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digitalmars.D - Call C (or C++) with pointer to static function

reply Michael Stover <michael.r.stover gmail.com> writes:
I am wondering if D would be a good choice for our differential equation
modeling app.  What it needs to be able to do is dynamically compile D code
into a static function that can then be used to call C-code that expects a
pointer to a static function.

Longer description:
It is a desktop app.  The user writes equations.  I'd like to be translate
the equations into D code, compile it, and then call C code that represents
optimizing or solver procedures.  These functions expect a pointer to a
static function that calculates the values of the equations, which would be
the D code just compiled.

Is this feasible with D2?

Thanks,
Michael Stover
Oct 10 2010
parent reply "Simen kjaeraas" <simen.kjaras gmail.com> writes:
On Sun, 10 Oct 2010 22:03:51 +0200, Michael Stover  
<michael.r.stover gmail.com> wrote:


 I am wondering if D would be a good choice for our differential equation
 modeling app.  What it needs to be able to do is dynamically compile D  
 code
 into a static function that can then be used to call C-code that expects  
 a
 pointer to a static function.

 Longer description:
 It is a desktop app.  The user writes equations.  I'd like to be  
 translate
 the equations into D code, compile it, and then call C code that  
 represents
 optimizing or solver procedures.  These functions expect a pointer to a
 static function that calculates the values of the equations, which would  
 be
 the D code just compiled.

 Is this feasible with D2?


Absolutely. The dynamic compilation part is not directly supported, but
possible. There are several ways of accomplishing this, from Burton
Radon's (outdated, proof-of-concept only) dynamic compilation[1], to
calling the C functions in the generated D code, and pipe the output
where you need it.

Interfacing to C is detailed on this page:
http://digitalmars.com/d/2.0/interfaceToC.html

And can mostly be summarized like this:

Create a D function that is callable from C:
extern( C ) returnType myFunc( /* args */ ) {}

Refer to a C function that is callable from D:
extern( C ) returnType myFunc( /* args */ );


[1]:  
http://members.shaw.ca/burton-radons/The%20Joy%20and%20Gibbering%20Terror%20of%20Custom-Loading%20Executables.html

-- 
Simen
Oct 10 2010
next sibling parent reply Michael Stover <michael.r.stover gmail.com> writes:
I am under the impression that passing a pointer to a static function (ie,
passing a pointer to a memory address that contains the starting point of a
function) is not the same as defining a method that can be called by name
from C code.  I am not a C expert though.

Can one call fortran libraries from D?  Ie, say one wanted to use LAPACK
from D?

Also, know of any mathematical libraries written in D (like implementations
of runge-kutta, linear algebra routines and data structures, optimization or
curve-fitting algorithms)?

-Mike



On Sun, Oct 10, 2010 at 5:10 PM, Simen kjaeraas <simen.kjaras gmail.com>wrote:


 On Sun, 10 Oct 2010 22:03:51 +0200, Michael Stover <
 michael.r.stover gmail.com> wrote:

  I am wondering if D would be a good choice for our differential equation

 modeling app.  What it needs to be able to do is dynamically compile D
 code
 into a static function that can then be used to call C-code that expects a
 pointer to a static function.

 Longer description:
 It is a desktop app.  The user writes equations.  I'd like to be translate
 the equations into D code, compile it, and then call C code that
 represents
 optimizing or solver procedures.  These functions expect a pointer to a
 static function that calculates the values of the equations, which would
 be
 the D code just compiled.

 Is this feasible with D2?


 Absolutely. The dynamic compilation part is not directly supported, but
 possible. There are several ways of accomplishing this, from Burton
 Radon's (outdated, proof-of-concept only) dynamic compilation[1], to
 calling the C functions in the generated D code, and pipe the output
 where you need it.

 Interfacing to C is detailed on this page:
 http://digitalmars.com/d/2.0/interfaceToC.html

 And can mostly be summarized like this:

 Create a D function that is callable from C:
 extern( C ) returnType myFunc( /* args */ ) {}

 Refer to a C function that is callable from D:
 extern( C ) returnType myFunc( /* args */ );


 [1]:
 http://members.shaw.ca/burton-radons/The%20Joy%20and%20Gibbering%20Terror%20of%20Custom-Loading%20Executables.html

 --
 Simen
Oct 10 2010
next sibling parent reply "Simen kjaeraas" <simen.kjaras gmail.com> writes:
Michael Stover <michael.r.stover gmail.com> wrote:


 I am under the impression that passing a pointer to a static function  
 (ie,
 passing a pointer to a memory address that contains the starting point  
 of a
 function) is not the same as defining a method that can be called by name
 from C code.  I am not a C expert though.


Well, yes and no. Given

extern( C ) returnType myFunc( /* args */ ) {}

You still have no function pointer to it. That is however easy to procure:

someCfunctionThatExpectsAfnPointer( &myFunc );

It could be that there is some hidden detail of C static functions that I
don't know, but i believe this works.



 Can one call fortran libraries from D?  Ie, say one wanted to use LAPACK
 from D?


http://dsource.org/projects/scid uses LAPACK, so I guess it is possible.


 Also, know of any mathematical libraries written in D (like  
 implementations
 of runge-kutta, linear algebra routines and data structures,  
 optimization or
 curve-fitting algorithms)?


At least some of this has been mentioned time and time again on the
newsgroup, you should be able to find it by searching.

