[Mono-dev] [PATCH] eglib patch to avoid double overflow in win32 gtimers

[Miguel de Icaza]

Hello,

    Can you apply to both 2-4 and trunk?

> The calculation:
>     *microseconds = (gulong)(1000000.0 * (stop - timer->start) / freq);
> 
> isn't ideal ordering for long-running timers and may overflow after
> multiplying by 1000000.0 but before having a chance to divide by freq. A
> simple reordering of operations makes this less likely.
> 
> Also, I made it so that it only needs to query the performance counter
> frequency once rather than each time. The patch also handles errors
> getting the performance counter frequency (currently falls back to freq
> = 1, but perhaps it should use freq = 1000000? Does anyone have hardware
> where this actually fails?). This prevents possible divide-by-zero
> exceptions.
> 
> Jeff
> 
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