cffi-devel May 2014

cffi-devel@common-lisp.net

5 participants
9 discussions

[Cffi-devel] FSBV question
by Cyrus Harmon 01 Jun '14

01 Jun '14

So I’ve been trying to get FSBV working on ABCL and I’ve run into a problem with returning structs. The problem is that we allocate memory on the stack for the return struct, successfully call the foreign function, writing the return value into the appropriate place, then we free the memory and return a pointer to the now defunct memory location. I’m curious as to how this is supposed to work in other implementations. It obviously does work in, at least, SBCL, so I must be doing something wrong. But looking at the ffcall-body-libffi function it looks like we setup the foreign memory for RESULT in with-foreign-objects and then if we have a translatable-foreign-type, we return RESULT, which of course gets freed by with-foreign-objects. What am I missing here? thanks, Cyrus (defun ffcall-body-libffi (function symbols return-type argument-types &optional pointerp (abi :default-abi)) "A body of foreign-funcall calling the libffi function #'call (ffi_call)." (let ((number-of-arguments (length argument-types))) `(with-foreign-objects ((argvalues :pointer ,number-of-arguments) ,@(unless (eql return-type :void) `((result ',return-type)))) (loop :for arg :in (list ,@symbols) :for count :from 0 :do (setf (mem-aref argvalues :pointer count) arg)) (call (prepare-function ,function ',return-type ',argument-types ',abi) ,(if pointerp function `(foreign-symbol-pointer ,function)) ,(if (eql return-type :void) '(null-pointer) 'result) argvalues) ,(if (eql return-type :void) '(values) (if (typep (parse-type return-type) 'translatable-foreign-type) ;; just return the pointer so that expand-from-foreign ;; can apply translate-from-foreign 'result ;; built-in types won't be translated by ;; expand-from-foreign, we have to do it here `(mem-aref result ',return-type))))))

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[Cffi-devel] Could you make a release please?
by Anton Vodonosov 29 May '14

29 May '14

Hi, could you make a release please? I am very interested in commit bb629a853a to be in Quicklisp. Quicklisp currently grabs cffi from http http://common-lisp.net/project/cffi/releases/cffi_latest.tar.gz Best regards, - Anton

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[Cffi-devel] How do I wrap a C/C++ struct with a nested union
by Joeish W 27 May '14

27 May '14

I'm trying to wrap this struct, CvDTreeSplit. Normally I just use swig to wrap them but in this case when I wrap the C++ struct, CvDTreeSplit, below, I get this error in swig: Warning 312: Nested union not currently supported (ignored). So the output ends up being the defcstruct at the bottom of the page. Not sure where to go from here. Can someone wrap this struct for me so I'll know how to wrap structs, with nested unions, containing structs and C arrays, in the future. struct CvDTreeSplit { int var_idx; int condensed_idx; int inversed; float quality; CvDTreeSplit* next; union { int subset[2]; struct { float c; int split_point; } ord; }; }; (cffi:defcstruct CvDTreeSplit (var_idx :int) (condensed_idx :int) (inversed :int) (quality :float) (next :pointer))

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[Cffi-devel] Is there anything in CFFI where I can cast an integer to a char and the result is a letter..
by Joeish W 18 May '14

18 May '14

This is the code I'm referring to : char c = (char)waitKey(); if( c == 27 ) break; if( c == 'r' ) {..... The function waitKey, above, outputs an integer as return and it's being cast to a char to make the result a letter. Can this be done in CFFI.I have a CFFI wrapper for waitKey btw, that has an :int return

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[Cffi-devel] What is wrong with this 2d array of pointers
by Joeish W 11 May '14

11 May '14

I was hoping someone could look at this and help me debug it. I'm getting: (FOREIGN-ALLOC :POINTER :INITIAL-ELEMENT (NULL-POINTER)) is not of type SB-SYS:SYSTEM-AREA-POINTER. when I run it. (foreign-array-alloc #2A(( (foreign-alloc :pointer :initial-element (null-pointer)) (foreign-alloc :pointer :initial-element (null-pointer))) ((foreign-alloc :pointer :initial-element (null-pointer)) (foreign-alloc :pointer :initial-element (null-pointer))) ((foreign-alloc :pointer :initial-element (null-pointer)) (foreign-alloc :pointer :initial-element (null-pointer))) ((foreign-alloc :pointer :initial-element (null-pointer)) (foreign-alloc :pointer :initial-element (null-pointer)))) '(:array :pointer 4 2))

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[Cffi-devel] Still can't mem-aref the output of a metaobject with provided code
by Joeish W 11 May '14

