private static TypeData toPrimitiveTag(char c) {
        switch (c) {
        case 'Z' :
        case 'C' :
        case 'B' :
        case 'S' :
        case 'I' :
            return TypeTag.INTEGER;
        case 'J' :
            return TypeTag.LONG;
        case 'F' :
            return TypeTag.FLOAT;
        case 'D' :
            return TypeTag.DOUBLE;
        case 'V' :
        default :
            return null;
        }
    }