OCaml Int64 <-> C int64_t

OCaml Int64 <-> C int64_t

[Jianzhou Zhao]

Hi,

To convert between OCaml Int64 and C Integer, I think uint64_t or
int64_t can be the target C type. Int64_val is the macro converting
OCaml value to int64, I failed to find the macro for the other
direction under ./byterun. ./byterun/ints.c defines operations on
int64, caml_copy_int64(I64_of_intnat(..)) seems to be working for such
conversion? But mlvalues.h does not declare them to use. How can I
convert int64 to value?

Thanks
-- 
Jianzhou

Re: [Caml-list] OCaml Int64 <-> C int64_t

[Mathias Kende]

Le mercredi 18 août 2010 à 13:28 -0400, Jianzhou Zhao a écrit :
> But mlvalues.h does not declare them to use. How can I
> convert int64 to value?

caml_copy_int64 is declared in <caml/alloc.h>. There is no Val_int64
macro because int64 values are heap objects which must be allocated (the
Val_... macros are mostly just static_cast).

Mathias

Re: [Caml-list] OCaml Int64 <-> C int64_t

[Jianzhou Zhao]

On Wed, Aug 18, 2010 at 1:36 PM, Mathias Kende <mathias@kende.fr> wrote:
> Le mercredi 18 août 2010 à 13:28 -0400, Jianzhou Zhao a écrit :
>> But mlvalues.h does not declare them to use. How can I
>> convert int64 to value?
>
> caml_copy_int64 is declared in <caml/alloc.h>. There is no Val_int64
> macro because int64 values are heap objects which must be allocated (the
> Val_... macros are mostly just static_cast).

Does caml_copy_int64 do all I want?

int64_t C_fun();

CAMLprim value stub()
{
  return (caml_copy_int64 (C_fun()));
}

Do we still need I64_of_intnat? It is not included in <caml/alloc.h>
or other headers.

>
> Mathias
>
>



-- 
Jianzhou

Re: [Caml-list] OCaml Int64 <-> C int64_t

[Mathias Kende]

Le mercredi 18 août 2010 à 14:16 -0400, Jianzhou Zhao a écrit :
> Does caml_copy_int64 do all I want?

I believe so, but then I don't know what you want...

> 
> int64_t C_fun();
> 
> CAMLprim value stub()
> {
>   return (caml_copy_int64 (C_fun()));
> }
> 
> Do we still need I64_of_intnat? It is not included in <caml/alloc.h>
> or other headers.

INT64_of_intnat is an internal macro. There is no reason to use it. Your
snippet of code seems correct, but remember that caml_copy_int64 will
allocate values in the heap so you need to use the CAMLparam/CAMLreturn
macro if your function receives arguments from the caml world.