Purpose of XUartNs550_SetOptions function?

/****************************************************************************/
/**
*
* Sets the options for the specified driver instance. The options are
* implemented as bit masks such that multiple options may be enabled or
* disabled simultaneously.
*
* The GetOptions function may be called to retrieve the currently enabled
* options. The result is ORed in the desired new settings to be enabled and
* ANDed with the inverse to clear the settings to be disabled. The resulting
* value is then used as the options for the SetOption function call.
*
* @param    InstancePtr is a pointer to the XUartNs550 instance.
* @param    Options contains the options to be set which are bit masks
*        contained in the file xuartns550.h and named XUN_OPTION_*.
*
* @return
*        - XST_SUCCESS if the options were set successfully.
*        - XST_UART_CONFIG_ERROR if the options could not be set because
*        the hardware does not support FIFOs
*
* @note        None.
*
*****************************************************************************/
int XUartNs550_SetOptions(XUartNs550 *InstancePtr, u16 Options)
{
    u32 Index;
    u32 Register;

    /*
     * Assert validates the input arguments
     */
    Xil_AssertNonvoid(InstancePtr != NULL);
    Xil_AssertNonvoid(InstancePtr->IsReady == XIL_COMPONENT_IS_READY);

    /*
     * Loop through the options table to map the logical options to the
     * physical options in the registers of the UART
     */
    for (Index = 0; Index < XUN_NUM_OPTIONS; Index++) {

        /*
         * If the FIFO control register is being read, this is a
         * special case that requires special register processing
         */
        if (OptionsTable[Index].RegisterOffset == XUN_FCR_OFFSET) {
            Register = ReadFcrRegister(InstancePtr->BaseAddress);
        } else {
            /*
             * Read the register which contains option so that the
             * register can be changed without destoying any other
             * bits of the register
             */
            Register = XUartNs550_ReadReg(InstancePtr->BaseAddress,
                    OptionsTable[Index].RegisterOffset);
        }

        /*
         * If the option is set in the input, then set the
         * corresponding bit in the specified register, otherwise
         * clear the bit in the register
         */
        if (Options & OptionsTable[Index].Option) {
            Register |= OptionsTable[Index].Mask;
        } else {
            Register &= ~OptionsTable[Index].Mask;
        }

        /*
         * Write the new value to the register to set the option
         */
        XUartNs550_WriteReg(InstancePtr->BaseAddress,
                 OptionsTable[Index].RegisterOffset, Register);
    }

    /* To be done, add error checks for enabling/resetting FIFOs */

    return XST_SUCCESS;
}

/** @name Configuration options
 * @{
 */
/**
 * These constants specify the options that may be set or retrieved
 * with the driver, each is a unique bit mask such that multiple options
 * may be specified.  These constants indicate the function of the option
 * when in the active state.
 */
#define XUN_OPTION_RXLINE_INTR        0x0800 /**< Enable status interrupt */
#define XUN_OPTION_SET_BREAK        0x0400 /**< Set a break condition */
#define XUN_OPTION_LOOPBACK        0x0200 /**< Enable local loopback */
#define XUN_OPTION_DATA_INTR        0x0100 /**< Enable data interrupts */
#define XUN_OPTION_MODEM_INTR        0x0080 /**< Enable modem interrupts */
#define XUN_OPTION_FIFOS_ENABLE        0x0040 /**< Enable FIFOs */
#define XUN_OPTION_RESET_TX_FIFO    0x0020 /**< Reset the transmit FIFO */
#define XUN_OPTION_RESET_RX_FIFO    0x0010 /**< Reset the receive FIFO */
#define XUN_OPTION_ASSERT_OUT2        0x0008 /**< Assert out2 signal */
#define XUN_OPTION_ASSERT_OUT1        0x0004 /**< Assert out1 signal */
#define XUN_OPTION_ASSERT_RTS        0x0002 /**< Assert RTS signal */
#define XUN_OPTION_ASSERT_DTR        0x0001 /**< Assert DTR signal */
/*@}*/