MSP430 SPI 12 bit to 8 bit ?

#define RFM_REN      P3REN
#define RFM_DIR      P3DIR
#define RFM_IN       P3IN
#define RFM_OUT      P3OUT

#define RFM_CS_PIN   (1<<7)
#define RFM_SCL_PIN  (1<<3)
#define RFM_MISO_PIN (1<<2)
#define RFM_MOSI_PIN (1<<1)
#define RFM_NIRQ_PIN (1<<6)


unsigned int spi_shift16(unsigned int data)
{
    unsigned int result = 0;
    unsigned char width;
    RFM_OUT &= ~(RFM_SCL_PIN);             //init clock low
    RFM_OUT &= ~(RFM_CS_PIN);             //begin transmit - cs low
    for (width=0; width<16; width++)
    {
        if (data & 0x8000)
        {   //check bit and set data line accordingly
            RFM_OUT |= RFM_MOSI_PIN;
        }
        else
        {
            RFM_OUT &= ~(RFM_MOSI_PIN);
        }
        RFM_OUT |= RFM_SCL_PIN;          //end bit - clock high
        result <<= 1;
        if((RFM_IN & RFM_MISO_PIN) == RFM_MISO_PIN)
        	result |= 0x00001;
		RFM_OUT &= ~(RFM_SCL_PIN);        //begin bit - clock low
        data <<= 1;
    }
    RFM_OUT |= RFM_CS_PIN;               //end transmit
    return result;
}