Don't do it like that, print it like this using 16-character padding for the hex numbers (they are 64-bit):
::printf("Point X: %16X%16X%16X%16X \n", P.x.bits64[3], P.x.bits64[2], P.x.bits64[1], P.x.bits64[0]);
::printf("Point Y: %16X%16X%16X%16X \n", P.y.bits64[3], P.y.bits64[2], P.y.bits64[1], P.y.bits64[0]);