From: Julius Schmidt <aiju@phicode.de>
To: 9front@9front.org
Subject: replacing rand()
Date: Sat, 10 Sep 2016 12:34:58 +0200 (CEST) [thread overview]
Message-ID: <alpine.LNX.2.00.1609101118350.6016@phi> (raw)
An infuriating discussion with martian67 this morning has reminded me
to run statistical tests on our rand(). As expected, it doesn't perform
too well (fails 9/15 SmallCrush, BigCrush still running, fails after 256
MB of PractRand). I'm wondering whether we should replace with rand()
with something better as RNGs exist nowadays that are both simpler,
faster and produce better random numbers.
I would propose xoroshiro128+:
u64int state0, state1;
u64int
llrand(void)
{
u64int s0, s1, r;
s0 = state0;
s1 = state1;
r = s0 + s1;
s1 ^= s0;
state0 = (s0 << 55 | s0 >> 9) ^ s1 ^ (s1 << 14);
state1 = (s1 << 36 | s0 >> 28);
return r;
}
http://xoroshiro.di.unimi.it/xoroshiro128plus.c
next reply other threads:[~2016-09-10 10:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-10 10:34 Julius Schmidt [this message]
2016-09-10 12:30 ` [9front] " Julius Schmidt
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