November 2013 - cffi-devel - mailman3.common-lisp.net

Returning errno as a second value
by Felix Filozov 28 Jan '14

28 Jan '14

Hi all, In Allegro CL, the only safe way to get errno after a foreign function call is to configure the foreign function definition to return it as a second value. CFFI doesn't deal with errno. There has been some previous discussion ( http://lists.common-lisp.net/pipermail/cffi-devel/2009-January/003017.html) to return errno safely, but doesn't seem like it went anywhere. So any library that tries to get errno is potentially broken in Allegro CL. I'm seeing this in practice with lisp-zmq, for example. I'd like to introduce a new option to defcfun and foreign-funcall called :errno. It would look like this: (foreign-funcall ("strlen" :errno t) :string "foo" :int), or (defcfun (strlen "strlen" :errno t) :int (s :string)). Calling (strlen) would return two values, the return value of the foreign call, and errno. In some Lisps, the only way to get errno is to make an additional foreign call. Then perhaps that call could be made by CFFI and returns as the second value. I've created a pull request (https://github.com/cffi/cffi/pull/28) with a very rudimentary implementation for Allegro CL. Since CFFI delegates the handling of errno to the implementation, perhaps we could preserve the status quo and not get bugged down in grandiose plans of portability. Thoughts and suggestions are welcome. Thanks, Felix

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[cffi-devel] How to define a pointer to a 2d array
by Joeish W 08 Dec '13

08 Dec '13

I have a function that accepts a void* as a parameter Im trying to convert this to use as the void* float trainingData[4][2] = { {501, 10}, {255, 10}, {501, 255}, {10, 501} }; this is how i do a void* 1d array float labels[4] = {1.0, -1.0, -1.0, -1.0}; (labels (foreign-alloc :float :initial-contents '(1.0 -1.0 -1.0 -1.0))) so how do i do the 2d array

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[cffi-devel] C to Lisp
by Greg Bennett 27 Nov '13

27 Nov '13

Good morning, I (think I) might be close to getting a result in having a C function return its output to Lisp. I shall be very grateful for comments and corrections to what I have done, and thank readers for their patience. Here is the C-function from which I wish to get the result Hello Lisp from C on the lisp side: /* Hello.c program */ #include<stdio.h> void Hello(void) { printf("Hello Lisp from C\n"); return 0 ; } At the end of the process, I hope to be able to do this on the Lisp side: (defcfun ("Hello" HiFromC) (:void)) and then (HiFromC) -> Hello Lisp from C Both C and Lisp sessions are below in case details are relevant. Somewhere I have missed a critical element. Thanks to a message from Luis Oliveira pointing me to the necessity of using a shared library as the intermediary between C and Lisp. There seem to be as many recipes for creating such libraries as there are posters of the topic, and as many variations on the code too. I have put together the C side following very much this page: www.cprogramming.com/tutorial/shared-libraries-linux-gcc.html In file /home/gwbennett/Hello.h #ifndef Hello_h__ #define Hello_h__ extern void Hello(void); #endif // Hello_h__ In file /home/gwbennett/Hello.c /* Hello program */ #include<stdio.h> void Hello(void) { printf("Hello Lisp from C\n"); return 0 ; } In file main.c /* This is main.c to go with Hello.c,h */ #include <stdio.h> #include "Hello.h" int main (void) { Hello(); return 0; } Then gcc -c -Wall -Werror -fpic Hello.c -> OK gcc -shared -o libfHello.so Hello.o -> OK gcc -L/home/gwbennett -Wall -o test main.c -lHello -> OK Step 4 of the above page is about making the library visible. I have tried all 3 routes with the same results; at the moment I have taken the path of installing libHello.so in /usr/lib (and in /usr/loca/lib too)as described in the Section Using ldconfig to modify ld.so gcc -Wall -o test main.c -lfoo -> OK ldd test | grep foo -> /usr/locl/lib/libHello.so (0x00007f946c0c4000) ./test -> Hello Lisp from C so things seem to work down the C-side On the Lisp side I (hope I) am following the cffi manual page 10. I assume that cffi looks for shared libraries in the same sort of 'system' places as C, but just in case, see page 106 on *foreign-library-directories*. Start ccl version 1.9-r15972M (LinuxX8664) (require :cffi) -> OK (defpackage :cffi-user (:use :common-lisp :cffi)) -> OK (in-package :cffi-user) -> OK ;P106 (pushnew #P/"usr/lib" *foreign-library-directories* :test #'equal) -> OK (pushnew #P"/usr/local/lib" *foreign-library-directories* :test #'equal) -> OK (load-foreign-library '(:default "LibHello")) -> OK ;; I think I should be able to define the C -> Lisp name function (defcfun ("Hello" HiFromC) (:void)) -> HIFROMC ;; and execute it to get the message (HiFromC) -> NIL ;; .. so evidently I have not completely understood what is necessary to achieve the desired result. Again, thanks for any and all assistance. Cheers /Greg Bennett

