Re: Interfacing with C

[David Thompson <dave.thompson2@verizon.net>]

On Mon, 18 May 2009 13:58:35 +0200, "Dmitry A. Kazakov"
<mailbox@dmitry-kazakov.de> wrote:

> On Mon, 18 May 2009 04:29:44 -0700 (PDT), cedric wrote:

> > SPSSXD_API bool IsBackendReady();

>    with Interfaces.C;  use Interfaces.C;
>    ...
>    function IsBackendReady return Int; -- C does not have Boolean
>    pragma Import (stdcall, IsBackendReady, "IsBackendReady");
> 
C99 does, but that name is optional; _Bool always exists, but bool is
typedef'ed to it only if you #include <stdbool.h>. This was done to
preserve C90 (or earlier) code, where it is fairly common to typedef
bool to an integer or or enum type for documentation, even though it
doesn't change the actual semantics (and machine code). So it would be
necessary to determine which (or what) this code is using.

Though in practice, all integer types up to at least int/u-int are
often treated the same in the calling convention, so there's a fair
chance declaring it as Int=int will work even if it's really something
else including _Bool.