[m-rev.] for review: implement is_nan/1 and is_inf/1 for MSVC

[Peter Wang]

On Fri, 31 May 2013 16:56:21 +1000 (EST), Julien Fischer <jfischer at opturion.com> wrote:
> 
> For review by anyone.
> 
> Branches: 13.05, master
> 
> -------------------
> 
> Implement is_nan/1 and is_inf/1 installations using MSVC.
> 
> runtime/mercury_float.c:
>  	Provide MSVC specific definitions for MR_is_nan
>  	and MR_is_inf.
> 
> Julien.
> 
> diff --git a/NEWS b/NEWS
> index 1f50052..8ba2bd7 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -20,6 +20,8 @@ This is a bug-fix release.
>     (Bug #257)
>   * A bug that caused a compiler abort in the low-level C backend has been
>     fixed.
> +* The functions float.is_nan/1 and float.is_inf/1 now work when using
> +  Microsoft Visual C++ as the C compiler.
> 
>   Changes to the Mercury standard library:
> 

Did the fallbacks not work before?

> diff --git a/runtime/mercury_float.c b/runtime/mercury_float.c
> index 798cc30..49d319e 100644
> --- a/runtime/mercury_float.c
> +++ b/runtime/mercury_float.c
> @@ -111,6 +111,8 @@ MR_is_nan(MR_Float Flt)
>       return isnanf(Flt);
>   #elif defined(MR_HAVE_ISNAN)
>       return isnan(Flt);
> +#elif defined(MR_MSVC)
> +    return _isnan(Flt);
>   #else
>       return (Flt != Flt);
>   #endif
> @@ -130,6 +132,10 @@ MR_is_inf(MR_Float Flt)
>       return isinf(Flt);
>   #elif defined(MR_HAVE_FINITE)
>       return !finite(Flt) && (Flt == Flt);
> +#elif defined(MR_MSVC)
> +    int sw;
> +    sw = _fpclassify(Flt);
> +    return (sw == _FPCLASS_NINF) || (sw == _FPCLASS_INF);

What does sw stand for?

Looks fine otherwise.

Peter