bf53x_touch那个范例里面，int read_x(void)或int read_y(void)这两个函式在送出命令后都会再多送出8个clock后才开始抓取12bit转换数据，如下所示，但是规格书上并没有要求，请问原因为何？

int read_x(void)

{

        int x_dat =0;

        int temp = 0;

        delay(0xff);

        *pSPI_FLG&= ~FLG2;      

        delay(0xff);

        spi_byte_rw(0x90);

        delay(0xff);

        spi_byte_rw(0x00);  //多送出8个clok

        x_dat =(spi_byte_rw(0x00)&0xff)<<1;

        temp =(spi_byte_rw(0x00)&0xff)<<1;

        x_dat =(x_dat<<8)|temp;

        x_dat>>=4;    

        *pSPI_FLG |=FLG2;                    

        delay(0xff);

        return x_dat;

}