bits.swift

import UIKit

public enum Bit: Int {
    case zero
    case one
}

extension Bit {
    func inverted() -> Bit {
        return self == .zero ? .one : .zero
    }
}

/** build bit pattern from array of bits */
@_specialize(exported: true, where T == UInt8)
func integerFrom<T: FixedWidthInteger>(_ bits: Array<Bit>) -> T {
    var bitPattern: T = 0
    for idx in bits.indices {
        if bits[idx] == Bit.one {
            let bit = T(UInt64(1) << UInt64(idx))
            bitPattern = bitPattern | bit
        }
    }
    return bitPattern
}

extension UInt8 {
    init(bits: [Bit]) {
        self.init(integerFrom(bits) as UInt8)
    }
}

let expectedOutput: UInt8 = 0x47
let input: [Bit] = [
    .zero,
    .one,
    .zero,
    .zero,
    .zero,
    .one,
    .one,
    .one
]

let output = UInt8(bits: input)

print(expectedOutput)   // 71
print(output)           // 226