gettimeofday() always accessible?

Question

I've tried Google, php.net and the php mailinglist's archives, but I can't find what I'm looking for. Maybe it's obvious, or maybe nobody wonders about this...

For years, I've used microtime() to get the current time including the microseconds. However, somebody pointed me at a sentence in the manual page: "This function is only available on operating systems that support the gettimeofday() system call."

And PHP's gettimeofday() suggests the same situation: "This is an interface to gettimeofday(2)."

But... what kind of systems then don't have this system call available? Some googling around provided lots of C programmers trying to get a gettimeofday() implementation in C on Windows, since it doesn't seem to include it. But PHP's microtime() and gettimeofday() seem to work just fine on Windows (at least the boxes I could get to). Also, I just can't seem to find PHP code anywhere on the web that seems to check the existence of either microtime() or gettimeofday() before they call it, and there have to be lots of PHP programmers out there working on Windows boxes so...

Should I ignore the sentence in the manual and just trust that both functions are always available? Or is there another cross-platform way to get to the system time, including the microseconds, without using microtime() or gettimeofday()? Or will both functions just always exist, but just not give me microseconds if there is no gettimeofday() system call available?

EDIT 1:

http://www.php.net/microtime

"Returns the current Unix timestamp with microseconds.
This function is only available on operating systems that 
support the gettimeofday() system call."

Maybe this clarifies my point somewhat.

Answer 1

According to sources PHP has its own gettimeofday implementation for Windows. But there's no other ports of gettimeofday available. So except UNIX based systems and Windows, any other operating systems cannot use microtime()