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This commit is contained in:
Robin Müller 2024-03-18 14:21:24 +01:00
parent 8161e59ba1
commit 247cc72753
Signed by: muellerr
GPG Key ID: A649FB78196E3849
1 changed files with 16 additions and 8 deletions
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24
src/time/cuc.rs
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@ -156,8 +156,10 @@ pub struct FractionalPart(FractionalResolution, u32);
/// It has the capability to generate and read timestamps as specified in the CCSDS 301.0-B-4
/// section 3.2 . The preamble field only has one byte, which allows a time code representation
/// through the year 2094. The time is represented as a simple binary counter starting from the
/// fixed CCSDS epoch (1958-01-01T00:00:00+00:00). It is possible to provide subsecond accuracy
/// using the fractional field with various available [resolutions][FractionalResolution].
/// fixed CCSDS epoch 1958-01-01T00:00:00+00:00 using the TAI reference time scale. This time
/// code provides the advantage of being truly monotonic.
/// It is possible to provide subsecond accuracy using the fractional field with various available
/// [resolutions][FractionalResolution].
///
/// Having a preamble field of one byte limits the width of the counter
/// type (generally seconds) to 4 bytes and the width of the fractions type to 3 bytes. This limits
@ -167,6 +169,9 @@ pub struct FractionalPart(FractionalResolution, u32);
/// leap seconds corrections need to be applied to support the trait methods. Instead, it needs
/// to be converted to a [CucTimeWithLeapSecs] object using the [Self::to_leap_sec_helper] method.
///
/// This time code is not UTC based. Conversion to UTC based times, for example a UNIX timestamp,
/// can be performed by subtracting the current number of leap seconds.
///
/// # Example
///
/// ```
@ -361,13 +366,18 @@ impl CucTime {
res: FractionalResolution,
leap_seconds: u32,
) -> Result<Self, TimestampError> {
let mut counter = unix_epoch_to_ccsds_epoch(unix_stamp.secs);
let counter = unix_epoch_to_ccsds_epoch(unix_stamp.secs);
// Negative CCSDS epoch is invalid.
if counter < 0 {
return Err(TimestampError::DateBeforeCcsdsEpoch(*unix_stamp));
}
// We already excluded negative values, so the conversion to u64 should always work.
let mut counter = u32::try_from(counter).map_err(|_| CucError::InvalidCounter {
width: 4,
counter: counter as u64,
})?;
counter = counter
.checked_add(i64::from(leap_seconds))
.checked_add(leap_seconds)
.ok_or(TimestampError::Cuc(CucError::LeapSecondCorrectionError))?;
let fractions =
fractional_part_from_subsec_ns(res, unix_stamp.subsec_millis() as u64 * 10_u64.pow(6));
@ -435,7 +445,7 @@ impl CucTime {
if counter.1 > (2u64.pow(counter.0 as u32 * 8) - 1) as u32 {
return Err(CucError::InvalidCounter {
width: counter.0,
counter: counter.1 as u64,
counter: counter.1.into(),
});
}
if let Some(fractions) = fractions {
@ -704,9 +714,7 @@ impl CcsdsTimeProvider for CucTimeWithLeapSecs {
}
fn unix_secs(&self) -> i64 {
ccsds_epoch_to_unix_epoch(self.time.counter.1 as i64)
.checked_sub(self.leap_seconds as i64)
.unwrap()
self.time.unix_secs(self.leap_seconds)
}
fn subsec_nanos(&self) -> u32 {