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[cffi-devel] cffi and c++
by Greg Bennett 24 Nov '13

24 Nov '13

As I start to learn about cffi, I see that the manual is copyright 2005 and mentions that C++ support is incomplete but being worked on. I should appreciate knowing what the current status of cffi is with respect to c++. Thx /Greg Bennett

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Re: [cffi-devel] Access to code
by Luís Oliveira 24 Nov '13

24 Nov '13

On Sat, Nov 23, 2013 at 12:56 AM, Greg Bennett <gwbennett(a)sentex.ca> wrote: > At least I have a way forward: make up a simple c function - dear old > Hello World will do. Compile a shared library containing it. Load that > as you suggest. Use defcfun to give it a lisp name. Try calling that > name. > > As an aside: > I had hoped that the tutorial would hold that sort of simple example. I think it never occurred to us that the instructions on how to compile a shared library should be on the tutorial. I suppose it assumes you already have a shared library to start with. Where do you think that should be made more clear? > I cut+pasted segments of it into ccl version 1.9-r15972M (LinuxX8664) > only to have it break in two places: > section 4.7 when trying to call (set-curl-option-nosignal *easy-handle* > 1) WITHOUT having executed the 2 progn's in that section (mistakenly > assuming that the function was built automatically) only to be told > that there was no such function. Going back and executing the progn's > seemed to fix that. > > section 4.8 when executing (set-curl-option-url *easy-handle* > "http://www.cliki.net/CFFI") only to be told > The value "http://www.cliki.net/CFFI" is not of the expected type > CCL:MACPTR > > at which point I abandoned the tutorial. Notice the preceding paragraph. That code is merely illustrative. See the "Returning to the current set-curl-option-url interface, here is what we must do..." bits that follow. HTH, -- Luís Oliveira http://kerno.org/~luis/

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[cffi-devel] What do i do with a c "bool" return type
by Joeish W 23 Nov '13

23 Nov '13

Here is the function im wrapping a c wrapper for a c++ opencv function and below it my wrapper bool cv_VideoCapture_isOpened0(VideoCapture* self) { return self->isOpened(); } (cffi:defcfun ("cv_VideoCapture_isOpened0" %vid-cap-cam-is-open) :pointer (self (:pointer video-capture))) not sure how to call the bool return type, the below defun didnt work using pointer for return type or int on defcfun and casting from boolean inside the defun below with (convert-from-foreign ,var :boolean). when i used a pointer return type, as swig wraps it i mem-refed or mem-arefed the defcun as :int in my defun below (defun video-cap-cam-is-open (self) (convert-from-foreign (%video-cap-cam-is-open self) :boolean)) in c++ the cout output of the functions im wrapping are 1 for the first one and 0 for the one after cap.release(); is called cout << "a =" << cap.isOpened(); = 1 cap.release(); cout << "b = " << cap.isOpened(); = 0 function documentation for function im wrapping is here http://docs.opencv.org/modules/highgui/doc/reading_and_writing_images_and_v…

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[cffi-devel] Access to code
by Greg Bennett 22 Nov '13

22 Nov '13

Running under linux mint 14 64 bit; using ccl as the lisp. I have been looking at the examples provided with the cffi material, as well as at the manual, to see how the wrapping of c functions seems to work. These are very helpful but depend on system calls and "eveything" knows where they are. Suppose I have a set of c functions, and their .o files too, which I would like to wrap using defcfun and relatives. What precautions must I take in making known to ccl the locations(s) of these foreign files ? Is it a bit like asdf with a *central-registry* to hold such locations, or have I missed some obvious pointer to the answer ? Thanks for any and all assistance. Cheers /Greg Bennett

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[cffi-devel] Possible foreign-free bug
by Joeish W 12 Nov '13

