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Francois
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,94 @@ | ||
| /* | ||
| * This file is part of my swift adapation of Connect4 Game Solver | ||
| * <http://connect4.gamesolver.org> by Pascal Pons <[email protected]> | ||
| * Copyright (C) 2021 Francois Heuchamps | ||
| * | ||
| * Connect4 Game Solver is free software: you can redistribute it and/or | ||
| * modify it under the terms of the GNU Affero General Public License as | ||
| * published by the Free Software Foundation, either version 3 of the | ||
| * License, or (at your option) any later version. | ||
| * | ||
| * Connect4 Game Solver is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU Affero General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU Affero General Public License | ||
| * along with Connect4 Game Solver. If not, see <http://www.gnu.org/licenses/>. | ||
| */ | ||
|
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| import Foundation | ||
|
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| /** | ||
| * Transposition Table is a simple hash map with fixed storage size. | ||
| * In case of collision we keep the last entry and overide the previous one. | ||
| * | ||
| * We use 56-bit keys and 8-bit non-null values | ||
| */ | ||
| final internal class TranspositionTable { | ||
|
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| private var table : UnsafeMutablePointer<UInt> | ||
| private var size : Int | ||
|
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| /** | ||
| * Allocate and initialize to zero a mutable pointer. | ||
| * We don't use UnsafeMutableBufferPointer because we don't need collection protocol | ||
| * We'll store a 56 bit key in low bytes and an 8 bit value in high byte | ||
| * - parameter size: number of entries | ||
| */ | ||
| internal init(size: Int) { | ||
| self.size = size | ||
| table = UnsafeMutablePointer<UInt>.allocate(capacity: size) | ||
| table.initialize(repeating: .zero, count: size) | ||
| } | ||
|
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| deinit { | ||
| table.deallocate() | ||
| } | ||
|
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| /** | ||
| * Compute the index in the transition table for the given key. | ||
| */ | ||
| private func index(for key: UInt) -> Int { | ||
| Int(bitPattern: key) % size | ||
| } | ||
|
|
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| /** | ||
| * Store a value for a given key | ||
| * - parameter key: 56-bit key | ||
| * - parameter value: non-null 8-bit value. null (0) value are used to encode missing data. | ||
| */ | ||
| internal func put(key: UInt, value: Int) { | ||
| assert(key < (UInt(1) << 56)) | ||
| assert(value < (1 << 8)) | ||
| assert(value > -(1 << 8)) | ||
|
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| let position = index(for: key) | ||
| let entryPointer = table.advanced(by: position) | ||
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| entryPointer.pointee = (key + (UInt(bitPattern: value) << 56)) | ||
| } | ||
|
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| /** | ||
| * Get the value of a key | ||
| * - parameter key: 56-bit key | ||
| * - parameter value: 8-bit value associated with the key if present, 0 otherwise. | ||
| */ | ||
| internal func get(key: UInt) -> Int { | ||
| assert(key < (UInt(1) << 56)) | ||
|
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| let position = index(for: key) | ||
| let entry = table.advanced(by: position).pointee | ||
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| guard entry & ((1 << 56) - 1) == key else { return 0 } | ||
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| return Int(bitPattern: (entry >> 56)) | ||
| } | ||
|
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| /** | ||
| * Empty the Transition Table. | ||
| */ | ||
| internal func reset() { | ||
| table.assign(repeating: .zero, count: size) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,39 @@ | ||
| // | ||
| // TranspositionTableTests.swift | ||
| // Connect4Tests | ||
| // | ||
| // Created by Francois on 09/02/2021. | ||
| // | ||
|
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| import XCTest | ||
| @testable import Connect4 | ||
|
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| class TranspositionTableTests: XCTestCase { | ||
|
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| func testInit() throws { | ||
| let table = TranspositionTable(size: 97) | ||
| XCTAssertEqual(table.get(key: 42), 0) | ||
| } | ||
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| func testPutAndGet() throws { | ||
| let table = TranspositionTable(size: 97) | ||
|
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| table.put(key:42, value: 1) | ||
| table.put(key:96, value: 2) | ||
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| XCTAssertEqual(table.get(key: 42), 1) | ||
| XCTAssertEqual(table.get(key: 96), 2) | ||
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| table.put(key: 42 + 97, value: 3) | ||
| XCTAssertEqual(table.get(key: 42), 0) | ||
| XCTAssertEqual(table.get(key: 42 + 97), 3) | ||
| } | ||
|
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| func testReset() throws { | ||
| let table = TranspositionTable(size: 97) | ||
| table.put(key:42, value: 1) | ||
| table.reset() | ||
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| XCTAssertEqual(table.get(key: 42), 0) | ||
| } | ||
| } |