#19222 - Krakken - Wed Apr 14, 2004 7:23 am
Hi,
For some reason when I declare a class with initialiser parameters outside of a function, whether this be main() or any other, the constructor is not executed.
Example:
| Code: |
// IMAGINE THE CONSTRUCTOR SETS cValue AS THE INITIAL PARAMETER
// WORKS //
int main() {
class_object class_name ('A'); // class_name.cValue is set to 'A'
while (true);
return 0;
}
// DOES NOT WORK //
class_object class_name ('A'); // class_name.cValue is not set to anything
int main() {
while (true);
return 0;
}
|
Any ideas why?
#19224 - f(DarkAngel) - Wed Apr 14, 2004 11:45 am
In C, globals should be assigned staticaly, in bss. If you want compiler to execute a function at compile time, use macros.
It worked without any problems with the standard (x86) GCC in Linux. It might be a init execution problem of the start up code (Jeff Frohwein?). With a simple logic, your (run-time) program execution starts at main, not global inits.
_________________
death scream...
#19226 - torne - Wed Apr 14, 2004 4:01 pm
Commonly available link scripts (the one in DKA and Jeff's) should execute constructors correctly for globals but you may need to turn on C++ support in the crt0 file. This enables the code that runs the .ctors entries.
#19233 - sajiimori - Wed Apr 14, 2004 9:22 pm
No offense f(DarkAngel), but your post is kinda nonsense. Executing functions at compile time?? This ain't Lisp ya know. :)
#19243 - tepples - Thu Apr 15, 2004 5:52 am
Though it's not as powerful in practice as Lisp's, the C++ preprocessor is said to be Turing complete.
_________________
-- Where is he?
-- Who?
-- You know, the human.
-- I think he moved to Tilwick.
#19255 - f(DarkAngel) - Thu Apr 15, 2004 12:04 pm
| sajiimori wrote: |
| No offense f(DarkAngel), but your post is kinda nonsense. Executing functions at compile time?? This ain't Lisp ya know. :) |
#define SOMEVALUE_SET(x) ((x) >> 4)
#define GLOBAL_SOMETHING (*((vu16*)0x4543523412))
GLOBAL_SOMETHING = SOMEVALUE_SET(5);
A macro is what i intended with "complie time function". A macro can be written without violating the mathematical meaning of the "function". Is this non-sense?
_________________
death scream...
#19258 - poslundc - Thu Apr 15, 2004 2:43 pm
Actually, that example is nonsense. You can't place executable code like that outside of a function.
Dan.
#19266 - f(DarkAngel) - Thu Apr 15, 2004 5:06 pm
Of course it's not possible to implement that example outside of a function. It's very normal for some to intentionally miss the true intesion of a sentence, even though there's an explanation in the previous/next sentence; both of my posts.. I have seen this kind in communities i have been, internet either real life, and naturally this community cannot be an exception.
This example has no assertion that the code is inside of a function. It emphasizes that a functionality can be executed by compiler, a reply to the previous post, "Executing functions at compile time??". If it's going to statisfy your insatible ego:
int my_global = SOMEVALUE_SET(5);
is valid in global scope.
The discussions you poslundc and sajiimori have started are off-topic, and this is what is non-sense.
Yes poslundc , i am non-sense, yes i am idiot and ignorant, yes you are the greatest. If you don't have anything to say about the actual purpose, question of this thread, don't reply. Case ended.
_________________
death scream...
#19269 - poslundc - Thu Apr 15, 2004 7:20 pm
| f(DarkAngel) wrote: |
| If you don't have anything to say about the actual purpose, question of this thread, don't reply. Case ended. |
I'm sorry, I thought this thread was about initializing objects in global space. I don't know where I got that idea from.
Dan.
#19567 - wintermute - Thu Apr 22, 2004 2:42 am
| Krakken wrote: |
Hi,
For some reason when I declare a class with initialiser parameters outside of a function, whether this be main() or any other, the constructor is not executed.
Any ideas why? |
most GBA crtls don't support global constructors. The only exception is the set built in to devkitARM - http://www.devkit.tk .
Documentation and examples are still being worked on so apologies for a lack of information at present.
Code should be linked using arm-elf-g++ -specs=gba.specs -o <output>.elf <object list>
please feel free to join the mailing list detailed on the about page for any queries you may have.
#19568 - wintermute - Thu Apr 22, 2004 2:45 am
| torne wrote: |
| Commonly available link scripts (the one in DKA and Jeff's) should execute constructors correctly for globals but you may need to turn on C++ support in the crt0 file. This enables the code that runs the .ctors entries. |
This is not the case, the CPP support only changes the name of the main function. With the arm-elf target this is not enough to enable global constructors.
#19581 - torne - Thu Apr 22, 2004 11:16 am
The crt0 I use executes the _ctors section just fine.. it claims to be Jeff's. Perhaps someone else modified it.. I forget where I downloaded it from.