12 Nov '13

(defun get-cols-example () (let* ((matrix (create-mat 5 7 +8uc1+)) (submat (foreign-alloc `(:struct cv-mat) :initial-contents '()))) (get-cols matrix submat 0 3) (foreign-free submat))) when i run the above code with the (get-cols matrix submat 0 3) line commented or without foreign-free it runs fine but as it is above i get below error Error in `/usr/bin/sbcl': free(): invalid next size (fast): 0x00007fffd4000c60 *** in inferior lisp followed by many lines of code las below. All the fuinctions in the defun above are neccessary to reproduce issue: ======= Backtrace: ========= /lib/x86_64-linux-gnu/libc.so.6(+0x80996)[0x7ffff7154996] [0x100681f7b8] ======= Memory map: ======== 00400000-00435000 r-xp 00000000 08:03 135423 /usr/bin/sbcl 00635000-00636000 r-xp 00035000 08:03 135423 /usr/bin/sbcl 00636000-00648000 rwxp 00036000 08:03 135423 /usr/bin/sbcl I dont have any foreign-free functions in my wrappers and the functions involved GET-COLS and CREATE-MAT are wrappers for OpenCV's cvGetCols and cvCreateMat...the wrappers are below for debugging purpose ;; CvMat* cvGetCols(const CvArr* arr, CvMat* submat, int start_col, int end_col) (defcfun ("cvGetCols" get-cols) (:pointer (:struct cv-mat)) "Returns array column span." (arr cv-arr) (submat (:pointer (:struct cv-mat))) (start-col :int) (end-col :int)) ;; CvMat* cvCreateMat(int rows, int cols, int type) (defcfun ("cvCreateMat" create-mat) (:pointer (:struct cv-mat)) (rows :int) (cols :int) (type :int)) any way i can help debug this i will and any guidance on this issue is much appreciated =)

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[cffi-devel] possible foreign-free bug
by Joeish W 12 Nov '13

12 Nov '13

(defun get-cols-example () (let* ((matrix (create-mat 5 7 +8uc1+)) (submat (foreign-alloc `(:struct cv-mat) :initial-contents '()))) (get-cols matrix submat 0 3) (foreign-free submat))) when i run the above code with the (get-cols matrix submat 0 3) line commented or without foreign-free it runs fine but as it is above i get below error Error in `/usr/bin/sbcl': free(): invalid next size (fast): 0x00007fffd4000c60 *** in inferior lisp followed by many lines of code las below. All the fuinctions in the defun above are neccessary to reproduce issue: ======= Backtrace: ========= /lib/x86_64-linux-gnu/libc.so.6(+0x80996)[0x7ffff7154996] [0x100681f7b8] ======= Memory map: ======== 00400000-00435000 r-xp 00000000 08:03 135423 /usr/bin/sbcl 00635000-00636000 r-xp 00035000 08:03 135423 /usr/bin/sbcl 00636000-00648000 rwxp 00036000 08:03 135423 /usr/bin/sbcl I dont have any foreign-free functions in my wrappers and the functions involved GET-COLS and CREATE-MAT are wrappers for OpenCV's cvGetCols and cvCreateMat...the wrappers are below for debugging purpose ;; CvMat* cvGetCols(const CvArr* arr, CvMat* submat, int start_col, int end_col) (defcfun ("cvGetCols" get-cols) (:pointer (:struct cv-mat)) "Returns array column span." (arr cv-arr) (submat (:pointer (:struct cv-mat))) (start-col :int) (end-col :int)) ;; CvMat* cvCreateMat(int rows, int cols, int type) (defcfun ("cvCreateMat" create-mat) (:pointer (:struct cv-mat)) (rows :int) (cols :int) (type :int)) any way i can help debug this i will and any guidance on this issue is much appreciated =)

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[cffi-devel] Possible foreign-free bug
by Joeish W 11 Nov '13

11 Nov '13

(defun get-cols-example () (let* ((matrix (create-mat 5 7 +8uc1+)) (submat (foreign-alloc `(:struct cv-mat) :initial-contents '()))) (get-cols matrix submat 0 3) (foreign-free submat))) when i run the above code with the (get-cols matrix submat 0 3) line commented or without foreign-free it runs fine but as it is above i get below error Error in `/usr/bin/sbcl': free(): invalid next size (fast): 0x00007fffd4000c60 *** in inferior lisp followed by many lines of code las below. All the fuinctions in the defun above are neccessary to reproduce issue: ======= Backtrace: ========= /lib/x86_64-linux-gnu/libc.so.6(+0x80996)[0x7ffff7154996] [0x100681f7b8] ======= Memory map: ======== 00400000-00435000 r-xp 00000000 08:03 135423 /usr/bin/sbcl 00635000-00636000 r-xp 00035000 08:03 135423 /usr/bin/sbcl 00636000-00648000 rwxp 00036000 08:03 135423 /usr/bin/sbcl I dont have any foreign-free functions in my wrappers and the functions involved GET-COLS and CREATE-MAT are wrappers for OpenCV's cvGetCols and cvCreateMat...the wrappers are below for debugging purpose ;; CvMat* cvGetCols(const CvArr* arr, CvMat* submat, int start_col, int end_col) (defcfun ("cvGetCols" get-cols) (:pointer (:struct cv-mat)) "Returns array column span." (arr cv-arr) (submat (:pointer (:struct cv-mat))) (start-col :int) (end-col :int)) ;; CvMat* cvCreateMat(int rows, int cols, int type) (defcfun ("cvCreateMat" create-mat) (:pointer (:struct cv-mat)) (rows :int) (cols :int) (type :int)) any way i can help debug this i will and any guidance on this issue is much appreciated =)

