From: erik quanstrom <quanstro@quanstro.net>
To: 9fans@9fans.net
Subject: Re: [9fans] 5c ulong/vlong -> float64 bug
Date: Tue, 26 Oct 2010 22:26:11 -0400 [thread overview]
Message-ID: <8be5d1c88a9674013546b111628b414e@plug.quanstro.net> (raw)
In-Reply-To: <AANLkTikJ0+EWJFKui1=_cB5kOq8EeBCjY00nSV7cb5cV@mail.gmail.com>
On Tue Oct 26 22:13:45 EDT 2010, rsc@swtch.com wrote:
> For those people using 5c, I found a bug recently in the
> conversion of ulong to float64. The bug is that it's not
> implemented at all; instead 5c uses the long to float64 code,
> so converting 0x80000000 produces -2^31 not 2^31.
> This matters in _v2d, which uses it to convert vlong to float64.
> If the low 32 bits of the vlong have the high bit set,
> the conversion ends up off by 2^32.
>
> http://codereview.appspot.com/2726041 has a
> straightforward but perhaps inefficient fix.
already reported here with fix:
http://9fans.net/archive/2010/09/334
- erik
prev parent reply other threads:[~2010-10-27 2:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-27 2:12 Russ Cox
2010-10-27 2:26 ` erik quanstrom [this message]
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