Thread calling function from class problem

[Ghoti]

Hi folks,

I am trying to create a simple loadingscreen function. I do it with the sceKernelCreateThread function which create the loading sequence rendering code while the main thread remains loading up models/pictures/variable/files etc....

anyway... that was the idea :) As in the past I have some problem regarding function pointers and the like.

The second parameter of the function sceKernelCreateThread is pointer to a function. I try to do it like this:

Code: Select all

LoadingScreen::LoadingScreen() {
	// the loadingscreen is loaded
	thid_ = sceKernelCreateThread("LoadingThread", this->RunLoadingScreen(), 0x18, 0x10000, 0, NULL);
}


void LoadingScreen::KillLoadingScreen() {
	// shut down the loading screen again.
	sceKernelDeleteThread(thid_);
}

void LoadingScreen::RunLoadingScreen() {
	
	while(1) {
		// render loading screen


	}

}

Now calling this function returns an error with compiling.

Code: Select all

oadingScreen.cpp: In constructor 'LoadingScreen::LoadingScreen()':
LoadingScreen.cpp:6: error: invalid use of void expression

I remember from before that there is a way of using pointers to functions from classes but I do not know anymore how exactly and I could not find it with google :(

Hope you guys can shed some light on it !

greets Ghoti

[Raphael]

Code: Select all

	thid_ = sceKernelCreateThread("LoadingThread", this->RunLoadingScreen(), 0x18, 0x10000, 0, NULL);

What this line does is call this->RunLoadingScreen() and try to submit its return value (which is void) as the second parameter to sceKernelCreateThread.
What you want to do is this:

Code: Select all

thid_ = sceKernelCreateThread("LoadingThread", RunLoadingScreen, 0x18, 0x10000, 0, NULL);

[Ghoti]

Hi thanks!

you are right but I also had to change the function to a static and like this:

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int LoadingScreen::RunLoadingScreen(SceSize args, void *argp) {

but what I do not understand is why, why does it need the args and argp? why does it have to be an int as return value ? I really want to understand it before I will use it for whatever.

greets ghoti

EDIT::EDIT
Is there a non kernel function for creating and using thread by the way ?

[Cpasjuste]

You can create and start threads in user mode the same way!

[Raphael]

but what I do not understand is why, why does it need the args and argp? why does it have to be an int as return value ?

Because that's the definition of a thread entry function, same as the main program entry function main( ... ).

Is there a non kernel function for creating and using thread by the way ?

sceKernelCreateThread is actually a user function. Just because it starts with sceKernel doesn't mean the function only works in kernel mode.
See the header files in pspsdk\src\user

[Ghoti]

but what I do not understand is why, why does it need the args and argp? why does it have to be an int as return value ?

Because that's the definition of a thread entry function, same as the main program entry function main( ... ).

Is there a non kernel function for creating and using thread by the way ?

sceKernelCreateThread is actually a user function. Just because it starts with sceKernel doesn't mean the function only works in kernel mode.
See the header files in pspsdk\src\user

Yes your right about the main function :) forgot about that, for the PSP I always just pass void to the main function.

I yes I should have found that in the header files, I just assumed without checking if there is kernel in the name it is a kernel function :s will not do that anymore :D

[TyRaNiD]

The reason it needs to be static is due to C++ calling conventions. There are some tricks you can do to fudge it but normally best to do something akin to:

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class MyClass
{
public:
    static int ThreadEntry(int args, void *argp) {
         MyClass *this = *((MyClass **) argp;

         this->RunLoadingScreen();
         return 0;
    }
}

MyClass* p = new MyClass;
uid = sceKernelCreateThread("MyClassThread", MyClass::ThreadEntry, ...);
sceKernelStartThread(uid, sizeof(p), &p);

[pspZorba]

Does it mean that the real signature of a thread entry is :

int threadEntry( int argc, void *argv[] )

rather than

int threadEntry( int argc, void *argv )

[pspZorba]

froget about the question.

I understood my mistake