static protected void FillBuff() throws java.io.IOException
  {
    if (maxNextCharInd == available)
    {
      if (available == bufsize)
      {
        if (tokenBegin > 2048)
        {
          bufpos = maxNextCharInd = 0;
          available = tokenBegin;
        }
        else if (tokenBegin < 0)
          bufpos = maxNextCharInd = 0;
        else
          ExpandBuff(false);
      }
      else if (available > tokenBegin)
        available = bufsize;
      else if ((tokenBegin - available) < 2048)
        ExpandBuff(true);
      else
        available = tokenBegin;
    }

    int i;
    try {
      if ((i = inputStream.read(buffer, maxNextCharInd, available - maxNextCharInd)) == -1)
      {
        inputStream.close();
        throw new java.io.IOException();
      }
      else
        maxNextCharInd += i;
      return;
    }
    catch(java.io.IOException e) {
      --bufpos;
      backup(0);
      if (tokenBegin == -1)
        tokenBegin = bufpos;
      throw e;
    }
  }