Re: [Guile-commits] GNU Guile branch, master, updated. 782a82eed13abb64393f7acad92758ae191ce509

[Andy Wingo <wingo@pobox.com>]

Heya,

On Sat 06 Jun 2009 16:31, ludo@gnu.org (Ludovic Courtès) writes:

> Hello,
>
> "Andy Wingo" <wingo@pobox.com> writes:
>
>> +SCM_DEFINE (scm_uniform_array_to_bytevector, "uniform-array->bytevector",
>> +            1, 0, 0, (SCM array),
>> +	    "Return a newly allocated bytevector whose contents\n"
>> +            "will be copied from the uniform array @var{array}.")
>> +#define FUNC_NAME s_scm_uniform_array_to_bytevector
>> +{
>> +  SCM contents, ret;
>> +  size_t len;
>> +  scm_t_array_handle h;
>> +  const void *base;
>> +  size_t sz;
>> +  
>> +  contents = scm_array_contents (array, SCM_BOOL_T);
>> +  if (scm_is_false (contents))
>> +    scm_wrong_type_arg_msg (FUNC_NAME, 0, array, "uniform contiguous array");
>> +
>> +  scm_array_get_handle (contents, &h);
>> +
>> +  base = scm_array_handle_uniform_elements (&h);
>> +  len = h.dims->inc * (h.dims->ubnd - h.dims->lbnd + 1);
>> +  sz = scm_array_handle_uniform_element_size (&h);
>> +
>> +  ret = make_bytevector (len * sz);
>> +  memcpy (SCM_BYTEVECTOR_CONTENTS (ret), base, len * sz);
>
> Is this memcpy valid in the case of shared arrays?  Looks like we end up
> copying more elements than needed, but maybe it's better this way.

I'm not entirely sure. I thought that scm_array_contents will give me a
contiguous array, though trolling around in srfi-4.[ch] and unif.[ch]
makes me grumpy ;)

>> +           uniform-array->bytevector
>
> I would not export it from `(rnrs bytevector)' given that it has nothing
> to do with RnRS.

No, but it does have to with bytevectors... Where would you put it?

> Also, I would make the new C functions private, given that they are not
> intended for general use AIUI.

Dunno. I could imagine calling both of them from C. Would there be a
problem with leaving them to be public?

Cheers,

Andy
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