Newsgroups: comp.os.msdos.programmer,comp.os.msdos.djgpp
From: manni DOT heumann AT gmx DOT de (Manni Heumann)
Subject: Re: Uptime and entropy in DOS
Distribution: world
References: <lra6ascbh1fu2d4738d44h09kpooc8ecta AT 4ax DOT com> <38A5583C DOT EDF375B4 AT is DOT elta DOT co DOT il> <591baskf2ns6u0n0l6kp8rgml7aa2q80la AT 4ax DOT com>
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Date: Sat, 12 Feb 2000 18:13:37 GMT
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

In article <591baskf2ns6u0n0l6kp8rgml7aa2q80la AT 4ax DOT com>, REPLYTOd_yerrick AT hotmail DOT comNO2CANNEDHAM wrote:
>On Sat, 12 Feb 2000 14:55:24 +0200, Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
>wrote:
>
>>Damian Yerrick wrote:
>>> 
>>> Is it possible to get the uptime of a DOS system?  I need more entropy
>>> than the 32 bits I get from time(NULL) to initialize a pseudorandom
>>> number generator.
>>
>>Did you try `uclock' or `gettiomeofday'?  It's in the FAQ (section 22.23).
>
>uclock() won't work because it measures uptime of the current process,
>which is *known* when the process starts, which is when I seed my PRNG
>and start Allegro.  And because Allegro reprograms the timer, I can't
>reseed from uclock() after the program starts.
>
>gettimeofday() won't work because it in theory can be calculated from
>time(NULL), which I'm already using, and adds no entropy.
>

I'm nosy: Why isn't all of this enough for you?
What about the user? How about a "Any key to continue" message and you measure 
the time it takes to answer that one and then combine it with time (NULL).


--

Manni