1. How to deal with C_POINTR?
when define and call c_func often there are parameters passed by
pointers, then how to send and get data if it is a c struct?
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C#, Euphoria,Python, Haskell, Curry
2. Re: How to deal with C_POINTR?
>when define and call c_func often there are parameters passed by
>pointers, then how to send and get data if it is a c struct?
Let's say you have:
typedef struct
{
int a,b;
} foo;
foo *bar(foo *grill)
{
return grill;
}
Then you could do something like:
constant FOO_A=0, FOO_B=4, SIZEOF_FOO=8
constant grill = allocate(SIZEOF_FOO)
constant bar = define_c_func(blah,"bar",{C_POINTER},C_POINTER)
grill = c_func(bar,{grill})
? peek4s(grill+FOO_B) -- print grill->b
3. Re: How to deal with C_POINTR?
----- Original Message -----
From: <stabmaster_ at hotmail.com>
To: "EUforum" <EUforum at topica.com>
Subject: Re: How to deal with C_POINTR?
>
> >when define and call c_func often there are parameters passed by
> >pointers, then how to send and get data if it is a c struct?
>
> Let's say you have:
>
> typedef struct
> {
> int a,b;
> } foo;
>
> foo *bar(foo *grill)
> {
> return grill;
> }
The problem though is when you have something like ...
foo bar(foo grill)
{
return grill;
}
In other words, the struct is passed by value, not as a pointer to struct.
In this case, it is difficult. Sometimes, if the stuct ONLY has 32-bit
values in it, you can fake passing it as a set of C_UINT values, but
returning a struct is impossible, I suspect.
----------------
cheers,
Derek Parnell
4. Re: How to deal with C_POINTR?
I guess you could receive a structure using some assembly code, though i
don't know how structs are returned by value. Can't exactly put in a
register, so the stack would be probable.. Anyway, I can't see in what
situation anyone would like to pass/return structs by value. If it's a dll
written by someone else and you have the source code, then by all means fix
it to do it the proper way (i.e. using pointers).
> > >when define and call c_func often there are parameters passed by
> > >pointers, then how to send and get data if it is a c struct?
> >
> > Let's say you have:
> >
> > typedef struct
> > {
> > int a,b;
> > } foo;
> >
> > foo *bar(foo *grill)
> > {
> > return grill;
> > }
>
>The problem though is when you have something like ...
>
> foo bar(foo grill)
>{
> return grill;
>}
>
>In other words, the struct is passed by value, not as a pointer to struct.
>
>In this case, it is difficult. Sometimes, if the stuct ONLY has 32-bit
>values in it, you can fake passing it as a set of C_UINT values, but
>returning a struct is impossible, I suspect.
>
5. Re: How to deal with C_POINTR?
> If it's a dll written by someone else and you have the source code,
> then by all means fix it to do it the proper way (i.e. using pointers).
It's like I always say, "Work with the system, people!"
