Help needed: How to make a library from a .ino-file?

Using Arduino Programming Questions
10

Now I ran into a problem which doesn't mean anything to me...

I want to pass the serial port to use for comms to the library in a parameter. In sendData(), I then check this parameter and decide, which Serial to use:

EDIPTFT::EDIPTFT(int port, int smallprotocol) {
  _port = port;
  _smallprotocol = smallprotocol;
}

void EDIPTFT::sendData(char* data, int len) {
  if (_smallprotocol > 0) {
  }
  else {
    unsigned char i;
    for(i=0; i < len; i++) {
      switch (_port) {
	case 0 : {
	  Serial.write(data[i]);
	  break;
	}
	case 1 : {
	  Serial1.write(data[i]);
	  break;
	}
	case 2 : {
	  Serial2.write(data[i]);
	  break;
	}
	case 3 : {
	  Serial3.write(data[i]);
	  break;
	}
      }
    }
  }
}

I use this library from a sketch that also uses the FastSerial library. Now, when I try to compile everything, I get this errors:

core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `__vector_25'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
/opt/arduino-1.0.3/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../avr/bin/ld: Disabling relaxation: it will not work with multiple definitions
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `__vector_36'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `__vector_51'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `__vector_54'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `Serial'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
/opt/arduino-1.0.3/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../avr/bin/ld: Warning: size of symbol `Serial' changed from 29 in UxV_CS.cpp.o to 34 in core.a(HardwareSerial.cpp.o)
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `Serial1'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
/opt/arduino-1.0.3/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../avr/bin/ld: Warning: size of symbol `Serial1' changed from 29 in UxV_CS.cpp.o to 34 in core.a(HardwareSerial.cpp.o)
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `Serial2'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
/opt/arduino-1.0.3/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../avr/bin/ld: Warning: size of symbol `Serial2' changed from 29 in UxV_CS.cpp.o to 34 in core.a(HardwareSerial.cpp.o)
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `Serial3'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
/opt/arduino-1.0.3/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../avr/bin/ld: Warning: size of symbol `Serial3' changed from 29 in UxV_CS.cpp.o to 34 in core.a(HardwareSerial.cpp.o)
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `__vector_26'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `__vector_37'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `__vector_52'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here
core.a(HardwareSerial.cpp.o): In function `global constructors keyed to rx_buffer':
/opt/arduino-1.0.3/hardware/arduino/cores/arduino/HardwareSerial.cpp:515: multiple definition of `__vector_55'
UxV_CS.cpp.o:/opt/arduino-1.0.3/UxV_CS.ino:79: first defined here

This is way out of my league... What do I do now?