RE: Re[2]: [Haskell-cafe] Basic FFI with GHC
| So, after more searching on the internet and some RTFM, I think I | found my answer, and it seems to work, but I don't know if it's the | right answer to generalize from. | | i have added your recipe to http://www.haskell.org/haskellwiki/FFI_cook_book Thank you Bulat. There's also a GHC page about the FFI here: http://haskell.org/haskellwiki/GHC/Using_the_FFI It seems reasonable to have two: one generic to Haskell and one specific to GHC. - But it would make sense to add a pointer from the generic one to the GHC one - And perhaps some of the material on the GHC page is actually generic, and should be moved? Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[4]: [Haskell-cafe] Basic FFI with GHC
Hello Simon, Thursday, September 13, 2007, 2:12:18 PM, you wrote: http://www.haskell.org/haskellwiki/FFI_cook_book There's also a GHC page about the FFI here: http://haskell.org/haskellwiki/GHC/Using_the_FFI this page, despite its name, is only about dealing with Visual C++ via DLLs. it's cookbook-style material, although rather long to be merged with former page It seems reasonable to have two: one generic to Haskell and one specific to GHC. - But it would make sense to add a pointer from the generic one to the GHC one done - And perhaps some of the material on the GHC page is actually generic, and should be moved? current ghc material is step-by-step recipe of implementing one particular application and i think that another description should be written if we want split it into ghc-specific and common parts moreover, i bet that there are not too much non-ghc FFI users, so it will be hard and almost useless to work on such splitting :( -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Basic FFI with GHC
Ronald Guida wrote:
How do I create C-libraries that I can load into GHCi? I am trying to
do some basic FFI, and it's not working.
So, after more searching on the internet and some RTFM, I think I
found my answer, and it seems to work, but I don't know if it's the
right answer to generalize from.
1. I can leave test_foo.lhs and foo.cpp as-is.
2. I need to change foo.h to the following:
--
// foo.h
#if BUILD_DLL
#define DECLSPEC __declspec(dllexport)
#else
#define DECLSPEC __declspec(dllimport)
#endif
extern C
{
DECLSPEC __stdcall int foo(int x);
}
--
3. I need to create a DEF file and list the functions to be exported
in a DLL.
--
foo.def
--
LIBRARY foo
DESCRIPTION Foo Library
EXPORTS
foo
--
Note: The library name on the first line must match the dll name.
LIBRARY foo corresponds to foo.dll
4. The build process is as follows.
(1) gcc -DBUILD_DLL -c foo.cpp
(2) gcc -shared -o foo.dll foo.o foo.def \
-Wl,--enable-stdcall-fixup,--out-implib,libfoo.a
5. At this point, I'll have foo.dll and libfoo.a. I can load my
foo library, as a DLL, into GHCi with the command:
$ ghci -lfoo
In reality, I would use:
$ ghci test_foo.lhs -lfoo
6. Once I'm satisfied and ready to compile:
ghc --make test_foo.lhs -L. -lfoo
Notes:
(1) -L. directs GHC to look in the current directory for
libraries. GHCi seems to look there by default.
(2) The resulting test_foo.exe will dynamicly load foo.dll.
7. If I want a staticly linked executable instead:
ar rcs libfoo_static.a foo.o
ghc --make test_foo.lhs -L. -lfoo_static
8. Finally, I can put the build steps into a makefile.
--
# Makefile for foo
test_foo.exe : test_foo.lhs libfoo.a foo.dll
ghc --make test_foo.lhs -L. -lfoo
test_foo_static.exe : test_foo.lhs libfoo_static.a
ghc --make test_foo.lhs -L. -lfoo_static -o test_foo_static.exe
libfoo.a : foo.dll
foo.dll : foo.o foo.def
gcc -shared -o foo.dll foo.o foo.def \
-Wl,--enable-stdcall-fixup,--out-implib,libfoo.a
libfoo_static.a : foo.o
ar rcs libfoo_static.a foo.o
foo.o : foo.cpp foo.h
gcc -DBUILD_DLL -c foo.cpp
.PHONY: clean
clean:
rm -f *.[oa]
rm -f *.dll
rm -f *.hi
rm -f *.exe
--
-- Ron
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Re[2]: [Haskell-cafe] Basic FFI with GHC
Hello Ronald, Wednesday, September 12, 2007, 11:18:05 PM, you wrote: So, after more searching on the internet and some RTFM, I think I found my answer, and it seems to work, but I don't know if it's the right answer to generalize from. i have added your recipe to http://www.haskell.org/haskellwiki/FFI_cook_book -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Basic FFI with GHC
How do I create C-libraries that I can load into GHCi? I am trying to
do some basic FFI, and it's not working.
Here's the background. I created three files, foo.h, foo.cpp, and
test_foo.lhs. (source code below)
Note: I am using MinGW/Msys under Windows XP.
If I compile foo.cpp and then try to load test_foo into GHCi, I get an
error. OTOH, if I compile test_foo with GHC, it works. I just don't
understand why it works one way and not the other.
What am I doing wrong?
-- Ron
--
Shell commands
--
$ gcc -c foo.cpp
$ ghci test_foo.lhs foo.o
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 6.6.1, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\/\/ /_/\/|_| Type :? for help.
Loading package base ... linking ... done.
Loading object (static) foo.o ... done
final link ... done
[1 of 1] Compiling Main ( test_foo.lhs, interpreted )
During interactive linking, GHCi couldn't find the following symbol:
foo
This may be due to you not asking GHCi to load extra object files,
[snip]
$ ghc --make test_foo.lhs foo.o
[1 of 1] Compiling Main ( test_foo.lhs, test_foo.o )
Linking test_foo.exe ...
$ test_foo.exe
Entering main
y = 22
Exiting main
$ ar rcs libfoo.a foo.o
$ ghc --make test_foo.lhs -lfoo
$ test_foo.exe
Entering main
y = 22
Exiting main
$ ghci test_foo.lhs -lfoo
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 6.6.1, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\/\/ /_/\/|_| Type :? for help.
Loading package base ... linking ... done.
Loading object (dynamic) foo ... failed.
Dynamic linker error message was:
addDLL: unknown error
Whilst trying to load: (dynamic) foo
Directories to search are:
: user specified .o/.so/.DLL could not be loaded.
--
Source code
--
// foo.h
extern C
{
__stdcall int foo(int x);
}
--
// foo.cpp
#include foo.h
__stdcall int foo(int x)
{
return 3 * x + 1;
}
--
test_foo.lhs
{-# OPTIONS_GHC -fglasgow-exts #-}
module Main
where
import Foreign
import Foreign.C
foreign import stdcall unsafe foo
c_Foo :: Word32 - IO Word32
main = do
putStrLn Entering main
let x = 7::Word32
y - c_Foo(x)
putStrLn $ y = ++ show y
putStrLn Exiting main
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