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[cffi-devel] Help with defcallback....shorter version
by Joeish W 11 Nov '13

11 Nov '13

What am i doing wrong in my conversion of this c code to lisp I think the issue is with my callback function but not 100% when i run the c code and print with these 2 lines(from c callback): cout << "a = " << "(" << "" << "," << _a << ")" << endl ; cout << "b = " << "(" << "" << "," << _b << ")" << endl; i get 53 elements printed not icluding the other printf output and in the lisp code i converterd when i print with this line(from lisp defcallback): (format t "~%x~a~%b~a" _a _b) in the defcallback i get 114 elements Hoping someone can look at my code and tell me if my coding is off the -> is a macro for with-foreign-slots (and if not a pointer just a getf for a plist) ;;;;;;;;C CODE;;;;;;;;;;;;;;;;;;; static int cmp_func( const void* _a, const void* _b, void* userdata ) { CvPoint* a = (CvPoint*)_a; CvPoint* b = (CvPoint*)_b; cout << "a = " << "(" << "" << "," << _a << ")" << endl ; cout << "b = " << "(" << "" << "," << _b << ")" << endl; int y_diff = a->y - b->y; int x_diff = a->x - b->x; return y_diff ? y_diff : x_diff; } ;;;;;;;;;;;;;;;;;;;;;;;;;LISP CODE;;;;;;;;;;;;;;;;;;;; (defcallback cmp-func :void ((_a :pointer) (_b :pointer) (user-data :pointer) (a :int) (b :int) (y-diff :int) (x-diff :int)) (format t "~%x~a~%b~a" _a _b) (setf a (mem-aref _a '(:struct cv-point))) (setf b (mem-aref _b '(:struct cv-point))) ;(format t "~%a~a~%b~a" a b) (setf y-diff (- (-> cv-point a y) (-> cv-point b y))) (setf x-diff (- (-> cv-point a x) (-> cv-point b x))) (if y-diff y-diff x-diff)) using callback with (callback cmp-func) in the OpenCV function cvSeqSort ....here is documentation for cvSeqSort http://docs.opencv.org/modules/core/doc/dynamic_structures.html?highlight=c… the code the wrapper is used in is posted in the "Help with defcallback" post below this one

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[cffi-devel] Help with defcallback
by Joeish W 11 Nov '13

11 Nov '13

I think the issue is with my callback function but not 100% when i run the c code and print with these 2 lines(from c callback): cout << "a = " << "(" << "" << "," << _a << ")" << endl ; cout << "b = " << "(" << "" << "," << _b << ")" << endl; i get 53 elements printed not icluding the other printf output and in the lisp code i converterd when i print with this line(from lisp defcallback): (format t "~%x~a~%b~a" _a _b) in the defcallback i get 114 elements Hoping someone can look at my code and tell me if my coding is off ....the functions you wont recognize are opencv functions with correctly lispified names i/e cvSeqSort = seq-sort ... If requested will post the wrappers .... the -> is a macro for with-foreign-slots (and if not a pointer just a getf for a plist) ;;;;;;;;C CODE;;;;;;;;;;;;;;;;;;; #include <cv.h> #include <highgui.h> using namespace std; static int cmp_func( const void* _a, const void* _b, void* userdata ) { //cout << "test"; //cout <<_a << _b; CvPoint* a = (CvPoint*)_a; CvPoint* b = (CvPoint*)_b; cout << "a = " << "(" << "" << "," << _a << ")" << endl ; cout << "b = " << "(" << "" << "," << _b << ")" << endl; int y_diff = a->y - b->y; int x_diff = a->x - b->x; return y_diff ? y_diff : x_diff; } int main() { CvMemStorage* storage = cvCreateMemStorage(0); CvSeq* seq = cvCreateSeq( CV_32SC2, sizeof(CvSeq), sizeof(CvPoint), storage ); int i; printf("\n=== Test sequence sorting ==="); for( i= 0; i < 10; i++ ) { CvPoint pt; pt.x = rand() % 1000; // 1000 以内的随机数 pt.y = rand() % 1000; cvSeqPush( seq, &pt ); } printf("\nOriginal point set:\n"); for( i = 0; i < seq->total; i++ ) { CvPoint* pt = (CvPoint*)cvGetSeqElem( seq, i ); printf( "(%d,%d)\n", pt->x, pt->y ); } cvSeqSort( seq, cmp_func, 0 /* userdata is not used here */ ); /* print out the sorted sequence */ printf("\nAfter sorting:\n"); for( i = 0; i < seq->total; i++ ) { CvPoint* pt = (CvPoint*)cvGetSeqElem( seq, i ); printf( "(%d,%d)\n", pt->x, pt->y ); } cvClearSeq( seq ); // Sequence clearing should be done before storage clearing cvReleaseMemStorage( &storage ); } ;;;;;;;;;;;;;;;;;;;;;;;;;LISP CODE;;;;;;;;;;;;;;;;;;;; (defcallback cmp-func :void ((_a :pointer) (_b :pointer) (user-data :pointer) (a :int) (b :int) (y-diff :int) (x-diff :int)) (format t "~%x~a~%b~a" _a _b) (setf a (mem-aref _a '(:struct cv-point))) (setf b (mem-aref _b '(:struct cv-point))) ;(format t "~%a~a~%b~a" a b) (setf y-diff (- (-> cv-point a y) (-> cv-point b y))) (setf x-diff (- (-> cv-point a x) (-> cv-point b x))) (if y-diff y-diff x-diff)) (defun seq-sort-example () (let* ((storage (create-mem-storage 0)) (seq (create-seq +32sc2+ (size-of cv-seq) (size-of cv-point) storage))) (format t "~%=== Test sequence sorting ===") (with-foreign-object (pt '(:struct cv-point)) (dotimes (i 10) (setf (foreign-slot-value pt '(:struct cv-point) 'x) (random 1000) (foreign-slot-value pt '(:struct cv-point) 'y) (random 1000)) (seq-push seq pt))) (with-foreign-object (pt '(:pointer (:struct cv-point))) (format t "~%Original point set:~%") (dotimes (i (-> cv-seq seq total)) (setf pt (get-seq-elem seq i)) (format t "(~a, ~a)~%" (-> cv-point pt x) (-> cv-point pt y) ))) (seq-sort seq (callback cmp-func) (null-pointer)) (with-foreign-object (pt '(:pointer (:struct cv-point))) (format t "~%After sorting:~%") (dotimes (i (-> cv-seq seq total)) (setf pt (get-seq-elem seq i)) (format t "(~a, ~a)~%" (-> cv-point pt x) (-> cv-point pt y) ))) (clear-seq seq) (release-mem-storage storage)))

