[Mspgcc-users] Calling constructors (C++) manually with mspgcc4
Dear list,
I'm currently trying to port a project (using C++) from mspgcc (3.2.3)
to mspgcc4. It is a generic C++ library, running (among other systems)
on top of Contiki (which is a C-based firmware/OS).
As far as I know, constructors of global C++ objects are not called
automatically, so that the user must call them manually. So far I did
this successfully via
typedef void(*ctor_t)();
extern ctor_t __ctors_start;
extern ctor_t __ctors_end;
...
ctor_t ctor = __ctors_start;
while( ctor __ctors_end )
{
ctor();
ctor = (ctor_t)((void*)ctor + sizeof(void*));
}
However, compiling the project with mspgcc4, it doesn't work anymore.
Printing addresses of ctors_start/end via
printf( Call ctors from %04x to %04x\n,
(unsigned int)*__ctors_start,
(unsigned int)*__ctors_end );
produces a higher number for ctors start address than for the end
(looking in the *.map-file, everything looks fine).
Do I understand sth wrong (so, is the above code incorrect, and it
worked on the 3.2.3 just by luck)? Do you have an idea, how I should
call the constructors?
Or is the information above incomplete - then please let me know!
Best,
Tobias
--
Nokia and ATT present the 2010 Calling All Innovators-North America contest
Create new apps games for the Nokia N8 for consumers in U.S. and Canada
$10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing
Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
http://p.sf.net/sfu/nokia-dev2dev
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Re: [Mspgcc-users] Calling constructors (C++) manually with mspgcc4
Constructors for global C++ objects should be called automatically, as long
as you're not doing something in the link phase that disrupts things. My
testing with the program below shows that it seems to work. Note that if
you fall off the end of main(), the global dtors are called.
0x1c00#global ctor
0x2bfe#local ctor
In main
0x2bfe#local dtor
0x1c00#global dtor
Peter
#include stdio.h
class CtorDtor {
public:
CtorDtor (const char* id) :
id_(id)
{
printf(%p#%s ctor\r\n, this, id_);
}
~CtorDtor ()
{
printf(%p#%s dtor\r\n, this, id_);
}
private:
const char* id_;
};
CtorDtor global(global);
int main ()
{
CtorDtor local(local);
printf(In main\r\n);
return 0;
}
On Wed, Oct 20, 2010 at 9:48 AM, Tobias Baumgartner
tb...@ibr.cs.tu-bs.dewrote:
Dear list,
I'm currently trying to port a project (using C++) from mspgcc (3.2.3)
to mspgcc4. It is a generic C++ library, running (among other systems)
on top of Contiki (which is a C-based firmware/OS).
As far as I know, constructors of global C++ objects are not called
automatically, so that the user must call them manually. So far I did
this successfully via
typedef void(*ctor_t)();
extern ctor_t __ctors_start;
extern ctor_t __ctors_end;
...
ctor_t ctor = __ctors_start;
while( ctor __ctors_end )
{
ctor();
ctor = (ctor_t)((void*)ctor + sizeof(void*));
}
However, compiling the project with mspgcc4, it doesn't work anymore.
Printing addresses of ctors_start/end via
printf( Call ctors from %04x to %04x\n,
(unsigned int)*__ctors_start,
(unsigned int)*__ctors_end );
produces a higher number for ctors start address than for the end
(looking in the *.map-file, everything looks fine).
Do I understand sth wrong (so, is the above code incorrect, and it
worked on the 3.2.3 just by luck)? Do you have an idea, how I should
call the constructors?
Or is the information above incomplete - then please let me know!
Best,
Tobias
--
Nokia and ATT present the 2010 Calling All Innovators-North America
contest
Create new apps games for the Nokia N8 for consumers in U.S. and Canada
$10 million total in prizes - $4M cash, 500 devices, nearly $6M in
marketing
Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
http://p.sf.net/sfu/nokia-dev2dev
___
Mspgcc-users mailing list
Mspgcc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/mspgcc-users
--
Nokia and ATT present the 2010 Calling All Innovators-North America contest
Create new apps games for the Nokia N8 for consumers in U.S. and Canada
$10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing
Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
http://p.sf.net/sfu/nokia-dev2dev___
Mspgcc-users mailing list
Mspgcc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/mspgcc-users
Re: [Mspgcc-users] Calling constructors (C++) manually with mspgcc4
Hmmm, what is the definition of __ctors_start?
I doubt it is an extern variable pointer to void. It is a constant value. Or
more precisely it is no lvalue. There is no memory location where its value is
stored. It just has a value, is a linker generated 'constant' reference.
But by your extern definition, the compiler doesn't know this. It assumes that
it is a normal pointer variable. So later, when you use __ctors_start, the
compiler uses an additional inference, as the value of a variable is
the value stored at the location it references, not the value it actually HAS.
In other words (example):
if __ctors_start is 0x5c00, the line
ctor_t ctor = __ctors_start; results in
mov 0x5c00, ctor;
moving the value at the begin of Flash into your ctor variable as new pointer,
while what you want is a
mov #0x5c00, ctor;
moving the VALUE of __ctors_start as new pointer into ctor.
So use __ctors_start when you want the address __ctors_start points to (the
value of __ctors_start).
JMGross
- Ursprüngliche Nachricht -
Von: Tobias Baumgartner
Gesendet am: 20 Okt 2010 16:48:55
I'm currently trying to port a project (using C++) from mspgcc (3.2.3)
to mspgcc4. It is a generic C++ library, running (among other systems)
on top of Contiki (which is a C-based firmware/OS).
As far as I know, constructors of global C++ objects are not called
automatically, so that the user must call them manually. So far I did
this successfully via
typedef void(*ctor_t)();
extern ctor_t __ctors_start;
extern ctor_t __ctors_end;
...
ctor_t ctor = __ctors_start;
while( ctor __ctors_end )
{
ctor();
ctor = (ctor_t)((void*)ctor + sizeof(void*));
}
However, compiling the project with mspgcc4, it doesn't work anymore.
Printing addresses of ctors_start/end via
printf( Call ctors from %04x to %04x\n,
(unsigned int)*__ctors_start,
(unsigned int)*__ctors_end );
produces a higher number for ctors start address than for the end
(looking in the *.map-file, everything looks fine).
Do I understand sth wrong (so, is the above code incorrect, and it
worked on the 3.2.3 just by luck)? Do you have an idea, how I should
call the constructors?
Or is the information above incomplete - then please let me know!
Best,
Tobias
--
Nokia and ATT present the 2010 Calling All Innovators-North America contest
Create new apps games for the Nokia N8 for consumers in U.S. and Canada
$10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing
Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
http://p.sf.net/sfu/nokia-dev2dev
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