[Cfp-interest] FUNCTIONS - outline updated

[Jim Thomas]

Fred J. Tydeman wrote:

...

>
>As I recall, the issignalling() function takes a
>floating-point type.  That implies to me that the
>normal function calling sequence will be used.  My
>understanding is some implementations would trigger
>the SNaN doing the function call.  I think this
>function needs a pointer to floating-point type.
>  
>
Good point. I was thinking of issignaling as a macro, like the other 
inquiry macros (isnan, etc.). However, for some implementations it might 
still be difficult to implement without triggering a signal, unless the 
compiler does special stuff (more than required for other inquiry 
macros). Special compiler stuff would probably be needed for a macro 
with pointer to floating-point type too. Easiest to implement would be 
functions with a parameter that's a pointer to the floating-point type, 
e.g.,

int issignalingf(const float * xp);

This would be a bit worrisome because the issignaling name (at least for 
double) looks like an inquiry macro but it's not.

Ease of implementation isn't usually a weighty consideration, but 
signaling NaNs will muck up everything if we let them.

-Jim