[cffi-devel] [feature request] array type
Hello! Has there been any more thought put into the possibility of defining an array type? Having read the list archives, I'm aware that this has been proposed: http://common-lisp.net/pipermail/cffi-devel/2005-September/000057.html I can certainly help test on various Lisp implementations, and with some guidance into how types are defined in CFFI, I'm willing to contribute some patches. Thanks. -- Jack Unrue
Jack Unrue <jdunrue@gmail.com> writes:
Hello! Has there been any more thought put into the possibility of defining an array type? Having read the list archives, I'm aware that this has been proposed:
Hello, Can you give me an example usage of such type or an example that shows how the current array support is insufficient? Thanks, -- Luís Oliveira luismbo (@) gmail (.) com Equipa Portuguesa do Translation Project http://www.iro.umontreal.ca/translation/registry.cgi?team=pt
Hello,
Can you give me an example usage of such type or an example that shows how the current array support is insufficient?
Thanks, Luís. I may be misunderstanding what array support is already present. I'm looking for basically what you proposed in your reply to: http://common-lisp.net/pipermail/cffi-devel/2005-September/000058.html My goal is simply to declare structs whose C equivalent includes array members. I'm not sure how the array declaration would be done in CFFI so I'll use LispWorks FLI instead: (fli:define-c-struct foo (data (:c-array :int 32)) (id :int)) would correspond to struct foo { int data[32]; int id; }; such that allocating an instance of foo on the Lisp side could be accomplished without having to separately allocate the data array. In LispWorks, I would use fli:with-dynamic-foreign-objects to allocate a temporary instance of foo. A real example of how I would use this is the Win32 BeginPaint function which populates a supplied pointer to a PAINTSTRUCT (which has a 32 byte array as the last member). Thanks again, and if RTFM is the answer, please do point me in the right direction :-) -- Jack Unrue
On 2005-dec-11, at 06:48, Jack Unrue wrote:
My goal is simply to declare structs whose C equivalent includes array members. I'm not sure how the array declaration would be done in CFFI so I'll use LispWorks FLI instead:
(fli:define-c-struct foo (data (:c-array :int 32)) (id :int))
This would translate to: (cffi:defcstruct foo (data :int :count 32) (id :int)) The plan is that you would access an element of this array using (cffi:foreign-slot-value foo-obj 'foo 'data <index>). However, this is not implemented yet so, for the time being, you'll need to use something like: (cffi:mem-aref (cffi:foreign-slot-value foo-obj 'foo 'data) :int <index>) Or: (cffi:with-foreign-slots ((data) foo-obj foo) (cffi:mem-aref data :int <index>)) This is not to say that an array type is not needed. I think we'll need one in order to access multi-dimensional arrays conveniently. -- Luís Oliveira http://student.dei.uc.pt/~lmoliv/ Equipa Portuguesa do Translation Project http://www.iro.umontreal.ca/translation/registry.cgi?team=pt
On 12/11/05, Luís Oliveira <luismbo@gmail.com> wrote:
This would translate to:
(cffi:defcstruct foo (data :int :count 32) (id :int))
Many thanks, that's what I was missing. And also thanks for the info about mem-aref. -- Jack Unrue
participants (2)
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Jack Unrue -
Luís Oliveira