CFFI question
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From: serg on 15 Apr 2010 10:22 Hello, part of C library looks like: typedef struct some_struct { . . . } some_struct; int func_1(some_struct **ic_ptr); int func_2(some_struct *ic); There are appropriate CL cffi descriptions: (cffi:defcstruct some-struct . . . ) (cffi:defcfun ("func_1" func-1) :int (ic-ptr :pointer)) (cffi:defcfun ("func_2" func-2) :int (ic :pointer)) Provided the necessary parts are loaded in image how could next C statements expressed in CL? some_struct *p; func_1(&p); func_2(p); -- Regards, Serg --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: Stelian Ionescu on 15 Apr 2010 13:27
On Thu, 15 Apr 2010 17:22:55 +0300, serg wrote: > Hello, > > part of C library looks like: > > typedef struct some_struct { > . . . > } some_struct; > > int func_1(some_struct **ic_ptr); > > int func_2(some_struct *ic); > > > There are appropriate CL cffi descriptions: > > (cffi:defcstruct some-struct > . . . > ) > > (cffi:defcfun ("func_1" func-1) :int > (ic-ptr :pointer)) > > (cffi:defcfun ("func_2" func-2) :int > (ic :pointer)) > > > Provided the necessary parts are loaded in image how could next C > statements expressed in CL? > > some_struct *p; > > func_1(&p); > func_2(p); What you need to keep in mind is that there's no «&» in CFFI, but only «*»; therefore you need to change your code to this style: some_struct **p = alloca(sizeof(some_struct *)); func_1(p); func_2(*p); so: (with-foreign-object (p :pointer) (func-1 p) (func-2 (mem-ref p :pointer))) just like alloca, with-foreign-object allocated the pointer on the stack (at least on the best CL implementations: SBCL, CCL, etc...) -- Stelian Ionescu a.k.a. fe[nl]ix Quidquid latine dictum sit, altum videtur. http://common-lisp.net/project/iolib |