Date: Fri, 7 Sep 2007 15:49:39 +0300 From: Giorgos Keramidas <keramida@ceid.upatras.gr> To: Luigi Rizzo <rizzo@icir.org> Cc: current@freebsd.org Subject: Re: how to tell 64 vs 32 bit architecture ? Message-ID: <20070907124938.GE3164@kobe.laptop> In-Reply-To: <20070907050310.A94579@xorpc.icir.org> References: <20070906111028.A83649@xorpc.icir.org> <20070906222647.GB2737@kobe.laptop> <20070907000950.A91211@xorpc.icir.org> <20070907115021.GA2718@kobe.laptop> <20070907050310.A94579@xorpc.icir.org>
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On 2007-09-07 05:03, Luigi Rizzo <rizzo@icir.org> wrote: >On Fri, Sep 07, 2007 at 02:50:21PM +0300, Giorgos Keramidas wrote: >>> i am actually looking at pointer sizes, as i need to do some pointer >>> manipulation going through intptr_t, and need to know that in the >>> preprocessor because some constants need to be 32 or 64 bit depending >>> on that, and are not trivial (i.e. not 0, 1 or something i can build >>> with size-agnostic expressions) >> >> An intptr_t can safely hold any void pointer value [..a.] >> What sort of manipulation? Can this sort of manipulation be written in >> a way that uses sizeof(intptr_t) instead of 4, 8, or preprocessor magic? > > i need to do this: > > #ifdef BUILT_FOR_64BIT_POINTERS > #define MY_MAGIC 0xdeadbeefd00de123 /* 64 bit */ > #else > #define MY_MAGIC 0xdeadbeef /* 32 bit */ > > If you know of a way to implement this without preprocessor > magic, i am all ears. If the values were simpler (eg all ones or so) > i could have used ~((unitptr_t)0) but this is not the case here You essentially want sizeof() at the preprocessor context. I don't think this is possible to write portably without preprocessor magic.
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