C/C++ Setvect question

[su817200]

Hi friend,
I got error in the following line while compiling ->

void PC_VectSet (INT8U vect, void (*isr)(void))
{
setvect(vect, (void interrupt (*)(void))isr); /* Error in this line*/
}

error C2059: syntax error : ')'

Someone please help

Rgds,

[Banfa]

What compiler are you using?
Is interrupt an extension keyword for that compiler?

Assuming interrupt is a keyword casting to change the function type in that manor may well not work, often the compiler has to generate different code for an interrupt routine so the function needs to be declared with the interrupt keyword.

[donbock]

Presumably you added the cast because the following didn't work.

setvect(vect, isr);

.

Presumably the prototype for setvect is

void setvect(INT8U vector, void interrupt (*isr)(void));

I don't use function pointers very often, but in the cast you might try moving the function name into the parentheses with the asterisk (*).

This shouldn't really make a difference, but why don't you try using an intermediate function pointer variable:

void interrupt (*myisr)(void) = isr;
setvect(vector, myisr);

If necessary you can try casting tricks on the function pointer line without an enclosing function call to muddy the waters.

[weaknessforcats]

You declare a function pointer by making a copy of the function prototype:

int MyFunction(int a, int b);

Then replace the function name with a pair of parentheses that have and * and the name of your pointer inside:

int (*ptr)(int a, int b);

Then then you can assign the address of MyFubnction to your pointer:

ptr = MyFunction;

Then when you:

int answer = ptr(3,4);

you have called MyFunction.

Note that only a function with two int arguments that returns an int can be assigne to the pointer.

NEVER cast a function pointer unless you kjnow exactly what you are doing otherwise you have messed up the argument list and return value and that can cause a crash.