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Re: 64 bit arithmetic?

From: Bean
Subject: Re: 64 bit arithmetic?
Date: Wed, 11 Jun 2008 00:54:35 +0800

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.


You can use grub_divmod64, which is defined in kern/misc.c


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