Swiftでつくるファミコンエミュレータのススメ

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1. SwiftͰͭ͘Δ ϑΝϛίϯΤϛϡϨʔλͷ εεϝ 2019-09-05 iOSDC Japan 2019 thara @zetta1985

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4. ໨ඪ

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9. ϑΝϛίϯΤϛϡϨʔλΛ SwiftͰॻ͘͜ͱͷϝϦοτ

10. ϝϦοτ 1 ݻఆ௕੔਺ܕ

11. ݻఆ௕੔਺ܕ • UInt8 / Int8 • UInt16 / Int16 •

    UInt32 / Int32 • ͜ΕΒ͕ͳ͚Ε͹ɺANDԋࢉͩΒ͚ʹͳΔ • Javaܥͱ͔LLͱ͔͸͜Ε͕͠ΜͲ͍͔΋

12. ࢀߟɿJava࣮૷ͷ৔߹ https://github.com/andrew-hoffman/halfnes

13. ࢀߟɿTypeScript࣮૷ͷ৔߹ https://github.com/r7kamura/nes8

14. ϝϦοτ 2 Overflow Operator

15. Overflow Operator // 65535 let value = UInt16.max // 0

    let result = value &+ 1

16. ϝϦοτ 3 OptionSet

17. ϏοτϚεΫఆٛ struct Status: OptionSet { let rawValue: UInt8 /// Negative

    static let N = Status(rawValue: 1 << 7) /// Overflow static let V = Status(rawValue: 1 << 6) /// Decimal mode static let D = Status(rawValue: 1 << 3) /// IRQ prevention static let I = Status(rawValue: 1 << 2) /// Zero static let Z = Status(rawValue: 1 << 1) /// Carry static let C = Status(rawValue: 1 << 0) /// The B flag static let B = Status(rawValue: 0b00110000) }

18. ҙਤ͕Θ͔Γ΍͍͢Ϗοτԋࢉ // 0b1001100 var cpuStatus: Status = [.V, .D, .I]

    // 0b1001100 & ~0b00001101 = 0b1000000 cpuStatus.remove([.C, .D, .I]) // 0b1000000 | 0b0000001 = 0b1000001 cpuStatus.formUnion(.C)

19. ϝϦοτ 4 ύϑΥʔϚϯε

20. swift run -c debug 3 FPS

21. swift run -c release 100 FPS

22. ؾΛ͚͍ͭͯͨ͜ͱ • ΦϒδΣΫτΛແବʹ࡞Βͳ͍ • ΫϩʔδϟΛಈతʹ࡞Βͳ͍ • ແବͳܭࢉ͸͠ͳ͍ • ܧঝ͠ͳ͍Ϋϥεʹ͸finalΛ͚ͭΔ •

    ͳΔ΂͘privateʹ͢Δ

23. ͜ͷఔ౓ͷҙࣝͰ΋ 100FPSग़Δ ↓ Θ͔Γ΍͢͞ΛॏࢹͰ͖Δ

24. ϋϚͬͨ͜ͱ

25. Release BuildͷΈ ϨϯμϦϯά͞Εͳ͍

26. PureSwift/SDL public func copy(_ texture: SDLTexture, source: SDL_Rect? = nil,

    destination: SDL_Rect? = nil) throws { let srcPtr: UnsafePointer<SDL_Rect>? if let rect = source { srcPtr = withUnsafePointer(to: rect) { $0 } } else { srcPtr = nil } ... try SDL_RenderCopy(ptr, texture.ptr, sourcePointer, destPtr).sdlThrow(... } https://github.com/PureSwift/SDL

27. thara/SDL public func copy(_ texture: SDLTexture, _ s: inout SDL_Rect,

    _ d: inout SDL_Rect) throws { try SDL_RenderCopy(ptr, texture.ptr, &s, &d).sdlThrow(type: type(of: self)) } public func copy(_ texture: SDLTexture, _ s: inout SDL_Rect) throws { try SDL_RenderCopy(ptr, texture.ptr, &s, nil).sdlThrow(type: type(of: self)) } public func copy(_ texture: SDLTexture, _ d: inout SDL_Rect) throws { try SDL_RenderCopy(ptr, texture.ptr, nil, &d).sdlThrow(type: type(of: self)) }

28. ·ͱΊ • SwiftͰ͸ίʔυͷΘ͔Γ΍͢͞Λॏࢹͯ͠ΤϛϡϨʔλ։ൃͰ͖Δ • ݻఆ௕੔਺ܕͰϊΠζͱͳΔϚεΫ͕ෆཁ • Overflow OperatorͰϥοϓΞϥ΢ϯυ͢Δԋࢉ͕ࣗ໌ • OptionSetʹΑΔϏοτϚεΫͷߴ͍දݱྗ

    • ίϯύΠϥͷ࠷దԽ͕͍͢͝ • ͗ͯ͢͢͝όάͷݪҼ͕Θ͔Βͳ͍

29. ΤϛϡϨʔλ։ൃλΠϜϥΠϯ

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