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[cffi-devel] Fw: Struct member changes when its assigned back to variable it was dereferenced from...do same in lisp fails
by Joeish W 03 Nov '13

03 Nov '13

On Saturday, November 2, 2013 10:44 PM, Joeish W <joeish80829(a)yahoo.com> wrote: here is the c code with explanation didn't add all code to keep it short but i know it is still long...if this seems daunting because all the code I added....pls know 1. I worked on this a long time and added the minimal code i could think to explain the issue 2. if it does seem daunting...if you would be so kind as to look through this and tell me how i could edit my ? to make it easier to answer...with that being said... though this is a very simple post .... Im hoping at the end of the explanation you might be able to help me re-wrap my CV-SEQ struct so i get the same resultt as i do in c > > >CvSeq* contours; //hold the pointer to a contour in the memory block > > > >// adds data to CvSeq* contours with &contours call >cvFindContours(imgGrayScale, storage, &contours, sizeof(CvContour), CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0)); > > >// This is how its supposed to work ....no matter how many times you dereference contours to get the h_next struct member >// the value of contours->h_next is always the same > > >cout << "c1 = " << endl << " " << contours->h_next << endl << endl; //output same as next line - see output below >cout << "c2 = " << endl << " " << contours->h_next << endl << endl; //output same as above line see output below > > >// If you assign contours->h_next to a new variable "c" > >CvSeq* c = contours->h_next; > > >// then cout contours->h_next the output of the below 2 cout's is still the same as the output of the above 2 - see output below > >cout << "c3 = " << endl << " " << contours->h_next << endl << endl; >cout << "c4 = " << endl << " " << contours->h_next << endl << endl; > > >// but if you assign contours->h_next back to contours the output of the next 2 couts is different than above 4 > >// see output below > > contours = contours->h_next; >cout << "c5 = " << endl << " " << contours->h_next << endl << endl; >cout << "c6 = " << endl << " " << contours->h_next << endl << endl; > > > > >here is the cout output > > >c1 = > 0x182f730 > > >c2 = > 0x182f730 > >c3 = > 0x182f730 > >c4 = > 0x182f730 > >c5 = > 0x182f560 > >c6 = > 0x182f560 > > > > >The struct CvSeq is defined as this > >#define CV_TREE_NODE_FIELDS(node_type) \ > int flags; /* Miscellaneous flags. */ \ > int header_size; /* Size of sequence header. */ \ > struct node_type* h_prev; /* Previous sequence. */ \ > struct node_type* h_next; /* Next sequence. */ \ > struct node_type* v_prev; /* 2nd previous sequence. */ \ > struct node_type* v_next /* 2nd next sequence. */ > >/* > Read/Write sequence. > Elements can be dynamically inserted to or deleted from the sequence. >*/ >#define CV_SEQUENCE_FIELDS() \ > CV_TREE_NODE_FIELDS(CvSeq); \ > int total; /* Total number of elements. */ \ > int elem_size; /* Size of sequence element in bytes. */ \ > schar* block_max; /* Maximal bound of the last block. */ \ > schar* ptr; /* Current write pointer. */ \ > int delta_elems; /* Grow seq this many at a time. */ \ > CvMemStorage* storage; /* Where the seq is stored. */ \ > CvSeqBlock* free_blocks; /* Free blocks list. */ \ > CvSeqBlock* first; /* Pointer to the first sequence block. */ > >typedef struct CvSeq >{ > CV_SEQUENCE_FIELDS() >} >CvSeq; > > > >Im not getting the same thing as in lisp with my struct like this - SWIG wrapped > > >(cffi:defcstruct cv-seq > (flags :int) > (header-size :int) > (h-prev :pointer) > (h-next :pointer) > (v-prev :pointer) > (v-next :pointer) > (total :int) > (elem-size :int) > (block-max :pointer) > (ptr :pointer) > (delta-elems :int) > (storage :pointer) > (free-blocks :pointer) > (first :pointer)) > > > > >with the below code my output is the same for both princ...not newline of course =) > > > >(with-foreign-object (contours '(:pointer (:struct cv-seq))) > (find-contours img-grayscale storage contours > (size-of cv-contour) +retr-list+ > +chain-approx-simple+ (point 0 0)) > > (with-foreign-slots ((h-next) contours (:struct cv-seq)) > (setf contours h-next) > (princ contours) > (princ #\newline) > (setf contours h-next) > (princ contours))) > > >any help on fixing my struct, my coding or editing this post =) is much appreciated > > >Cheers! > > >

