Re: [Caml-list] detecting 32/64 bit from C

[Adrien Nader <adrien@notk.org>]

On Tue, Oct 13, 2015, Markus Weißmann wrote:
> Hello,
> 
> is there some "official" way to detect -- from C -- if OCaml was
> compiled for 32 or 64 bit?
> I'd love to have something like a #define that either says 32 or 64
> bit;
> I need to know at compile time if the OCaml system uses 31 or 63 bit
> sized integers (in the C code).
> I don't care what the underlying OS or hardware does, but just what
> OCaml is using.
> 
> Btw.: Is [Sys.word_size = 32] for 32 bit OCaml compilers on 64 bit
> machines?

Hi,

I believe config.h has the info you want:
  #define ARCH_SIXTYFOUR // for instance

Note how it's installed under $(libdir) and not $(includedir): its
content is set at configure-time and depends on the architecture that
ocaml has been configured for.

-- 
Adrien Nader