[Ecls-list] ECL & static symbol references with CFFI

[Juan Jose Garcia-Ripoll]

I am attaching a patch for CFFI that allows ECL to build code that does not
use dlopen() but rather uses the function symbols as they are know to the C
compiler. This is best explained in the code comments, which I reproduce
below, and in the example.

The patched CFFI is available at my github account
https://github.com/juanjosegarciaripoll/cffi

This is how the example is used

bash-3.2$ ecl -norc
ECL (Embeddable Common-Lisp) 12.7.1
(git:e95fa190ccab10a5dcca791658d7d3ff24a77240)
Copyright (C) 1984 Taiichi Yuasa and Masami Hagiya
Copyright (C) 1993 Giuseppe Attardi
Copyright (C) 2000 Juan J. Garcia-Ripoll
ECL is free software, and you are welcome to redistribute it
under certain conditions; see file 'Copyright' for details.
Type :h for Help.
Top level in: #<process TOP-LEVEL>.
> (load "build")
[...]
To load "cffi":
  Load 1 ASDF system:
    cffi
; Loading "cffi"

;;;
;;; Compiling cffi-test.lisp.
;;; OPTIMIZE levels: Safety=2, Space=0, Speed=3, Debug=0
;;;
;;; Compiling (CFFI:DEFCFUN ("sin" C-SINE) ...).
;;; Compiling (DEFUN FF-C-SINE ...).
;;; End of Pass 1.
;;; Emitting code for C-SINE.
;;; Emitting code for FF-C-SINE.
;;; Finished compiling cffi-test.lisp.
;;;
;;; Loading "/Users/jjgarcia/build/cffi-static/cffi-test.fas"

 sin(pi) = 1.22464679914735320720000000000000d-16
#P"/Users/jjgarcia/build/cffi-static/build.lisp"

This is the self-explanatory comment

;;;
;;; ECL allows many ways of calling a foreign function, and also many
;;; ways of finding the pointer associated to a function name. They
;;; depend on whether the FFI relies on libffi or on the C/C++ compiler,
;;; and whether they use the shared library loader to locate symbols
;;; or they are linked by the linker.
;;;
;;;  :DFFI
;;;
;;;  ECL uses libffi to call foreign functions. The only way to find out
;;;  foreign symbols is by loading shared libraries and using dlopen()
;;;  or similar.
;;;
;;;  :DLOPEN
;;;
;;;  ECL compiles FFI code as C/C++ statements. The names are resolved
;;;  at run time by the shared library loader every time the function
;;;  is called
;;;
;;;  :C/C++
;;;
;;;  ECL compiles FFI code as C/C++ statements, but the name resolution
;;;  happens at link time. In this case you have to tell the ECL
;;;  compiler which are the right ld-flags (c:*ld-flags*) to link in
;;;  the library.
;;;
(defvar *cffi-ecl-method*
  #+dffi :dffi
  #+(and dlopen (not dffi)) :dlopen
  #-(or dffi dlopen) :c/c++
  "The type of code that CFFI generates for ECL: :DFFI when using the
dynamical foreign function interface; :DLOPEN when using C code and
dynamical references to symbols; :C/C++ for C/C++ code with static
references to symbols.")


-- 
Instituto de Física Fundamental, CSIC
c/ Serrano, 113b, Madrid 28006 (Spain)
http://juanjose.garciaripoll.googlepages.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.common-lisp.net/pipermail/ecl-devel/attachments/20121122/b9c75726/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: build.lisp
Type: application/octet-stream
Size: 241 bytes
Desc: not available
URL: <https://mailman.common-lisp.net/pipermail/ecl-devel/attachments/20121122/b9c75726/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cffi-test.lisp
Type: application/octet-stream
Size: 643 bytes
Desc: not available
URL: <https://mailman.common-lisp.net/pipermail/ecl-devel/attachments/20121122/b9c75726/attachment-0001.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-Allow-the-ECL-backend-to-support-different-combinati.patch
Type: application/octet-stream
Size: 6279 bytes
Desc: not available
URL: <https://mailman.common-lisp.net/pipermail/ecl-devel/attachments/20121122/b9c75726/attachment-0002.obj>