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storing variable arguments for future use

Hi,

I'm trying to implement delayed function execution,
similar to OpenGL's display lists. It looks something
like this:

beginList ();
fcn1 ();
fcn2 ();
Nov 14 '05 #1
4 1747
matevz bradac <ma*****@email.si> spoke thus:
When execList() is called, fcnToCall (numArgs, ...) should
be executed. The problem is, how do I store variable args
for future use? I know they're all long ints, so this should
be somehow helpful, but I can't figure it out. Do I have to
remember/copy the stack and is this possible in C, or must it
be done in assembly?


Have you looked at the functions in <stdarg.h>? They sound like
they'd help you a lot.

--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cyberspace.org | don't, I need to know. Flames welcome.
Nov 14 '05 #2
"matevz bradac" <ma*****@email.si> wrote in message
news:cc**************************@posting.google.c om...
[snip]
When execList() is called, fcnToCall (numArgs, ...) should
be executed. The problem is, how do I store variable args
for future use? I know they're all long ints, so this should
be somehow helpful, but I can't figure it out. Do I have to
remember/copy the stack and is this possible in C, or must it
be done in assembly?


Assembly is probably the only way to do exactly what you describe,
unfortunately. Using the functions in <stdarg.h>, you could store a
suitably-sized array of the longs (when creating the function list), but
that wouldn't help much as there's no way in standard C to construct the
call to the variadic function.
Nov 14 '05 #3

In article <c5************@ID-149533.news.uni-berlin.de>, "Alex" <me@privacy.net> writes:
"matevz bradac" <ma*****@email.si> wrote in message
news:cc**************************@posting.google.c om...
[snip]
When execList() is called, fcnToCall (numArgs, ...) should
be executed. The problem is, how do I store variable args
for future use?


Assembly is probably the only way to do exactly what you describe,
unfortunately. Using the functions in <stdarg.h>, you could store a
suitably-sized array of the longs (when creating the function list), but
that wouldn't help much as there's no way in standard C to construct the
call to the variadic function.


I couldn't tell from the OP's description, but this might be another
case where the problem can be solved by implementing the real function
as a non-variadic one with a variadic wrapper. That is:

int fcnToCallV(long numArgs, va_list Args);

int fcnToCall(long numArgs, ...)
{
va_list Args;
int Ret;

va_start(Args, numArgs);
Ret = fcnToCallV(numArgs, Args);
va_end(Args);

return Ret;
}

(The OP didn't mention a return type for these functions, so I assumed
int.)

Then the OP's call-list system stores a call to fcnToCall as one to
fcnToCallV, by doing the va_start before storing it and the va_end
when processing the list, after the call returns.

--
Michael Wojcik mi************@microfocus.com

The movie culminated with a bit of everything. -- Jeremy Stephens
Nov 14 '05 #4
This is exactly what I want. I was hoping there's an easy
way of, well, memcpy()-ing the stack, and then passing it
to some function... -> assembly it will have to be.

Thanks,
matevz

"Alex" <me@privacy.net> wrote in message news:<c5************@ID-149533.news.uni-berlin.de>...
Assembly is probably the only way to do exactly what you describe,
unfortunately. Using the functions in <stdarg.h>, you could store a
suitably-sized array of the longs (when creating the function list), but
that wouldn't help much as there's no way in standard C to construct the
call to the variadic function.

Nov 14 '05 #5

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