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RE: [cffi-devel] There doesn't seem to be anything in CFFI doc. about wrapping macros
by Joeish W 03 Nov '13

03 Nov '13

ok i do appreciate you help so far but 1 more thing....i get everything else you said what do i cast the return value to for CV_GET_SEQ_ELEM because the documentation for it says...."The macro checks first whether the desired element belongs to the first block of the sequence and returns it if it does; otherwise the macro calls the main function GetSeqElem" tthe documentation for cvGetSeqElem says "Returns a pointer to a sequence element according to its index." so the macro seems to have ability to return 2 separate values but the function cvGetseqElem does not....cvGetSeqElems return is usually cast to other types when its used though....I was hoping you could help me figure out how to cast its return and how to get by the parameters not being declared here i/e to int or double etc #define CV_GET_SEQ_ELEM( elem_type, seq, index ) CV_SEQ_ELEM( (seq), elem_type, (index) ) I know what these variables are i/e elem_type is an int and sq is a CvSeq*, index is an int....but i have alot glue code to write for macros like this....so if i didnt know what the variables should be declared as ....what do i do.....this will help me master this part of writing my library(gloe code for macros) if you could answer this for me On Saturday, November 2, 2013 1:14 PM, Frank Gönninger <frank.goenninger(a)consequor.de> wrote: A C macro is merely a text replacement, not a function >definition/declaration. So you can not "call" it - neither from C nor from >Lisp. > >In every place in C code where CV_SEQ_ELEM() appears the C preprocessor >replaces this *text* with what the macro generates. > >Not knowing what this macro really does it will replace > >CV_SEQ_ELEM(myseq,int,1) > >with > >( assert(sizeof((mytype)->first[0]) == sizeof(CvSeqBlock) && > (mytype)->elem_size == sizeof(int)), (int*)((mytype)->first && >(unsigned)1 < (unsigned)((mytype)->first->count) ? (mytype)->first->data + >(1) * sizeof(int) : cvGetSeqElem( (CvSeq*)(mytype), (1) ))) > >You see, a simple text replacement. > >So - all you need to do is to write a C layer that has a function around >this. If you want to do this in Lisp, then you need to manually translate >this into Lisp. You need to have a solid understanding of C and a solid >understanding of Lisp to do that. > >Cheers > Frank > >-- > C o n s e q u o r C o n s u l t i n g A G > Frank Gönninger > > Mobil: +49 175 43 21 058 > E-Mail: frank.goenninger(a)consequor.de > Telefon: +49 711 781181 10 > Fax: +49 711 781181 11 > > Consequor Consulting AG > Liebknechtstr. 33 > D-70565 Stuttgart, Germany > > Vorstand: Frank Gönninger > Aufsichtsratsvorsitzender: Dipl.-Kfm. Matthias Filbinger > Sitz der Gesellschaft: 70565 Stuttgart, Deutschland > Registergericht Amtsgericht Stuttgart HRB 727446 > > > > > > > > >Am 02.11.13 19:54 schrieb "Joeish W" unter <joeish80829(a)yahoo.com>: > >>well I have to do a glue layer for it any way because the macro gets an >>unidentified alien function error when I try to call it from a defcfun >>in lisp...I write alot of glue code for unidentified alien function >>errors but those are for functions not macros. could you help get me >> started writing a glue layer for this macro i posted so i can call it in >>a defcfun for c....i have no idea how to type cast the parameters or how >>to do a return on them...btw .sorry if i sent a reply to your mailbox >>Frank =) >> >> >> >> >> On Saturday, November 2, 2013 9:23 AM, Frank Gönninger >><frank.goenninger(a)consequor.de> wrote: >> >> >> This is a simple code generation C macro, so this is simple to be >>transcripted into Common Lisp. There are several alternatives to do this. >> >>Either you write the code explicitly in every use occasion or you write a >>Common Lisp macro that does the same. >> >>(defmacro cv-seq-elem( seq elem_type index ) >> `( >> Š >> >>But why do you what to do this in >> Lisp? I would rather write some glue >>layer in C and have much simpler calls from Lisp to C. >> >>Good luck. >> >>Frank >> >> >>Am 02.11.13 16:43 schrieb "Joeish W" unter <joeish80829(a)yahoo.com>: >> >>> >>>I'm trying to wrap the GET_SEQ_ELEM macro below can some one give me >>>clues or example how i would go about this easily >>> >>>with a cffi function like defcfun...If there is no clear way i definately >>>propose an addendum to cffi for wrapping macros >>> >>> >>>#define CV_SEQ_ELEM( seq, elem_type, index ) >> \ >>> >>>/* assert gives some guarantee that <seq> parameter is valid */ \ >>> >>>( assert(sizeof((seq)->first[0]) == sizeof(CvSeqBlock) && \ >>> >>> (seq)->elem_size == sizeof(elem_type)), \ >>> >>> (elem_type*)((seq)->first && (unsigned)index >>> < \ >>> >>> (unsigned)((seq)->first->count) ? \ >>> >>> (seq)->first->data + (index) * >> sizeof(elem_type) : \ >>> >>> cvGetSeqElem( (CvSeq*)(seq), (index) ))) >>> >>>#define CV_GET_SEQ_ELEM( elem_type, seq, index ) CV_SEQ_ELEM( (seq), >>>elem_type, (index) ) >> >> >> >> >> >> >> >> >> >> >> >> > > >

