Datas.swift

//
//  Datas.swift
//  PotentCodables
//
//  Copyright © 2021 Outfox, inc.
//
//
//  Distributed under the MIT License, See LICENSE for details.
//

import Foundation

extension Data {

  func hexEncodedString() -> String {
    return reduce("") {$0 + String(format: "%02x", $1)}
  }

  init(hexEncoded: String) {

    let chars = Array(hexEncoded.utf8)

    var bytes = [UInt8]()
    bytes.reserveCapacity(chars.count / 2)

    let map: [UInt8] = [
      0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, // 01234567
      0x08, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 89:;<=>?
      0x00, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x00, // @ABCDEFG
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // HIJKLMNO
    ]

    for i in stride(from: 0, to: chars.count, by: 2) {
      let index1 = Int(chars[i] & 0x1F ^ 0x10)
      let index2 = Int(chars[i + 1] & 0x1F ^ 0x10)
      bytes.append(map[index1] << 4 | map[index2])
    }

    self.init(bytes)
  }

}