XML Transponder

using System;
using System.IO;

namespace iOSTest
{
    public class TextTransponder : MemoryStream
    {
        private static readonly bool[] _charTable = new bool[256];
        static TextTransponder()
        {
            int len = _charTable.Length;
            while (len > 0) _charTable [--len] = true;

            len = 0;
            while (len < 8) _charTable [len++] = false;

            len = 14;
            while (len < 32) _charTable [len++] = false;

            _charTable [11] = _charTable [12] = false;
        }

        public TextTransponder (FileStream src) : base(src.Length)
        {
            long oldPos = src.Position;
            src.Position = 0;

            int len = src.Length;
            while (len-- > 0) {
                byte c = src.ReadByte ();
                if (_charTable [c])
                    this.WriteByte (c);
            }

            src.Position = oldPos;
            this.Position = 0;
        }

    }
}