Help with ADA and C function pointers.

Help with ADA and C function pointers.

[Wendell P Beckwith]

I have an ada main procedure which needs to pass the address of an ada
function to a C funciton.  Using gnat 3.05 the following compiles and
generates an executable, but it cores when you run it.  I knew it would
because no where am I assigning a function to be passed.  That is what
I'd like to know how to do.  Please respond to my work email, since I'm
not in this group alot.  Thanks!!

Wendell

-- my test main
with Text_IO, Interfaces.C; 
use Text_IO;

Procedure Gmain is

	Function func(d : in Integer) return Integer is
	Begin
		return (2 * d);
	End;
	type func_type is access Function(d : in Integer) return Integer;
	funcptr : func_type;
	
	Procedure Stuff(f : in func_type);
	pragma Import(C, Stuff, "stuff");
	
Begin
	Stuff(funcptr);
End;

-- my test C function using the ada callback
#include <stdio.h>

void stuff(int (*function)(int))
{
	printf("Value = %d\n", (*function)(10));
}

Re: Help with ADA and C function pointers.

[Aaron Quantz]

How about the 'address attribute?
Regards,

Aaron Quantz
Mgr Software Development, TCS
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THANKS! (was Help with ADA and C function pointers.)

[Wendell P Beckwith]

To all those who responded to my post I'd like to say thanks!

Wendell

Re: Help with ADA and C function pointers.

[Stephen Leake]

Wendell P Beckwith wrote:
> 
> [snip]
>
> -- my test main
> with Text_IO, Interfaces.C;
> use Text_IO;
> 
> Procedure Gmain is
> 
>         Function func(d : in Integer) return Integer is
>         Begin
>                 return (2 * d);
>         End;
>         type func_type is access Function(d : in Integer) return Integer;
>         funcptr : func_type;
> 
>         Procedure Stuff(f : in func_type);
>         pragma Import(C, Stuff, "stuff");
> 
> Begin
>         Stuff(funcptr);
> End;
> 

Try:

	Stuff (Func'access);

You don't actually need the funcptr variable.

>  Please respond to my work email, since I'm
> not in this group alot.  Thanks!!
> 
 Sorry, you'll have to read thru the news just like the rest of us; we
hope you'll be able to contribute something!
-- 
- Stephe

Re: Help with ADA and C function pointers.

[fd]

Wendell P Beckwith (wbeckwit@rsa.hisd.harris.com) wrote:
: I have an ada main procedure which needs to pass the address of an ada
: function to a C funciton.  Using gnat 3.05 the following compiles and
: generates an executable, but it cores when you run it.  I knew it would
: because no where am I assigning a function to be passed.  That is what
: I'd like to know how to do.  Please respond to my work email, since I'm
: not in this group alot.  Thanks!!

: Wendell

: -- my test main
: with Text_IO, Interfaces.C; 
: use Text_IO;

: Procedure Gmain is

: 	Function func(d : in Integer) return Integer is
: 	Begin
: 		return (2 * d);
: 	End;
: 	type func_type is access Function(d : in Integer) return Integer;
: 	funcptr : func_type;
Here funcptr value is NULL
: 	
: 	Procedure Stuff(f : in func_type);
: 	pragma Import(C, Stuff, "stuff");
: 	
: Begin
: 	Stuff(funcptr);
there is a problem, funcptr is still equal to NULL
I will try Stuff(func'adress) and you don't need funcptr.
Hope it will help.
: End;

: -- my test C function using the ada callback
: #include <stdio.h>

: void stuff(int (*function)(int))
: {
: 	printf("Value = %d\n", (*function)(10));
: }

 franck.duluc@avions.aerospatiale.fr
		
Regards.	

Re: Help with ADA and C function pointers.

[fd]

Wendell P Beckwith (wbeckwit@rsa.hisd.harris.com) wrote:
: I have an ada main procedure which needs to pass the address of an ada
: function to a C funciton.  Using gnat 3.05 the following compiles and
: generates an executable, but it cores when you run it.  I knew it would
: because no where am I assigning a function to be passed.  That is what
: I'd like to know how to do.  Please respond to my work email, since I'm
: not in this group alot.  Thanks!!

: Wendell

: -- my test main
: with Text_IO, Interfaces.C; 
: use Text_IO;

: Procedure Gmain is

: 	Function func(d : in Integer) return Integer is
: 	Begin
: 		return (2 * d);
: 	End;
: 	type func_type is access Function(d : in Integer) return Integer;
: 	funcptr : func_type;
Here funcptr value is NULL
: 	
: 	Procedure Stuff(f : in func_type);
: 	pragma Import(C, Stuff, "stuff");
: 	
: Begin
: 	Stuff(funcptr);
there is a problem, funcptr is still equal to NULL
I will try Stuff(func'adress) and you don't need funcptr.
Hope it will help.
: End;

: -- my test C function using the ada callback
: #include <stdio.h>

: void stuff(int (*function)(int))
: {
: 	printf("Value = %d\n", (*function)(10));
: }

 franck.duluc@avions.aerospatiale.fr
		
Regards.