Re: Pointer to int and vice versa

["Mark S. Waterbury" <mark.s.waterbury@xxxxxxxxxxxxx>]

Mihael:

This is precisely the problem of "storing a pointer in an integer."  
(Those macros "cast" a pointer to an integer and vice versa.)

Create your C modules, programs or service programs to run "teraspace 
enabled" and use only 64-bit pointers. That way, it is possible to 
"cast" an integer to a pointer and vice versa, and to store a pointer in 
an integer.

Use the ILE C compiler options DTAMDL(*LLP64) STGMDL(*TERASPACE) 
TERASPACE(*YES *TSIFC) on the CRTCMOD or CRTBNDC commands.

Hope that helps,

Mark S. Waterbury

> On 12/3/2010 5:04 AM, Schmidt, Mihael wrote:
> Hi,
>
> I am just in the process of (again) trying to port another C lib to the ILE environment. In C it seems common to return an integer via a pointer.
>
> #include<stdlib.h>
> #include<stdio.h>
>
> typedef int    gint;
> typedef unsigned int    guint;
> typedef void* gpointer;
> #define GPOINTER_TO_INT(p)    ((gint)   (p))
> #define GPOINTER_TO_UINT(p)    ((guint)  (p))
> #define GINT_TO_POINTER(i)    ((gpointer)  (i))
> #define GUINT_TO_POINTER(u)    ((gpointer)  (u))
>
>
> main ()
> {
>    gint x = 358;
>    gpointer p = GINT_TO_POINTER(x);
>    gint y = GPOINTER_TO_INT(p);
>    printf("%i", y);
> }
>
> Is this safe to do on IBM i as normally pointers are 16 bytes on IBM i instead of 4 bytes as on most PC Systems.
>
> (The question is not about storing a pointer in an integer as I know that this is not possible because of the size differences.)
>
> Regards
>
> Mihael Schmidt
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