cffi-devel September 2010

cffi-devel@common-lisp.net

6 participants
3 discussions

[cffi-devel] offer of code contribution - with-array-as-foreign-pointer
by JTK 13 Sep '10

13 Sep '10

Hello, I'm using cffi, and I need to perform the common task of passing Lisp arrays to foreign code. This task comes up a lot in scientific code, matrix math, image processing, etc. Normally, it involves a lot of boilerplate to allocate a pointer, copy data Lisp to foreign memory, copy the data back, and deallocate the memory. Getting the copying to run fast can be tricky. Hence I wrote a package to automate it. It maintains a set of specialized copying functions to copy from array of Lisp type X to foreign memory of type Y. On SBCL, copying doesn't cons and is reasonably fast (~200 MB a second, there and back) I've put the package here: http://www.megaupload.com/?d=CX1XFMU6 Sorry for the megaupload, and its imposed delay, but I didn't want to spam the list with a 100K file. The package includes a MANUAL.txt and a test package. I'd be happy to have this included in a user contrib section of CFFI, if the maintainers think it would be useful. Here's an example the main macro does: (LET ((U (MAKE-ARRAY 100 :ELEMENT-TYPE 'SINGLE-FLOAT :INITIAL-ELEMENT 1.0))) ;; (WITH-ARRAY-AS-FOREIGN-POINTER (U PU :FLOAT ;; LISP-VAR POINTER-VAR CFFI-FOREIGN-TYPE :LISP-TYPE SINGLE-FLOAT ;; promise U is a single-float array :START 2 ;; begin at index 2 of of Lisp array :END 7 ;; last index used is 6 :COPY-TO-FOREIGN T ;; put contents of Lisp into foreign memory :COPY-FROM-FOREIGN T) ;; copy back from FFI space to lisp array ;; ;; at this point, PU is a foreign pointer containing data copied ;; from the array starting at element 1 and ending at 6, of type :FLOAT. (SOME-FOREIGN-FUNCTION PU)) ;; ;; at end, all foreign memory is deallocated, and U has been copied ;; back from foreign space, but the 0th element of U is untouched ;; because START was 1, not 0 ) -John

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[cffi-devel] more flexible name translation
by Greg Pfeil 06 Sep '10

06 Sep '10

Here's a patch that makes name translation between lisp and foreign names more flexible. I often find that I'm using libraries that don't use underscore_separated_names, and rather than always doing (defcfun (some-fun "someFun") ...) I end up doing local hacks so I can just define the translation rules once and only use the (symbol "string") style for exceptions. This patch makes those local hacks less hacky. It means in my wrapper, I can define methods on CFFI:LISP-NAME and CFFI:FOREIGN-NAME (as in http://github.com/sellout/CL-LLVM/blob/master/cffi.lisp) to create custom translations (specialized on the package, so other wrappers can use their own translations).

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Re: [cffi-devel] uffi compatible library
by Gustavo 06 Sep '10

06 Sep '10

Those don't fail, but: UFFI-TESTS> (let ((native-string "test string")) (uffi:with-foreign-string (fs native-string) (ensure-char-character (deref-pointer fs :char)))) #\t UFFI-TESTS> (let ((native-string "test string")) (uffi:with-foreign-string (fs native-string) (deref-pointer fs :char))) 116 The latter would return #\t in uffi-compat. Em 22 de agosto de 2010 18:25, Luís Oliveira <luismbo(a)gmail.com> escreveu: 2010/8/10 Gustavo <gugamilare(a)gmail.com>: > > I found one inconsistency in uffi's documentation. Uffi's doc says that > > dereferencing types :char and :unsigned-char return characters where > > actually it returns integers (at least here). > > Does that mean these tests fail for you? > <http://git.b9.com/?p=uffi.git;a=blob;f=tests/objects.lisp> > > -- > Luís Oliveira > http://r42.eu/~luis/ <http://r42.eu/%7Eluis/> >

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cffi-devel September 2010