unsigned word type in OCaml?

unsigned word type in OCaml?

[Sussillo, David]

Hello,

I'm working on a low level systems project, and I'm thinking about using   
OCaml as the langauge.  However, try as I might, I simply cannot find a   
reference to a machine word type.

More specially, I need:
a. byte access to machine words
b. unsigned 32 bit quantities (e.g. physical address)
c. bitwise boolean operations (shifts, not, and & or)

Have I missed something either in the mailing list or the documentation?   
 What about (yuk) storing my OCaml words as strings and then  passing   
these strings to C and operating on them there? Wouldn't be great, but   
maybe a it's a temporary solution.

Thanks,
dave   

Re: unsigned word type in OCaml?

[Jean-Christophe Filliatre]

> I'm working on a low level systems project, and I'm thinking about using   
> OCaml as the langauge.  However, try as I might, I simply cannot find a   
> reference to a machine word type.
> 
> More specially, I need:
> a. byte access to machine words
> b. unsigned 32 bit quantities (e.g. physical address)
> c. bitwise boolean operations (shifts, not, and & or)

One year ago, I wrote a small (boxed) 32-bit integers library for
ocaml, which is freely available here :

       http://www.lri.fr/~filliatr/ftp/ocaml/int32/

It provides the standard operations, including bitwise boolean operations.
It is easy to adapt it to unsigned 32-bit integers.

-- 
Jean-Christophe FILLIATRE
  mailto:Jean-Christophe.Filliatre@lri.fr
  http://www.lri.fr/~filliatr

Re: unsigned word type in OCaml?

[Xavier Leroy]

> I'm working on a low level systems project, and I'm thinking about using   
> OCaml as the langauge.  However, try as I might, I simply cannot find a   
> reference to a machine word type.
> 
> More specially, I need:
> a. byte access to machine words
> b. unsigned 32 bit quantities (e.g. physical address)
> c. bitwise boolean operations (shifts, not, and & or)

None of this is supported natively in the language (OCaml's "int" type
and its associated operations is 31 or 63 bits, signed).

However, it's easy to define your "machine word" type as an abstract
type and implement it via small C functions.

Jean-Christophe Filliatre's "int32" library is a good starting point:

        http://pauillac.inria.fr/caml/caml-list/0200.html
        http://www.ens-lyon.fr/~jcfillia/ftp/ocaml/int32

Regards,

- Xavier Leroy