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Extending a list on the OCAML side that is initially allocated on the C side
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Date: -- (:)
From: nari <nari@i...>
Subject: Extending a list on the OCAML side that is initially allocated on the C side

I have an OCAML and C function as follows

**************OCAML side*****************
let simple_list_test m = m @ [100]
let _ =
   Callback.register "simple_list_test" simple_list_test;

*************C side***********************
main(int argc, char *argv[])
    int *list, *new_list;

    fprintf (stderr,"Initializing OCAML\n");
   fprintf (stderr,"Initializing OCAML Done\n");
   list = (int *) calloc(10, sizeof(int));
   new_list = call_caml_simple_list_test(list);
/* I expect eleven elements in list after the call to ocaml and expect
     to be printed out */
   printf("The last element is %d\n", new_list[10]);

int * call_caml_simple_list_test(int *list)
   static value * closure_f = NULL;
   value ret_val;

      if (closure_f == NULL) {
         closure_f = caml_named_value("simple_list_test");
   ret_val = callback(*closure_f, (value) list);
   return (int *)ret_val;
**********************End C side*****************

My understanding (from documentation) is that since "list" is allocated
on the "C" side, it is outside the heap of the ocaml garbage collector
all I have to do is to cast the pointer to a caml 'value' type.
I get a core dump (segmentation fault) with the above code.
How can I modify or extend the list (or for that matter, any record)
on the OCAML side and then send the C side back a pointer that I can

Narayanan Krishnamurthy (Nari)
The Somerset PowerPC Design Center,
Architecture and Systems Platforms
Motorola Inc. Semiconductor Products Sector
7700 W. Parmer Lane, Austin, TX 78729

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