 From dsource.org/projects:

http://dsource.org/projects/scid
http://dsource.org/projects/dstats

-- 
Simen
Oct 11 2010
parent Michael Stover <michael.r.stover gmail.com> writes:
Thank you for helping me understand.

Mike

On Mon, Oct 11, 2010 at 8:39 AM, Simen kjaeraas <simen.kjaras gmail.com>wrote:


 Michael Stover <michael.r.stover gmail.com> wrote:

  I am under the impression that passing a pointer to a static function (ie,

 passing a pointer to a memory address that contains the starting point of
 a
 function) is not the same as defining a method that can be called by name
 from C code.  I am not a C expert though.


 Well, yes and no. Given


 extern( C ) returnType myFunc( /* args */ ) {}

 You still have no function pointer to it. That is however easy to procure:

 someCfunctionThatExpectsAfnPointer( &myFunc );

 It could be that there is some hidden detail of C static functions that I
 don't know, but i believe this works.



  Can one call fortran libraries from D?  Ie, say one wanted to use LAPACK

 from D?


 http://dsource.org/projects/scid uses LAPACK, so I guess it is possible.


  Also, know of any mathematical libraries written in D (like

 implementations
 of runge-kutta, linear algebra routines and data structures, optimization
 or
 curve-fitting algorithms)?


 At least some of this has been mentioned time and time again on the
 newsgroup, you should be able to find it by searching.

 From dsource.org/projects:

 http://dsource.org/projects/scid
 http://dsource.org/projects/dstats

 --
 Simen
Oct 11 2010
prev sibling parent reply "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:
On Sun, 10 Oct 2010 20:30:52 -0400, Michael Stover wrote:
 

 Can one call fortran libraries from D?  Ie, say one wanted to use LAPACK
 from D?


Since it is possible in C, it should be possible in D.  A quick search 
turned up this page:

http://www.yolinux.com/TUTORIALS/LinuxTutorialMixingFortranAndC.html

When it comes to LAPACK (and BLAS), Bill Baxter has already written D1 
bindings.  I've converted them to D2 and published them (with his kind 
permission) as part of SciD (see scid.bindings.*).  Which brings me to 
your next question...



 Also, know of any mathematical libraries written in D (like
 implementations of runge-kutta, linear algebra routines and data
 structures, optimization or curve-fitting algorithms)?


Of the things you mention, SciD only contains a few linear algebra 
routines (see scid.linalg and the aforementioned BLAS/LAPACK bindings).  
There may be other things you'll find useful in there, though:

  http://www.dsource.org/projects/scid

Also, check out this list (may not be up to date):

  http://www.prowiki.org/wiki4d/wiki.cgi?ScientificLibraries


-Lats
Oct 11 2010
parent Michael Stover <michael.r.stover gmail.com> writes:
Thank you, I have checked them out.  Both SciD and dstats look useful.  We
would have to supplement with our own math libraries and bindings to various
C/Fortran libraries I think.   I am just exploring possibilities because of
the endless troubles we have with compiling and linking C++ code on Mac,
Linux, and Windows and thus why we've never compiled our math models (which
makes them really slow).  For estimation problems, it's just not workable
without compiling the model at runtime to native code.  It was my thought
that D would make the step easier and faster than C++.  But is does have to
work on Mac, Windows, and Linux user desktops.

-Mike

On Mon, Oct 11, 2010 at 9:56 AM, Lars T. Kyllingstad
<public kyllingen.nospamnet> wrote:


 On Sun, 10 Oct 2010 20:30:52 -0400, Michael Stover wrote:


 Can one call fortran libraries from D?  Ie, say one wanted to use LAPACK
 from D?


 Since it is possible in C, it should be possible in D.  A quick search
 turned up this page:

 http://www.yolinux.com/TUTORIALS/LinuxTutorialMixingFortranAndC.html

 When it comes to LAPACK (and BLAS), Bill Baxter has already written D1
 bindings.  I've converted them to D2 and published them (with his kind
 permission) as part of SciD (see scid.bindings.*).  Which brings me to
 your next question...



 Also, know of any mathematical libraries written in D (like
 implementations of runge-kutta, linear algebra routines and data
 structures, optimization or curve-fitting algorithms)?


 Of the things you mention, SciD only contains a few linear algebra
 routines (see scid.linalg and the aforementioned BLAS/LAPACK bindings).
 There may be other things you'll find useful in there, though:

  http://www.dsource.org/projects/scid

 Also, check out this list (may not be up to date):

  http://www.prowiki.org/wiki4d/wiki.cgi?ScientificLibraries


 -Lats
Oct 11 2010
prev sibling parent Daniel Gibson <metalcaedes gmail.com> writes:
On Mon, Oct 11, 2010 at 2:30 AM, Michael Stover
<michael.r.stover gmail.com> wrote:

 I am under the impression that passing a pointer to a static function (ie=


,

 passing a pointer to a memory address that contains the starting point of=


 a

 function) is not the same as defining a method that can be called by name
 from C code. =A0I am not a C expert though.
 Can one call fortran libraries from D? =A0Ie, say one wanted to use LAPAC=


K

 from D?
 Also, know of any mathematical libraries written in D (like implementatio=


ns

 of runge-kutta, linear algebra routines and data structures, optimization=


 or

 curve-fitting algorithms)?
 -Mike


See
http://www.digitalmars.com/d/archives/digitalmars/D/Is_there_anybody_workin=
g_on_a_linear_algebra_library_for_D2_118357.html
:-)
Oct 11 2010