Encoding bin files generator

Generator.cs

// Encoding bin files generator for Encoding for Silverlight project
// https://encoding4silverlight.codeplex.com/

using System.IO;
using System.Linq;
using System.Text;

class Program
{
    private const char LEAD_BYTE_CHAR = '\uFFFE';
    private const char UNICODE_REPLACEMENT_CHAR = '\uFFFD';

    static void Main(string[] args)
    {
        var dbcs = Encoding.GetEncoding(936).GetType(); // Chinese Simplified (GB2312)
        var encodings = Encoding.GetEncodings().Where(s => s.GetEncoding().GetType() == dbcs).ToArray();

        foreach (var ei in encodings)
        {
            Encoding e = ei.GetEncoding();

            bool[] flags = new bool[0x10000];

            using (FileStream fs = new FileStream(ei.Name + ".bin", FileMode.Create))
            using (BinaryWriter writer = new BinaryWriter(fs))
            {
                for (int i = 0; i < 0xffff; i++)
                {
                    string s1 = ((char)i).ToString();
                    byte[] buf = e.GetBytes(s1);
                    ushort u = 0;
                    if (buf.Length == 1)
                    {
                        u = buf[0];
                    }
                    else
                    {
                        u = (ushort)(buf[0] << 8 | buf[1]);
                        flags[buf[0]] = true;
                    }
                    if (i == UNICODE_REPLACEMENT_CHAR)
                        u = 0;
                    writer.Write(u);
                }

                for (int i = 0; i < 0xffff; i++)
                {
                    byte[] buf = new byte[2];
                    if (i < 0x100)
                    {
                        buf[0] = (byte)(i & 0xff);
                    }
                    else
                    {
                        buf[0] = (byte)((i >> 8) & 0xff);
                        buf[1] = (byte)(i & 0xff);
                    }
                    ushort u = (ushort)e.GetChars(buf)[0];
                    if (flags[i])
                        u = LEAD_BYTE_CHAR;
                    writer.Write(u);
                }
                fs.Flush();
            }
        }
    }
}