Ionic.Zlib.GZipStream.EmitHeader C# (CSharp) Method

        private int EmitHeader()
        {
            byte[] commentBytes = (Comment == null) ? null : iso8859dash1.GetBytes(Comment);
            byte[] filenameBytes = (FileName == null) ? null : iso8859dash1.GetBytes(FileName);

            int cbLength = (Comment == null) ? 0 : commentBytes.Length + 1;
            int fnLength = (FileName == null) ? 0 : filenameBytes.Length + 1;

            int bufferLength = 10 + cbLength + fnLength;
            byte[] header = new byte[bufferLength];
            int i = 0;
            // ID
            header[i++] = 0x1F;
            header[i++] = 0x8B;

            // compression method
            header[i++] = 8;
            byte flag = 0;
            if (Comment != null)
                flag ^= 0x10;
            if (FileName != null)
                flag ^= 0x8;

            // flag
            header[i++] = flag;

            // mtime
            if (!LastModified.HasValue) LastModified = DateTime.Now;
            System.TimeSpan delta = LastModified.Value - _unixEpoch;
            Int32 timet = (Int32)delta.TotalSeconds;
            Array.Copy(BitConverter.GetBytes(timet), 0, header, i, 4);
            i += 4;

            // xflg
            header[i++] = 0;    // this field is totally useless
            // OS
            header[i++] = 0xFF; // 0xFF == unspecified

            // extra field length - only if FEXTRA is set, which it is not.
            //header[i++]= 0;
            //header[i++]= 0;

            // filename
            if (fnLength != 0)
            {
                Array.Copy(filenameBytes, 0, header, i, fnLength - 1);
                i += fnLength - 1;
                header[i++] = 0; // terminate
            }

            // comment
            if (cbLength != 0)
            {
                Array.Copy(commentBytes, 0, header, i, cbLength - 1);
                i += cbLength - 1;
                header[i++] = 0; // terminate
            }

            _baseStream._stream.Write(header, 0, header.Length);

            return header.Length; // bytes written
        }