Possible way to define NAN so that it works in visual c++
#define INFINITY (DBL_MAX+DBL_MAX)
#define NAN (INFINITY-INFINITY)

Also gstcontrobinding.c uses isnan, which is C99. msvc would need _isnan

Thanks, I'll think about how to fix the API here. Most likely the controller will use a 0.0 - 1.0 value range (or -1.0 - 1.0) and then I can just use a large value. Or change the api to use a out-var and a gboolean return and tell that if the return value is FALSE the content of the out-var is undefined.

Well, NAN and isnan are slowly creeping into gstreamer in different places as well, maybe it wouldn't be a bad idea to have GST_NAN and gst_isnan...

Yep, its a good fit for ./gst/math-compat.h. I have found a coupld of isnan calls in gst-ffmpeg, but nowhere else so far. For linux I found a define for NAN in bits/nan.h (included from math.h). It is essentially:


# if __BYTE_ORDER == __BIG_ENDIAN
#  define __nan_bytes		{ 0x7f, 0xc0, 0, 0 }
# endif
# if __BYTE_ORDER == __LITTLE_ENDIAN
#  define __nan_bytes		{ 0, 0, 0xc0, 0x7f }
# endif

static union { unsigned char __c[4]; float __d; } __nan_union
    __attribute_used__ = { __nan_bytes };
# define NAN	(__nan_union.__d)

commit eba636cc8320f0eef860cda70577dc5257dd7ac7
Author: Stefan Sauer <ensonic@users.sf.net>
Date:   Fri Dec 30 13:32:18 2011 +0100

    controller: use NAN instead of FP_NAN (which is the class)
    
    Also add a fallback define to math-compat.h.
    Fixes #666887

Matej, would this be sufficient for isnan?

#ifndef isnan
#define isnan(f) _isnan(f)
#endif

Are you sure that isnan is a macro on all platforms?
from man page:
   In C90 mode, the isnan() function tests whether x is NaN.

   In C99 mode, the isnan() macro determines whether its  argu-
   ment  value is NaN. First, an argument represented in a for-
   mat wider than its semantic type is converted to its  seman-
   tic type. The determination is then based on the type of the
   argument.

perhaps we could have

#ifdef _MSC_VER
#define isnan(f) _isnan(f)
#endif

and similar checks for other platform that don't have native isnan.

Maybe this could also be done via __STDC_VERSION__ and/or _POSIX_VERSION checks like we do for rint etc.?