From: Kurt Dresner <omega697@...>
Date: 2004-11-23T04:09:08+09:00
Subject: Re: SWIG and Arrays (of ints)

Here are the actual functions I need to wrap:


/* This one allocates a cmac, which is the thing I'm going to be
using.  I tell it how many
 * states it has, how many responses it has, and some other
parameters.  The typemap you
 * provided I think will work rather well for this function.
 */
int allocate_cmac(int num_state, int *qnt_state,
			 int num_resp, int num_cell,
			 int memory, int rfield_shape,
			 int collision_flag);

/* With this function, I provide the ID of the cmac that was returned
to me in the allocate
 * function.  I then provide two arrays: the input states and the
desired responses.  These
 * have to be of the sizes num_state and num_resp from the last
function.  I think a similar
 * typemap will work just fine, since the C code presumably knows the
size of the arrays.
 * I just won't provide it.
 */
int train_cmac(int cmac_id, int *state, int *respns, int beta1, int beta2);

/* This is the one I'm stuck on.  I need to provide the ID, which will
work, and then an array
 * of state ints.  That will work too, as in the last one.  Now,
however, I need to provide
 * an array for the response.  This array is then filled up with the
response.  Two things are
 * confusing me.  I should probably do some sort of argout so I can
get both the int
 * (success/failure) return value (which I can probably map to
true/nil right?) and the array
 * return value.  The thing is, I don't know how to get it to create a
Ruby array for this
 * return value, since in the interface code, I don't know how big the
array is.  The C code
 * knows (presumably - I didn't write it).  So I don't know how to
write the argout to take care
 * of it.  I have no idea what to do with this.
 */
int cmac_response(int cmac_id, int *state, int *respns);

Any ideas?

-Kurt



On Sun, 21 Nov 2004 22:58:07 +0900, Tobias Peters
<tpeters@invalid.uni-oldenburg.de> wrote:
> Kurt Dresner wrote:
> 
> 
> > Hi all,
> >
> > I'm trying to get SWIG to create a wrapper for some C code.
> > Specifically, there are several functions that take, as parameters, an
> > int* (they also take the length of the array).  I don't know how to do
> > the typemap for this - I want to be able to write
> >
> > My_module.my_c_function([1,2,3])
> >
> > for the corresponding C function
> >
> > void my_c_function(int size, int* ary)
> >
> > Additionally, one of the functions takes an integer array as a
> > parameter, and I'd like it instead to return an array in Ruby (full of
> > Nums).  I know how to get it to return the argument (instead of doing
> > the pointer passing thing), but then it just thinks I want to pass it
> > an integer instead of an array of integers.
> >
> > Anyone have any idea how to help me? Everything I've seen pertains to
> > char** and I'm not sure how to convert it to work how I want with
> > int*.
> 
> Passing an array of integers from Ruby to C with SWIG requires
> multi-argument "in" and "freearg" typemaps:
> 
> %typemap(ruby,in) (int size, int *ary) {
>    int i;
>    if (!rb_obj_is_kind_of($input,rb_cArray))
>      rb_raise(rb_eArgError, "Expected Array of Integers");
>    $1 = RARRAY($input)->len;
>    $2 = malloc($1*sizeof(int));
>    for (i=0; i<$1; ++i)
>      ($2)[i] = NUM2INT(RARRAY($input)->ptr[i]);
> }
> %typemap(freearg) (int size, int *ary) {
>     if ($2) free($2);
> }
> 
> There's room for improvement in handling (or better: preventing)
> exceptions raised from NUM2INT (proper error message and deallocation of
> C array).
> 
> Regarding output: It's not clear to me if you want in/out semantics or
> output only. I think you can achieve in/out with an additional
> multi-argument "argout" typemap. Output only implementation depends on
> which function is responsible for allocating/freeing the array and which
> is responsible for determining the array's size. You may need an
> additional "arginit" typemap for this one.
> 
>    Tobias
> 
>