Re: PATCH: prevent SIGFPE on systems where LONG_MIN < -LONG_MAX

[Peter Stephenson <Peter.Stephenson@xxxxxxx>]

On Mon, 3 Sep 2012 16:40:37 +0200
Mikael Magnusson <mikachu@xxxxxxxxx> wrote:
> See also this thread,
> http://www.zsh.org/mla/workers/2011/msg00613.html
> 
> On 03/09/2012, Jérémie Roquet <arkanosis@xxxxxxxxx> wrote:
> > Hello,
> >
> > $ echo $[ - 2**63 / -1 ]
> > zsh: floating point exception  ./Src/zsh
> >
> > $ echo $[ - 2**63 % -1 ]
> > zsh: floating point exception  ./Src/zsh
> >
> > The attached patch fixes this.
> 
> 
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So what's the answer, then?  Jérémie's patch makes only limited
assumptions; I think the #if is there simply to see if we can assume
two's complement arithmetic (it seems the preprocessor isn't keen on
"#if LONG_MIN - 1 == LONG_MAX", I suppose it's not required to use
"long" precision) in which case the test should work.  It might not
cover all real cases, but that's a lesser evil.

-- 
Peter Stephenson <pws@xxxxxxx>            Software Engineer
Tel: +44 (0)1223 692070                   Cambridge Silicon Radio Limited
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