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

[Sylvain Ageneau]

Great!

I'll try that and report back. Many thanks.

On Nov 22, 2012, at 11:16 AM, Juan Jose Garcia-Ripoll <juanjose.garciaripoll at gmail.com> wrote:

> 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
> <build.lisp><cffi-test.lisp><0001-Allow-the-ECL-backend-to-support-different-combinati.patch>

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