Re: Trouble figuring out DirectCall interface

Ok, the doc string is not involved, this good to know.

I'm still trying to figure out what went wrong when calling 
CormanLispServer from an InprocServer.

Thanks for the heads up, Roger.

Wayne Rogers


--- In [email protected], Roger Corman <roger@c...> wrote:
> Wayne,
> 
> I am glad you got it working. One thing, though. The doc string 
should have absolutely no effect on the generated code, and the FFI 
certainly does not get the return type from it. Actually the returned 
type is based on the lisp value returned, so you have to be careful. 
It is not in the declaration.
> 
> If you return an integer, it returns a 32-bit signed integer. If 
you return a float, it will return a single or double float as 
appropriate. If you return a pointer to a foreign block, it returns a 
pointer. As is typical in a language like C, you need to be careful 
that whoever allocates a foreign block also deallocates it. You 
shouldn't return a heap block from corman lisp that is allocated with 
ct:malloc, because that has a hook that causes it to get freed when 
the pointer object gets garbage collected. If you need to allocate a 
block and return it, there are many OS calls or C language calls that 
can be used directly, as long as you are sure to free them in your 
non-lisp code afterward.
> 
> There is code in sys/context-menu.lisp that uses the direct call 
interface, and from which you can get some examples. They also don't 
have doc strings. Whatever caused the system to start working for 
you, it must have been something other than the doc string.
> 
> Roger
> 
> At 07:32 PM 10/2/2003, you wrote:
> >Problem solved.
> >
> >I started out creating an ATL project in VC6. I remembered from 
> >somewhere that it had to be done in VC7 so I switch to that (a 
free 
> >download with the Microsoft .Net Framework SDK).
> >
> >I made a copy of the clbootapp project and loaded it into VC7. I 
> >added code to create an instance of the ICormanLispDirectCall and 
did 
> >the Bless, Initialize, etc. The GetFunctionAddress call succeeds 
but 
> >I was getting a null function pointer to my lisp function. I 
figured 
> >out the lisp function and package names are case sensitive. 
> >Presumably the exported function will always be upper case because 
> >that's how they appear when the lisp evaluation prints it. The 
> >package name looks the same way that I specified it in the lisp 
> >environment.
> >
> >The last piece of the puzzle was that the return type has to be 
> >specified like a documentation string, which I guessed based upon 
an 
> >example shown in the user guide for the defun-callback function.
> >
> >So my working sample now looks like this:
> >
> >;; lisp 
> >(in-package "math1")
> >
> >(ct:defun-direct-callback add2numbers ((a win32:long)(b 
win32:long))
> >    "long __stdcall add(long a, long b)"
> >     (+ a b))
> >
> >(export '(add2numbers))
> >
> >(save-image "math.img")
> >
> >
> >// C++
> >typedef long (__stdcall *pfAdd)(long a, long b);
> >pfAdd adder;
> >
> >HRESULT hr = m_iLispCall->GetFunctionAddress
(L"ADD2NUMBERS",L"math1",
> >(LPVOID*)&adder);
> >
> >long sum = adder(13, 12);
> >
> >
> >I hope this may help someone later on down the road.
> >
> >Thanks to Chris and Roger for your patience,
> >Wayne Rogers
> >
> >
> >P.S. does the new version of CCL have an updated manual?
> >
> >--- In [email protected], "goobamarino" 
<goobamarino@y...> 
> >wrote:
> >> The m_iLispCall is an instance of ICormanLispDirectCall. When I 
> >> debug in VC it shows the stack trace going into the CormanLisp 
> >> server.
> >> 
> >> Do I need to do anything besides the following?:
> >>    ;; lisp
> >>    ct:defun-direct-callback
> >>    save-image
> >>    // C++
> >>    create direct call object
> >>    GetFunctionAddress
> >> 
> >> I'm not claiming anything wrong with CormanLisp, I'm just trying 
to 
> >> figure out where I'm going wrong.
> >> 
> >> TIA,
> >> Wayne Rogers
> >> 
> >> P.S. I can post all the VC code if it may help diagnosis.
> >> 
> >> --- In [email protected], "Chris Double" 
> >> <chris.double@d...> wrote:
> >> > On Wed, 01 Oct 2003 02:49:40 -0000, "goobamarino" 
> >> <goobamarino@y...>
> >> > said:
> >> > > > >                HRESULT hr = m_iLispCall-
>GetFunctionAddress
> >> > > > >(L"ADD2NUMBERS",L"WIN32",(LPVOID*)&m_pfAdder);
> >> > 
> >> > What is the value of m_iLispCall here? Is that pointer valid? 
Are 
> >> you
> >> > sure it's inside GetFunctionAddress that is crashing or could 
it 
> >> be an
> >> > invalid m_iLispCall causing GetFunctionAddress to do things 
> >inside 
> >> of an
> >> > invalid object?
> >> > 
> >> > Chris.
> >> > -- 
> >> >   Chris Double
> >> >   chris.double@d...
> >
> >
> >
> >To unsubscribe from this group, send an email to:
> >[email protected]
> >
> > 
> >
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