Re: [ANN] LuaProfiler 2.0

[Glenn Maynard <glenn@...>]

On Tue, Jun 14, 2005 at 05:19:49PM -0700, Chris Marrin wrote:
> I have gotten recent experience with QueryPerformanceCounter(). I 
> naively tried to get its value and divide it by the value in 
> QueryPerformanceFrequency(), first converting both to doubles. I found 
> that this conversion reduced the precision down to about 100ms. This is 
> because on my shiny new 3GHz P4 machine, the frequency is 3GHz! That 
> means the counter increments by 3 billion every second. Since it's a 64 
> bit counter it will still not rollover for about 200 years. But if your 
> machine has been running for a month or so like mine was, the number 
> gets too big to be represented very precisely by a double!

Stick with 64-bit integer math.  If you want microseconds:

	__int64 n = 10000000000ll;
	__int64 divisor = 3000000000ll;
	__int64 precision = 1000000;
	__int64 result = n * precision / divisor;


> -- 
> chris marrin                ,""$,
> chris@marrin.com          b`    $                             ,,.
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>  b$`             ,$: :,`` |$$      ,`   $$` ,|` ,$$,,`"$$     .`    :$|
> b$|            _m$`,:`    :$1   ,`     ,$Pm|`    `    :$$,..;"'     |$:
> P$b,      _;b$$b$1"       |$$ ,`      ,$$"             ``'          $$
>  ```"```'"    `"`         `""`        ""`                          ,P`
> "As a general rule,don't solve puzzles that open portals to Hell"'

Could you please use a more reasonable sig?  Four or five lines is more
than enough.

-- 
Glenn Maynard