libs.nfc/NFC/Helper/HexConverter.cs

using System;

namespace NFC.Helper
{
    /// <summary>
    /// Converts to and from Byte Array from and to String
    /// </summary>
    public static class HexConverter
    {
        /// <summary>
        /// Converts byte[] to string with HEX Code
        /// No 0x is created
        /// </summary>
        /// <param name="data">Data</param>
        public static string ConvertToHexString(byte[] data)
        {
            return BitConverter.ToString(data).Replace("-", "").ToLower();
        }

        /// <summary>
        /// Converts string with HEX Code to byte[]
        /// No 0x is requiered
        /// </summary>
        /// <param name="data">Data</param>
        public static byte[] ConvertFromHexString(string data)
        {
            if (data.Length % 2 == 1)
                throw new Exception("Data Length is uneven.");

            byte[] arr = new byte[data.Length >> 1];

            for (int i = 0; i < data.Length >> 1; ++i)
            {
                arr[i] = (byte)((GetHexVal(data[i << 1]) << 4) + (GetHexVal(data[(i << 1) + 1])));
            }

            return arr;
        }

        private static int GetHexVal(char hex)
        {
            int val = (int)hex;
            //For uppercase A-F letters:
            //return val - (val < 58 ? 48 : 55);
            //For lowercase a-f letters:
            //return val - (val < 58 ? 48 : 87);
            //Or the two combined, but a bit slower:
            return val - (val < 58 ? 48 : (val < 97 ? 55 : 87));
        }
    }
}