Carefully check all scalar2's for argument order

[bunnie]

Two scalar2's were found to have argument orders flipped in the std re-implementation.

I have included the reference code from the Xous side, can you please check the code comments and see if you agree that the calls to SeekKeyStd and GetTimeUtcMs are flipped?

The other calls I just added lots and lots of comments around them.

[xobs]

It does look like GetTimeUtcMs has the opposite endianness to ElapsedMs, which is curious. That's a good find.

Interestingly, the SeekKeyStd calls appear to have been broken before the current patch:

rust/library/std/src/sys/xous/fs.rs

Lines 454 to 462 in c29037f

	SeekFrom::Start(off) => {
	(0, (off as usize & 0xffff_ffff), ((off >> 32) as usize) & 0xffff_ffff)
	}
	SeekFrom::Current(off) => {
	(1, (off as usize & 0xffff_ffff), ((off >> 32) as usize) & 0xffff_ffff)
	}
	SeekFrom::End(off) => {
	(2, (off as usize & 0xffff_ffff), ((off >> 32) as usize) & 0xffff_ffff)
	}

GetUtcTimeMs is broken in upstream Rust as well, and I'll have to submit a PR.

Would it be possible to get this as a series of patches instead of all in one patch? I'd like:

1. One patch that fixes GetUtcTimeMs so that I can submit it upstream in isolation
2. One patch to fix SeekKeyStd that I can squash into the existing pddb implementation
3. Remove the surrounding comments. They're handy for this sort of analysis, but their use diminishes once things are stable, and I don't know that I could get the changes merged upstream

If you prefer, I can take the changes and apply them myself.

[bunnie]

Hmm. Would another way to fix this possibly be to patch Xous to adopt the endianness used in the library? There's no way we're going back to the older libstd code bases, right?

[xobs]

Correct, we won't be going back to older libstd codebases.

It may make sense to at least patch Core so that SeekKeyStd is swapped around, since libstd has always used the "wrong" order.

As for GetUtcTimeMs, that's up to you. It's perfectly valid to swap it in Core, given that it's a monorepo!

[bunnie]

I'll close this PR, I've fixed the issues (I think) inside Xous itself.