
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| 53 | * The score is 1 for secondary hit at ply - 2. |
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| 54 | * The score is 0 otherwise. |
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| 55 | */ |
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| 56 | int getKillerScore(int ply, const Move& m) const; |
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| 57 | |||
| 58 | private: |
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| 59 | /** There is one KTEntry for each ply in the search tree. */ |
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| 60 | struct KTEntry { |
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| 61 | KTEntry(); |
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| 62 | RelaxedShared<int> move0; |
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| 63 | RelaxedShared<int> move1; |
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| 64 | }; |
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| 65 | KTEntry ktList[200]; |
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| 66 | }; |
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| 67 | |||
| 68 | inline |
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| 69 | KillerTable::KillerTable() { |
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| 70 | } |
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| 71 | |||
| 72 | inline |
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| 73 | KillerTable::KTEntry::KTEntry() |
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| 74 | : move0(0), move1(0) { |
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| 75 | } |
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| 76 | |||
| 77 | inline void |
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| 78 | KillerTable::addKiller(int ply, const Move& m) { |
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| 79 | if (ply >= (int)COUNT_OF(ktList)) |
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| 80 | return; |
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| 81 | int move = (short)(m.from() + (m.to() << 6) + (m.promoteTo() << 12)); |
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| 82 | KTEntry& ent = ktList[ply]; |
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| 83 | if (move != ent.move0) { |
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| 84 | ent.move1 = ent.move0; |
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| 85 | ent.move0 = move; |
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| 86 | } |
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| 87 | } |
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| 88 | |||
| 89 | inline int |
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| 90 | KillerTable::getKillerScore(int ply, const Move& m) const { |
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| 91 | int move = (short)(m.from() + (m.to() << 6) + (m.promoteTo() << 12)); |
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| 92 | if (ply < (int)COUNT_OF(ktList)) { |
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| 93 | const KTEntry& ent = ktList[ply]; |
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| 94 | if (move == ent.move0) { |
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| 95 | return 4; |
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| 96 | } else if (move == ent.move1) { |
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| 97 | return 3; |
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| 98 | } |
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| 99 | } |
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| 100 | if ((ply - 2 >= 0) && (ply - 2 < (int)COUNT_OF(ktList))) { |
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| 101 | const KTEntry& ent = ktList[ply - 2]; |
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| 102 | if (move == ent.move0) { |
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| 103 | return 2; |
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| 104 | } else if (move == ent.move1) { |
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| 105 | return 1; |
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| 106 | } |
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| 107 | } |
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| 108 | return 0; |
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| 109 | } |
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| 110 | |||
| 111 | #endif /* KILLERTABLE_HPP_ */ |