1. Call-backs
I'm calling functions in a dll... one of them takes a pointer to this
struct as a parameter.
<c code>
typedef struct dsFunctions {
int version; /* put DS_VERSION here */
/* version 1 data */
void (*start)(); /* called before sim loop starts */
void (*step) (int pause); /* called before every frame */
void (*command) (int cmd); /* called if a command key is pressed */
void (*stop)(); /* called after sim loop exits */
/* version 2 data */
char *path_to_textures; /* if nonzero, path to texture files */
} dsFunctions;
</c code>
The C test program does this:
<c code>
// setup pointers to callback functions
dsFunctions fn;
fn.version = DS_VERSION;
fn.start = &start;
fn.step = &simLoop;
fn.command = command;
fn.stop = 0;
fn.path_to_textures = 0; // uses default
</c code>
start is "void start()",
simLoop is "void simLoop(int pause)",
command is "void command(int cmd)"
(minor) why is fn.command assigned command directly, not &command?
What size are each of those elements in the function, and what do I
have to poke into the call_back spaces? The return value from
call_back()?
--
MrTrick
2. Re: Call-backs
- Posted by Patrick Barnes <mrtrick at gmail.com>
Feb 15, 2005
-
Last edited Feb 16, 2005
On Tue, 15 Feb 2005 17:49:03 -0500, Elliott Sales de Andrade wrote:
> 4 bytes, yes.
Thanks.
> PS. I thought we were working on this, eh?
Indeed, this is for the drawstuff library. I haven't seen you on
#euphoria since I managed to build the dll.
--
MrTrick
3. Re: Call-backs
On Tue, 15 Feb 2005 21:33:17 +1100, Patrick Barnes <mrtrick at gmail.com> wrote:
> I'm calling functions in a dll... one of them takes a pointer to this
> struct as a parameter.
>
> <c code>
> typedef struct dsFunctions {
> int version; /* put DS_VERSION here */
> /* version 1 data */
> void (*start)(); /* called before sim loop starts */
> void (*step) (int pause); /* called before every frame */
> void (*command) (int cmd); /* called if a command key is pressed */
> void (*stop)(); /* called after sim loop exits */
> /* version 2 data */
> char *path_to_textures; /* if nonzero, path to texture files */
> } dsFunctions;
> </c code>
>
> The C test program does this:
> <c code>
> // setup pointers to callback functions
> dsFunctions fn;
> fn.version = DS_VERSION;
> fn.start = &start;
> fn.step = &simLoop;
> fn.command = command;
> fn.stop = 0;
> fn.path_to_textures = 0; // uses default
> </c code>
>
> start is "void start()",
> simLoop is "void simLoop(int pause)",
> command is "void command(int cmd)"
>
> (minor) why is fn.command assigned command directly, not &command?
>
> What size are each of those elements in the function, and what do I
> have to poke into the call_back spaces? The return value from
> call_back()?
Hmm, this doesn't work properly... the return-type of the functions in
the struct is void (isn't it?), but Euphoria won't let me use
call_back() on a procedure.
What to do?
--
MrTrick
4. Re: Call-backs
Patrick Barnes wrote:
>
> Hmm, this doesn't work properly... the return-type of the functions in
> the struct is void (isn't it?), but Euphoria won't let me use
> call_back() on a procedure.
>
> What to do?
Just declare it a function, and return zero or something, and the compiled
code will ignore the return value.
Matt Lewis
