setting GPIO port of MSP430 G2553 for 3x4 Keypad interfacing on MSP-EXP430G2 Launchpad.

I have been trying to interface a 3x4 keypad on the MSP-EXP430G2 Launchpad.

Somehow while scanning the keys for button press i have been facing the problem that P1IN bits are reversed.

I was wondering if i missed something while setting the port.

here is what i have done.

/*
* I am using 3x4 keypad. Lower nibbles  Pins 0 to 3 are Rows. Upper nibbles 4 to 6 are Columns. 7th nibble is not connected.
* Columns are INPUT (P1.4, P1.5, P1.6) and Rows are Outputs(P1.0, P1.1, P1.2, P1.3)
*/

	P1SEL=0x00;
	P1SEL2=0x00;
	P1DIR=0x0F;									//P1.0, P1.1, P1.2, P1.3 used as Outputs(Rows) and P1.4, P1.5, P1.6 used as Inputs(Columns).
												//While P1.7 is not used.i.e because we are using 3x4 keypad

	P1IE=P1IE|(BIT4+BIT5+BIT6);					//Interrupts on Columns (INPUTS) P1.4, 1.5, P1.6
	P1IES=P1IES|(BIT4+BIT5+BIT6);				// Interrupt Edge Select from Hi->Lo
	P1REN=P1REN|(BIT4+BIT5+BIT6+BIt7);			// Pull up Resistor on Columns (INPUT) P1.4, P1.5, P1.6 (also P1.7 to be safe.)
	P1OUT=0xF0;// I am not sure of this

}

//for scanning the keys once inside the ISR i have have written this

    char masked;
    P1OUT=0xFE;
    masked=P1OUT&0xF0;                            // This will mask of lower bits P1.0 to P1.3.


    switch(masked)
    {
    case 0xE0:    return('1');                    // if E0 then it will return 1
    case 0xD0:    return('2');                    // if D0 then it will return 2
    case 0xB0:    return('3');                    // if B0 then it will return 3
    default:    error=('X');                    // if anything else then it will return an error.
    }

/* Not sure if its a good idea to use P1IF register to scan for the button as i suspect it would change while in ISR*/

Would be grateful if anyone can spare some time and can point out the mistake here.