Mods to HardwareSerial to handle 9-bit data

HI nick....

i am using arduino mega on 1.8.3 arduino ide.
whien i am using hardwareSerial lib to read MDB DATA than my compiler make error.
please tell me step if i am doing wrong.
the compiler make the error on this line

"void HardwareSerial::begin(unsigned long baud, byte config, bool use9Bits)"

and the error msg is like:

"HardwareSerial.cpp:109: error: prototype for 'void HardwareSerial::begin(long unsigned int, byte, bool)' does not match any in class 'HardwareSerial'

void HardwareSerial::begin(unsigned long baud, byte config, bool use9Bits)

^

In file included from C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/Arduino.h:232:0,

from sketch\HardwareSerial.cpp:30:

HardwareSerial.h:122: error: candidates are: void HardwareSerial::begin(long unsigned int, uint8_t)

void begin(unsigned long, uint8_t);

^

HardwareSerial.h:121: error: void HardwareSerial::begin(long unsigned int)

void begin(unsigned long baud) { begin(baud, SERIAL_8N1); }

^

HardwareSerial.cpp:228: error: no 'size_t HardwareSerial::write9bit(uint16_t)' member function declared in class 'HardwareSerial'

size_t HardwareSerial::write9bit(uint16_t c)

^

exit status 1
prototype for 'void HardwareSerial::begin(long unsigned int, byte, bool)' does not match any in class 'HardwareSerial'

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.""

thanks in advance!!!! and sorry for my English if you feel problem for understanding......