nanoseconds in units::Duration are truncated

[dkroenke]

Required information

Operating system:
on aarch64 targets like Raspberry PI

Compiler version:
E.g. GCC 9.3.0

Observed result or behaviour:
The Posix Timer is getting double values on the API which are then converted into int64_t internally. This conversion leads to a loss of data because the compiler will truncate the value. This can lead to abnormal behaviour when using small numbers like 1 nanoseconds.

Expected result or behaviour:
Remove the double literals from the posix timer API and expect only integer als time values. Then we avoid this constraint and have a clean calculation.

Conditions where it occurred / Performed steps:
Try to start a timer with 1 nanosecond waiting time. It will no execute because the time is internally set to zero. This disarms the timer and it is not proceeding.

[budrus]

I can confirm. But first lost some time with my Pi before finding this issue...

[elBoberido]

@dkroenke I think this related to the underlying long double of units::Duration. Should we rephrase this bug to fix the problem on its source?

@elfenpiff suggested in #337 to use

struct duration_t {
     uint64_t seconds;
     uint32_t nanoseconds;
};

as base instead of long double