private string FormatDecimal (int precision, NumberFormatInfo nfi)
{
if (precision < _digitsLen)
precision = _digitsLen;
if (precision == 0)
return "0";
ResetCharBuf (precision + 1);
if (!_positive)
Append (nfi.NegativeSign);
AppendDigits (0, precision);
return new string (_cbuf, 0, _ind);
}