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Re: cross-platform thread-safe RNG drand48_r
- From: Ian Lance Taylor <iant at google dot com>
- To: Qianqian Fang <fangqq at gmail dot com>
- Cc: gcc-help at gcc dot gnu dot org
- Date: Sun, 06 Jun 2010 20:37:00 -0700
- Subject: Re: cross-platform thread-safe RNG drand48_r
- References: <4C0C2C45.6010608@gmail.com>
Qianqian Fang <fangqq@gmail.com> writes:
> I was trying to compile a simulation code on
> multiple platforms. It involves a thread-safe
> 48bit POSIX random number generator (RNG),
> drand48_r/seed48_r. I tried gcc 4.4 on Ubuntu
> 10.4 and it compiled fine. However, when
> I run gcc 4.0 on Mac OS X, it gave me error:
>
> posix_randr.h:29: error: array type has incomplete element type
>
> and the offending lines read like:
>
> typedef struct drand48_data RandType;
> __device__ float rand_uniform01(RandType t[RAND_BUF_LEN]);
> ...
>
> Similar error when compiling on Windows with
> MinGW gcc 3.4.
>
> Because drand48 is supposed to be a POSIX function,
> I am a bit surprised when seeing multiple platforms
> responded differently. Did I miss anything? or
> this is the correct behavior?
As far as I know drand48 is not in POSIX. It's in the SVID and it's
in X/Open, but I don't think it's in POSIX proper. And as far as I
know drand48_r is just a GNU extension to drand48. But it's certainly
possible that POSIX picked this up somewhere.
In any case, this sounds like a bug, but it sounds like a library bug;
it doesn't sound like a compiler bug.
Ian