[Dune-devel] hash_combine on 32 bit

[Steffen Müthing]

Hi Carsten,


Am 21.10.2013 um 10:51 schrieb Carsten Gräser:

> Hi Steffen,
> I somehow didn't notice this before:
> 
> The new version of hash_combine() used a 47 bit shift on
> a size_t which issues a warning on 32 bit systems. At the
> respective function in the CityHash header you pointed
> to in the docs only uses uint64 instead.
> 
> Do you know if this 32 bit variant is still reasonable?

you're right, the code is probably not correct for 32bit systems. I have
a local patch with a 32bit version of the algorithm (also taken from
CityHash), but it depends on a test for the size of size_t, and I don't
know how to write that test for cmake. I've asked Christoph to take a
look at that. Once the test works for cmake as well, I'll push the fix.

Best,
Steffen

> 
> Best,
> Carsten
> 
> 
> -- 
> ----------------------------------------------------------------------
> Dr. Carsten Gräser       | phone: +49-30 / 838-75349
> Freie Universität Berlin | fax  : +49-30 / 838-54977
> Institut für Mathematik  | email: graeser at math.fu-berlin.de
> Arnimallee 6             |
> 14195 Berlin, Germany    | URL  : http://page.mi.fu-berlin.de/graeser
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> 
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