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Re: [cffi-devel] There doesn't seem to be anything in CFFI doc. about wrapping macros
by Joeish W 02 Nov '13

02 Nov '13

well I have to do a glue layer for it any way because the macro gets an unidentified alien function error when I try to call it from a defcfun in lisp...I write alot of glue code for unidentified alien function errors but those are for functions not macros. could you help get me started writing a glue layer for this macro i posted so i can call it in a defcfun for c....i have no idea how to type cast the parameters or how to do a return on them...btw .sorry if i sent a reply to your mailbox Frank =) On Saturday, November 2, 2013 9:23 AM, Frank Gönninger <frank.goenninger(a)consequor.de> wrote: This is a simple code generation C macro, so this is simple to be >transcripted into Common Lisp. There are several alternatives to do this. > >Either you write the code explicitly in every use occasion or you write a >Common Lisp macro that does the same. > >(defmacro cv-seq-elem( seq elem_type index ) > `( Š > >But why do you what to do this in Lisp? I would rather write some glue >layer in C and have much simpler calls from Lisp to C. > >Good luck. > >Frank > > > >Am 02.11.13 16:43 schrieb "Joeish W" unter <joeish80829(a)yahoo.com>: > >> >>I'm trying to wrap the GET_SEQ_ELEM macro below can some one give me >>clues or example how i would go about this easily >> >>with a cffi function like defcfun...If there is no clear way i definately >>propose an addendum to cffi for wrapping macros >> >> >>#define CV_SEQ_ELEM( seq, elem_type, index ) \ >> >>/* assert gives some guarantee that <seq> parameter is valid */ \ >> >>( assert(sizeof((seq)->first[0]) == sizeof(CvSeqBlock) && \ >> >> (seq)->elem_size == sizeof(elem_type)), \ >> >> (elem_type*)((seq)->first && (unsigned)index >> < \ >> >> (unsigned)((seq)->first->count) ? \ >> >> (seq)->first->data + (index) * sizeof(elem_type) : \ >> >> cvGetSeqElem( (CvSeq*)(seq), (index) ))) >> >>#define CV_GET_SEQ_ELEM( elem_type, seq, index ) CV_SEQ_ELEM( (seq), >>elem_type, (index) ) > > >

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[cffi-devel] There doesn't seem to be anything in CFFI doc. about wrapping macros
by Joeish W 02 Nov '13

