Passing the address of a function to a function.

[SqueezyPeas]

Hi

I'm new to C and I'm trying to modify some existing code to use command line parameters in place of global constants. I've coded and debugged the parameter passing but I'm struggling to modify the existing code to accept parameters to some functions.

This line...

wiringPiISR (Parameters.GPIO_A, INT_EDGE_BOTH, &encoderPulse(Parameters));

generates the following warning and error:

NewIQ_rot.c:286:49: warning: taking address of expression of type 'void'
wiringPiISR (Parameters.GPIO_A, INT_EDGE_BOTH, &encoderPulse(Parameters));
^
NewIQ_rot.c:286:49: error: lvalue required as unary '&' operand

The carat symbol aligns with the &.

Parameters is the data structure that contains the command line parameters. The encoderPulse function used to be just encoderPulse() but I want to pass it the data structure. wiringPiISR is from an external library found here...

WiringPi

I'm confused and would be grateful for any help.

[Satya]

Is it possible to show the code

[SqueezyPeas]

Is it possible to show the code

Hi Satya.

The function is:

void encoderPulse(struct paramList Encoder)
{


        if ( inCriticalSection == TRUE ) return;
        inCriticalSection = TRUE;


        int MSB = digitalRead(Encoder.GPIO_A);
        int LSB = digitalRead(Encoder.GPIO_B);


        int encoded = (MSB << 1) | LSB;
        int sum = (lastEncoded << 2) | encoded;


        if(sum == 0b1101 || sum == 0b0100 || sum == 0b0010 || sum == 0b1011) encoderPos++;
        else if(sum == 0b1110 || sum == 0b0111 || sum == 0b0001 || sum == 0b1000) encoderPos--;


        lastEncoded = encoded;
        inCriticalSection = FALSE;
}

The entire code is here ... NewIQ_rot.c. It is very much work in progress. Thanks.