deserialization.swift

enum Endianness {
    case Big
    case Little
    
    func swapWithNative(slice: Slice<UInt8>) -> Slice<UInt8> {
        #if true
        let native = Little
        #else
        let native = Big
        #endif
        
        return (self == native ? slice : slice.reverse())
    }
}

func DeserializeBytes<T>(storage: [UInt8], offset: Int, _ endianness: Endianness = .Big) -> T {
    let swap = true
    
    let size = sizeof(T)
    let slice = storage[offset..<(offset + size)]
    let swapped = endianness.swapWithNative(slice)
    
    return swapped.withUnsafePointerToElements{ UnsafePointer<T>($0).memory }
}

struct Y {
    let storage: [UInt8]
    var field: Int8 { return DeserializeBytes(storage, 0) }
    var field2: Int32 { return DeserializeBytes(storage, 1) }
}

let y = Y(storage: [ 1, 0, 1, 0, 0 ])
println(y.field, y.field2)