02 Nov '13

I'm trying to wrap the GET_SEQ_ELEM macro below can some one give me clues or example how i would go about this easily with a cffi function like defcfun...If there is no clear way i definately propose an addendum to cffi for wrapping macros #define CV_SEQ_ELEM( seq, elem_type, index ) \ /* assert gives some guarantee that <seq> parameter is valid */ \ ( assert(sizeof((seq)->first[0]) == sizeof(CvSeqBlock) && \ (seq)->elem_size == sizeof(elem_type)), \ (elem_type*)((seq)->first && (unsigned)index < \ (unsigned)((seq)->first->count) ? \ (seq)->first->data + (index) * sizeof(elem_type) : \ cvGetSeqElem( (CvSeq*)(seq), (index) ))) #define CV_GET_SEQ_ELEM( elem_type, seq, index ) CV_SEQ_ELEM( (seq), elem_type, (index) )

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[cffi-devel] There doesn't seem to be anything in CFFI doc. about wrapping macros
by Joeish W 02 Nov '13

02 Nov '13

I'm trying to wrap the GET_SEQ_ELEM macro below can some one give me clues or example how i would go about this easily with a cffi function like defcfun...If there is no clear way i definately propose an addendum to cffi for wrapping macros #define CV_SEQ_ELEM( seq, elem_type, index ) \ /* assert gives some guarantee that <seq> parameter is valid */ \ ( assert(sizeof((seq)->first[0]) == sizeof(CvSeqBlock) && \ (seq)->elem_size == sizeof(elem_type)), \ (elem_type*)((seq)->first && (unsigned)index < \ (unsigned)((seq)->first->count) ? \ (seq)->first->data + (index) * sizeof(elem_type) : \ cvGetSeqElem( (CvSeq*)(seq), (index) ))) #define CV_GET_SEQ_ELEM( elem_type, seq, index ) CV_SEQ_ELEM( (seq), elem_type, (index) )

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[cffi-devel] Help with recursive struct member
by Joeish W 01 Nov '13

01 Nov '13

here is the way CvMemStorage is defined typedef struct CvMemStorage { int signature; CvMemBlock* bottom; /* First allocated block. */ CvMemBlock* top; /* Current memory block - top of the stack. */ struct CvMemStorage* parent; /* We get new blocks from parent as needed. */ int block_size; /* Block size. */ int free_space; /* Remaining free space in current block. */ } CvMemStorage; bu i get unknown CFFI type: (:STRUCT CV-MEM-STORAGE). [Condition of type SIMPLE-ERROR] when i wrap like this....i know lisp is known for recursion how do i bypass this (defcstruct cv-mem-storage (signature :int) (bottom (:pointer (:struct cv-mem-block))) (top (:pointer (:struct cv-mem-block))) (parent (:pointer (:struct cv-mem-storage))) (block-size :int) (free-space :int))

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[cffi-devel] help writing macro for with-foreign-slots aka help with the ULTIMATE derefrencing macro
by Joeish W 01 Nov '13

01 Nov '13

I'm trying to write an all purpose dereferencing macro...ive done pretty good so far I have (defmacro -> (var1 var2 var3 &optional var4 var5) ;; if var4 and var5 arent supplied give value of struct member (if (not (and var4 var5)) `(cffi:with-foreign-slots ((,var3) ,var2 (:struct ,var1)) (list ,var3)) ;; if var4 and var5 are supplied give value of nested struct member (if (and var4 var5) `(cffi:with-foreign-slots ((,var3) ,var2 (:struct ,var1)) (cffi:with-foreign-slots ((,var5) ,var3 (:struct ,var4)) ,var5) )))) the roi struct member of ipl-image is defined as this (roi (:pointer (:struct ipl-roi))) ;this gets the roi slot value of ipl-image correctly CL-OPENCV> (-> ipl-image a roi ) (#.(SB-SYS:INT-SAP #X7FFFDC000E80)) ;this gets the nested struct member "width" of ipl-roi which is just a an :int correctly CL-OPENCV> (-> ipl-image a roi ipl-roi width) 100 both work correctly but i could use help getting rid of some of the typing to access these members in this (-> ipl-image a roi ipl-roi width) i have to type "ipl-image"(the name of the struct) "a"( the name of the variable i'm dereferencing) "roi" (the name of the ipl-image struct member) "ipl-roi" (the foreign-type of roi) and "width" (the ipl-roi struct member) . if there was a way i can get the foreign type of the roi struct member like i can call foreign-slot-names to get all the slot names of a struct i could not have to use the ipl-roi here (-> ipl-image a roi ipl-roi width) but i looked in the manual and nothing....I couldnt think of any other way to shorten this (-> ipl-image a roi ipl-roi width) and make it a little closer to c so if someone could give me advice, or better yet their awesome dereferencing macro=), i named this post so everyone....including me=) would have access to this great information

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