11 May '14

I do appreciate all your attention to my types GC issue so far but when Wim gave me this untested code: (defmethod translate-to-foreign ((lisp-value cv-matrix) (c-type cv-mat)) (values (c-pointer lisp-value) lisp-value)) I thought it worked but I still had my mem-aref macro defined to access the c-pointer value so I didn't get a good test? for example I'm referring to the lisp wrapper for this C function now, but it is identical to the cv-matrix one: Scalar* cv_create_Scalar(double val0, double val1, double val2, double val3) { return new Scalar(val0, val1, val2, val3); } I now have my lisp wrapper and types/finalizers for the above c function defined like this: (defcfun ("cv_create_Scalar" %scalar) scalar (val0 :double) (val1 :double) (val2 :double) (val3 :double)) (define-foreign-type scalar () ((garbage-collect :reader garbage-collect :initform nil :initarg :garbage-collect)) (:actual-type :pointer) (:simple-parser scalar)) (defclass cv-scalar () ((c-pointer :reader c-pointer :initarg :c-pointer))) (defmethod translate-to-foreign ((lisp-value cv-scalar) (c-type scalar)) (values (c-pointer lisp-value) lisp-value)) <--the new version Wim gave me untested (defmethod translate-from-foreign (c-pointer (c-type scalar)) (let ((scalar (make-instance 'cv-scalar :c-pointer c-pointer))) (when (garbage-collect c-type) (tg:finalize scalar (lambda () (del-scalar c-pointer)))) scalar)) When I run (defparameter a (%scalar 1d0 2d0 3d0 4d0)) and (mem-aref a :double) I still get: The value #<CV-SCALAR {10046BC833}> is not of type SB-SYS:SYSTEM-AREA-POINTER. but when I run (mem-aref (c-pointer a) :double) it works. What do I have to change in my types so I can mem-aref "A" normally, like this (mem-aref a :double)...Any help is much appreciated:)

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[Cffi-devel] I can use a little professional advice on my new memory management technique(read this for a fun idea)
by Joeish W 07 May '14

07 May '14

Probably about 30% of my functions need some sort of memory management. I wanted to use the TG(Trivial Garbage) finalizers for automatic MM but they were twice as slow as my original functions. So I decided to use 3 forms of MM in my library WITH-* macros, manual and finalizers. As for the finalizer part of my library, I wanted to call all my functions by the same name as well so I tried 2 things. First I wrapped everything in conditionals so I could call by the same name but that was a bit slow...so I decided to create a clone of my library named "GC" that had all the same functions but they were finalized. so If, while in my original package, where I normally use with-* macros because they are quickest, I needed one, I could append a "gc::" before the function I wanted to use and bam!, a finalized version of the function I wanted to use, with the same name(save for the gc::) and as fast as possible. The only caveat is If I use one finalizer I have to append a "gc::" to thee front of every function that takes that function as input. Once the branching for that function is over, I can do whatever I want with the rest of the functions in my code..Now I can tell you this is awesome and fun to use....but is there another better way

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[Cffi-devel] (no subject)
by Joeish W 03 May '14

03 May '14

have thes 3 defcfuns, for OpenCV functions (C++) which have been wrapped in C(C and C+++ function definitions have been included), the top 2,%brisk and surf0 can both can be used as the (self feature-detector) param in the bottom one, %feat-detect-detect. If the output of the top two and the self param of feat-detect-detect are just :pointer, But I need to have all three of their types defined similiarly to the (four type functions) on the bottom of the page so I can use finalizers. All of the finalizers and types for the three are the same, just substitute in brisk and surf for feature-detector in the four functions at the bottom of the page and you will know what each looks like. Should I just call the types for the output of brisk and surf and the input type of feat-detect-detect by the same name, and make them all use the same 4 function type/finalizer combo at the bottom of the page, or is there a better way. ;; BRISK::BRISK(int thresh=30, int octaves=3, float patternScale=1.0f) ;; BRISK* cv_create_BRISK(int thresh, int octaves, float patternScale) (defcfun ("cv_create_BRISK" %brisk) brisk (thresh :int) (octaves :int) (pattern-scale :float)) ;; SURF::SURF() ;; SURF* cv_create_SURF() (defcfun ("cv_create_SURF" surf0) surf) ;; void FeatureDetector::detect(const Mat& image, vector<KeyPoint>& keypoints, const Mat& mask=Mat() ) const ;; void cv_FeatureDetector_detect3(FeatureDetector* self, Mat* image, vector_KeyPoint* keypoints, Mat* mask) (defcfun ("cv_FeatureDetector_detect3" %feat-detector-detect) :void (self feature-detector) (image mat) (keypoints (:pointer vector-keypoint)) (mask mat)) (define-foreign-type feature-detector () ((garbage-collect :reader garbage-collect :initform nil :initarg :garbage-collect)) (:actual-type :pointer) (:simple-parser feature-detector)) (defclass cv-feature-detector () ((c-pointer :reader c-pointer :initarg :c-pointer))) (defmethod translate-to-foreign ((lisp-value cv-feature-detector) (c-type feature-detector)) (c-pointer lisp-value)) (defmethod translate-from-foreign (c-pointer (c-type feature-detector)) (let ((feature-detector (make-instance 'cv-feature-detector :c-pointer c-pointer))) (when (garbage-collect c-type) (tg:finalize feature-detector (lambda () (del-feature-detector c-pointer)))) feature-detector)) ound matches of keypoints from two images." (%draw-matches img1 keypoints1 img2 keypoints2 matches1to2 outimg match-color single-point-color matches-mask flags))

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[Cffi-devel] (no subject)
by Joeish W 03 May '14

03 May '14

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cffi-devel May 2014