Re: 64 bit arithmetic?

[Colin D Bennett]

On Wed, 11 Jun 2008 00:54:35 +0800
Bean <address@hidden> wrote:

> On Wed, Jun 11, 2008 at 12:26 AM, Colin D Bennett <address@hidden>
> wrote:
> > I'm working on implementing a higher resolution timer using the x86
> > TSC.  However, this entails 64-bit arithmetic since on a 2GHz
> > machine it will overflow a 32-bit number every couple of seconds
> > (the TSC counter CPU cycles since boot).
> >
> > So to convert the TSC value into a value in milliseconds, I need to
> > do 64-bit division, but when I try to build GRUB now, I get
> >
> >   undefined reference to `__udivdi3'
> >
> > Is this expected?  Should it be possible for me to do division on
> > grub_uint64_t types?
> >
> > BTW, I'm trying to add it to the kernel image, if this makes a
> > difference.
> 
> Hi.
> 
> You can use grub_divmod64, which is defined in kern/misc.c

Thanks! That works perfectly.

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