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From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
To: RW <rwmaillists@googlemail.com>
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Date: Thu, 27 Sep 2012 16:34:23 +0200
In-Reply-To: <20120927125956.0594fa73@gumby.homeunix.com> (RW's message of
	"Thu, 27 Sep 2012 12:59:56 +0100")
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Cc: freebsd-security@freebsd.org
Subject: Re: Collecting entropy from device_attach() times.
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RW <rwmaillists@googlemail.com> writes:
> static __inline uint64_t
> get_cyclecount(void)
> {
>         struct bintime bt;
>
>         binuptime(&bt);
>         return (bt.frac ^ bt.sec);
>=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
> }

Why the heck does it xor the integer and fractional parts together?
That makes no sense at all.  I would have used ((uint64_t)bt.sec << 32 |
bt.frac >> 32).  It wraps around after 136 years' uptime, but hey, you
can't win them all.

DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no