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Date: Sun, 21 Sep 2014 20:01:08 +0400 (MSK)
From: Alexander Monakov <amonakov@...ras.ru>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] fix a bug in the rand48 family of prng
On Sun, 21 Sep 2014, Alexander Monakov wrote:
> UB on shift shouldn't be a problem here; I think the issue is that
> "lc[0] | lc[1]<<16" gets sign-extended rather than zero-extended from 32 bit
> to 64 bit.
(sorry, sent previous email too soon)
example code:
unsigned short a[3];
long long foo()
{
return a[0] | a[1] << 16 | a[2]+0ull<<32;
}
long long bar()
{
return a[0] | a[1]+0u << 16 | a[2]+0ull<<32;
}
Incidentally I think a "+0u" should suffice as a fix rather that "+0ull".
Alexander
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