On Tue, Sep 13, 2011 at 4:37 AM, Liam Healy <l...@healy.washington.dc.us> wrote: > So I changed my approach, and in the process simplified the code a > lot. Instead of making the necessary libffi-type in the defcstruct > expansion, it will be made on demand only, when a foreign struct is > used by, e.g. defcfun. This happens recursively, so if one structure > uses another, both will be made. Once they structure is made, it is > attached to the plist of the symbol for the type, so it need not be > recomputed.
That makes sense. > I'm now dealing with built-in types and coming up against a problem > I've struggled with before (in GSLL and Antik): how to map C types > (:short, :int, etc.) into established byte sizes (:uint8, :uint16). > The problem is that libffi defines the types by their size, and it's > up to the user to figure out how to map the common C types to those > sizes; this is a topic in C that has always confused me. I notice > that CFFI has a mapping in the code at the end of src/types.lisp, but > it's not easily accessible to other code, so I think if I break that > out as some kind of table it will be useful to generate the > appropriate pointers for libffi. Unless someone has a better way. You can use FOREIGN-TYPE-SIZE (like the code you mention does), or you can pass the various :[u]intx types to CFFI::FOLLOW-TYPEDEFS and what they boil down to. Cheers, -- Luís Oliveira http://r42.eu/~luis/ _______________________________________________ cffi-devel mailing list cffi-devel@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/cffi-devel
