we need to be sure that the mantissa is normalized. we might have a mantissa of 0x0AAB0000 with exponent 0 vs 0x000AAA with exponent 4. We need to do something like

`
if (exponent < a.exponent) {
   mantissa  <<= (a.exponent  - exponent)
   exponent = a.exponent
}
`
or something like that. Then once exponents are the same, we can just compare the mantissa