float_flag_underflow
if ( isTiny && roundBits ) roundData->exception |= float_flag_underflow;
if ( isTiny && roundBits ) roundData->exception |= float_flag_underflow;
if ( isTiny && roundBits ) roundData->exception |= float_flag_underflow;
if ( isTiny && zSig1 ) roundData->exception |= float_flag_underflow;