[Doc bug] Units of NtpResult.seconds_fraction ambiguous

[svet-b]

Thanks for a really helpful library! Though I ran into an issue trying to parse NtpResult.seconds_fraction (resp. NtpResult.sec_fraction()):

1. This states that the value is in microseconds: https://github.com/vpetrigo/sntpc/blob/master/src/lib.rs#L280
2. This states nanoseconds: https://github.com/vpetrigo/sntpc/blob/master/src/lib.rs#L292
3. In the example it's in units of 1/u32::MAX of a second (if my reading is right) - i.e. about a quarter of a nanosecond: https://github.com/vpetrigo/sntpc/blob/master/examples/simple_request.rs#L87

I gather that (1) is definitely not the case (since the values are too large), and I suspect that (3) is the real answer, but it would be good to have this clear in the docs. Or perhaps convert the result to micro or nanoseconds, since 1/u32::MAX is a bit awkward to deal with.

Also - and this is minor - but I think in the example using time.sec_fraction() as u64 * 1_000_000 / u32::MAX as u64 to get the decimal points will show the wrong value if the result has fewer than 6 digits. E.g. it would show 1.23 instead of 1.000023. Might be better to just convert to float, e.g.

println!("Got time: {}", time.sec() as f64 + time.sec_fraction() as f64 / u32::MAX as f64);

[vpetrigo]

Hello @svet-b,
Sorry for the late reply!

Thank you for pointing out. Since we have a second fractional value in the low 32 bit we can convert it to the fractional part representation by dividing it by 2^32 - single bit in the second fraction value is ~232 picosecond. E.g. example from the internet:

• we get value 1329481807 in the second fraction value from the server which is something like that 0.30954410484991967678070068359375
• if the seconds value is 123456497 we would get 123456497.30954410484991967678070068359375

Whatever your application requires, you are free to "strip" fraction value to milliseconds/microseconds by using your formulae:

let microseconds = time.sec_fraction() as u64 * 1_000_000 / u32::MAX as u64

For our example that would lead to something like that:

let seconds = time.sec() // 123456497
let fractions = time.sec_fraction() as f64 / u32::MAX as f64 // 0.30954410484991967678070068359375
let microsec_fractions = time.sec_fraction() as u64 * 1_000_000 / u32::MAX as u64 // 309544

println!("Got time: {}", seconds as f64 + fractions); // 123456497.30954410484991967678070068359375
println!("Got time: {}.{}", seconds, microsec_fractions); // 123456497.309544

[vpetrigo]

Should be fixed in 0.3.3+. Feel free to reopen that issue if your question is still unanswered. 😄