Swiftでつくるファミコンエミュレータのススメ

iOSDC 2019 ルーキーズLT発表資料
https://fortee.jp/iosdc-japan-2019/proposal/92904657-beda-46fe-8ecb-b27c75ee0f16

Transcript

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

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4. ໨ඪ
   

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5. $16 116
   13(30.
   $)"30.
   3".
   

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9. ϑΝϛίϯΤϛϡϨʔλΛ
   SwiftͰॻ͘͜ͱͷϝϦοτ
   

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10. ϝϦοτ 1
    ݻఆ௕੔਺ܕ
    

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11. ݻఆ௕੔਺ܕ
    • UInt8 / Int8
    • UInt16 / Int16
    • UInt32 / Int32
    • ͜ΕΒ͕ͳ͚Ε͹ɺANDԋࢉͩΒ͚ʹͳΔ
    • Javaܥͱ͔LLͱ͔͸͜Ε͕͠ΜͲ͍͔΋
    

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

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

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14. ϝϦοτ 2
    Overflow Operator
    

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15. Overflow Operator
    // 65535
    let value = UInt16.max
    // 0
    let result = value &+ 1
    

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16. ϝϦοτ 3
    OptionSet
    

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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)
    }
    

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18. ҙਤ͕Θ͔Γ΍͍͢Ϗοτԋࢉ
    // 0b1001100
    var cpuStatus: Status = [.V, .D, .I]
    // 0b1001100 & ~0b00001101 = 0b1000000
    cpuStatus.remove([.C, .D, .I])
    // 0b1000000 | 0b0000001 = 0b1000001
    cpuStatus.formUnion(.C)
    

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19. ϝϦοτ 4
    ύϑΥʔϚϯε
    

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20. swift run -c debug
    3 FPS
    

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21. swift run -c release
    100 FPS
    

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

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

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24. ϋϚͬͨ͜ͱ
    

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25. Release BuildͷΈ
    ϨϯμϦϯά͞Εͳ͍
    

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26. PureSwift/SDL
    public func copy(_ texture: SDLTexture,
    source: SDL_Rect? = nil,
    destination: SDL_Rect? = nil) throws
    {
    let srcPtr: UnsafePointer?
    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
    

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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))
    }
    

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

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29. ΤϛϡϨʔλ։ൃλΠϜϥΠϯ
    

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