MPLAB XC8 interrupt routine doesn't get called for IOC (pic 16f877a) simulator

Question

I have written some code, a simple program to try to increment a counter during an interrupt on portbbits.rb7 . The program builds without error however a warning exists that:

:: warning: (1273) Omniscient Code Generation not available in Free mode main.c:32: warning: (520) function "_Interrupt" is never called

#define _XTAL_FREQ 8000000

#include <pic16f887.h>
#include <xc.h>

char counter = 0;
char dummy = 0;

void main(void) 
{
    TRISB = 0x80;           //Configure PORTB pin 7 to input
    TRISC = 0xOO;           //Configure PORTC to output

    INTCONbits.RBIF = 0;    //clear interrupt on change flag 
    INTCONbits.GIE =  1;    //enable global interrupts
    INTCONbits.RBIE = 1;    //enable port change interrupt

    while(1)
     {
        PORTC = counter;    //update PORTC with value of counter
     }
     return;
}

void Interrupt (void)
{
    INTCONbits.RBIF = 0;  //clear Interrupt on change flag
    dummy = PORTB;        //do a dummy read to clear IOC flag
    counter++;            //increment counter
}

On the snippets of code I've seen, people are usually testing their interrupts on hardware. However I don't have the hardware as yet, so trying to do some simulations and checking out stuff in the address registers etc.

I made the assumption that I would be able verify the interrupt routine with just software (see attached screen grabs). File Registers Counter Variable Address

So if anyone can point out my omission, or lead me in the right direction, it would be much appreciated.

Answer 1

You need to add the function qualifier interrupt to the definition of your interrupt service routine, so the compile knows it's a interrupt service routine and not a regular function, and perhaps rename the function itself so the name and qualifier are clearly seperated:

void interrupt ISR (void) //Added 'interrupt' qualifier and renamed function to 'ISR' for clarity.
{
    INTCONbits.RBIF = 0;  //clear Interrupt on change flag
    dummy = PORTB;        //do a dummy read to clear IOC flag
    counter++;            //increment counter
}