meaning of "0xFFFF != *((Uint16*)GetAdcOffsetTrimOTP)"?

Other Parts Discussed in Thread: TMS320F28335, TMS320F28377S

Example Project "adc_soc_epwm_cpu01"

void AdcSetMode(Uint16 adc, Uint16 resolution, Uint16 signalmode)
{
Uint16 adcOffsetTrimOTPIndex; //index into OTP table of ADC offset trims
Uint16 adcOffsetTrim; //temporary ADC offset trim

CalAdcINL(adc);

if(0xFFFF != *((Uint16*)GetAdcOffsetTrimOTP)) <- meaning of "0xFFFF" ??
{
adcOffsetTrimOTPIndex = 4*adc + 2*resolution + 1*signalmode;
adcOffsetTrim = (*GetAdcOffsetTrimOTP)(adcOffsetTrimOTPIndex);
}
else
{
adcOffsetTrim = 0;
}

and similar codes in CalAdcINL( )

void CalAdcINL(Uint16 adc)
{
switch(adc)
{
case ADC_ADCA:
if(0xFFFF != *((Uint16*)CalAdcaINL)) <- meaning of 0xFFFF?
{
(*CalAdcaINL)(); <- why do (*CalAdcalINL)() recall?
}
else
{
}
break;
~codes~
}
}