Visual C++ Function Address

[InsightSoft]

Hi,

I have this problem:

1--- the declaration

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void *irq_routines[16];

2--- the values

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void _cls_irq::InstallHandler(int irq, void (*handler)(tpRegistersStructure *)) 
{
	 irq_routines[irq] = (void *)handler;
}

and

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void handler_Timer(tpRegistersStructure *r)
{
    blablabla
}

then

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IRQ.InstallHandler(0, handler_Timer);            //get handler_timer function address and put on irq_routines[0]

3----- the problem (for every irq)

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void handler_IRQ(tpRegistersStructure *r)
{
    void (*handler)(tpRegistersStructure *r);            //pointer for incoming function with this format -> return (void *) and 
                                                                                       //get (tpRegistersStructure *r) as parameters
    
      handler = irq_routines[(r->int_no - 32)];       //with this index, get its correspondent function address

      (this does not run!!!!!!!!!!!!!!!!!! -> Can you tel me why???

this simple example just works fine:

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void (*p)(int i); 
p = myfunction;  
(*p)(23); // call myfunction with 23 as parameter

[ JamesM: Added code tags. ]

[pcmattman]

Firstly, please use code tags - they make it far easier to read your post!

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handler = irq_routines[(r->int_no - 32)]; //with this index, get its correspondent function address

Do you actually ever call the function?

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handler(r);

[InsightSoft]

Yap...

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void handler_IRQ(tpRegistersStructure *r)
{
    void (*handler)(tpRegistersStructure *r);
	handler = irq_routines[(r->int_no - 32)];						//to discover in matrix that start from 0 index
    if(handler)
    {
        handler(r);												//execute this address
    }
    if(r->int_no >= 40)
    {
		Ports.SendByte(0xA0, 0x20);
    }
    Ports.SendByte(0x20, 0x20);
}

[InsightSoft]

The result is:

error C2440: '=' : cannot convert from 'void *' to 'void (__cdecl *)(tpRegistersStructure *)'

[pcmattman]

Okay, that's because you've defined irq_handlers as:

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void *irq_routines[16];

Yet you want to use it as a:

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void (*handler)(tpRegistersStructure *)

You either need to use a cast when obtaining the IRQ handler from the array, or you need to typedef the handler function pointer type and use that instead of void*.

[JamesM]

Hi,

Firstly, you didn't mention if the IRQ handler gets called at all - you only mentioned the IRQ dispatch afterwards. Does the function IRQ_Handler get called when an IRQ comes in?

If not, which is what I suspect, have you remapped the PIC? Have you enabled interrupts?

Cheers,

James

[InsightSoft]

Yap...
...remember: that error is at compilation stage...

[pcmattman]

And I told you how to fix the compilation error. Read my post for the answer

[InsightSoft]

Ya... I know... its what I am trying to do

[InsightSoft]

Okay, that's because you've defined irq_handlers as:

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void *irq_routines[16];

Yet you want to use it as a:

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void (*handler)(tpRegistersStructure *)

You either need to use a cast when obtaining the IRQ handler from the array, or you need to typedef the handler function pointer type and use that instead of void*.

And how to do that? can you help me?

[Creature]

Gah.. Please know your function pointers before you use them:

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typedef void (*FunctionPointerType)(tpRegistersStructure *);

FunctionPointerType ArrayOfFunctionPointers[16];

Now you (should) have an array of function pointers which point to a function with 'void' as return type and 1 argument, namely a 'tpRegistersStructure' pointer.

[JamesM]

Know your language!

[DeletedAccount]

Hi,
This a a general 'C' question and has nothing to do with VC++ compiler . Bad topic


Regards
Shrek