hedgehog

From my distant past I seem to recall that unix calculated it's time and date by counting seconds from some fixed point in the past, in 1974 or something.

Does anyone know if the C code for this calculation is available as I need to use something similar in a microcontroller and am stuffed if I know how to write it. I'm also too lazy to write it myself if it's already been done :-)

I'd be grateful for any help or suggestions, even pointers to similar code.

Thanks,
Philip.

michael_clarkson

The Unix EPOCH time is simply the number of seconds since 1/1/1970. This should be a simple calculation

Just found these, do these help ?

http://www.lovelady.com/unix-source.html

Michael

[Edited by michael_clarkson - 11/13/2003 8:53:49 PM]

[Edited by michael_clarkson - 11/13/2003 8:54:34 PM]

chiark

STFW

stevencotton

It's so so easy, your implementation will already provide a method/function for returning epoch seconds.

hedgehog

Thanks for that folks, I think that unix source site will do the job for me. The thing I didn't want to get into was calculating the date and time from the epoch seconds, I'm sure there is probably a simple formula but with leap years, some months having 30 days and others 31 etc. it looked like a pain to me. It's literally 17 years since I've written any C, or code of any type, so this doesn't fill me with joy! I also know nothing at all about microcontrollers. Luckily it's not an air traffic control centre I'm building :-)

Let's hope the cross compiler for the microcontroller has the header files to do all that time stuff, otherwise I will have to get a header file from somewhere and find out what the formula is :-)

Thanks again.

stevencotton

As long as there's a time.h and an strftime (I don't know about your cross-compiler but they're standard) then you'll be fine. You don't need to do any of the actual calculations yourself.

Miles

I wonder what will happen in 2040?

NotoriousREV

People will make lots of money in the run up to 2040 by certifying stuff Y2.04K compliant

*wanders off to register Y2.04K Ltd.*