/* The function is used to Set Bus Clock.  */
void SysCtlBusClkSet(unsigned long ulBusClk)
/* The function is used to Set Bus Clock.  */
void SysCtlBusClkSet(unsigned long ulBusClk)
{
    unsigned long ulHclk = 0, ulSysDiv;
    xASSERT((ulBusClk > 0 && ulBusClk <= 24000000));
    ulHclk = SysCtlHClockGet();
    if (ulBusClk <= ulHclk)
    {
        xASSERT(ulBusClk <= ulHclk);
        for(ulSysDiv = 1; ulSysDiv < 8; ulSysDiv++)
        {
            if((ulHclk / (ulSysDiv + 1)) <= ulBusClk)
            {
                break;
            }
        }
        xHWREG(SIM_CLKDIV1) &= ~SIM_CLKDIV1_OUTDIV4_M;
        xHWREG(SIM_CLKDIV1) |= (ulSysDiv << SIM_CLKDIV1_OUTDIV4_S);
    }
}