PIC18 xc8 compiler : how to resolve warning (335) unknown pragma "code"

Question

I'm trying to compile this code to blink led with button interrupt, using xc8 compiler and PIC18F4550. I got those warning, so the code lines are ignored and the program doesn't work properly (by clinking on button nothing happens)

newmain.c:45: warning: (335) unknown pragma "code"
newmain.c:46: warning: (335) unknown pragma "interrupt"
newmain.c:65: warning: (335) unknown pragma "code"

program code

#define _XTAL_FREQ 4000000
#include <pic18f4550.h>

// BEGIN CONFIG
#pragma config OSC = HS

static int cpt = 1;

void IntExternal_INT(void) {
    TRISB0 = 1; // PORT B0 as input
    INT0E = 1;
    INTCONbits.PEIE = 1; //enable periphyrical interrupts 
    INTCONbits.GIE = 1;
    INTEDG0 = 0; //: Interrupt Edge Select bit : 1 = Interrupt on rising edge of RB0/INT pin
    //  0 = interrupt on falling edge
    INT0F = 0;
}

void delay() {
    volatile int i, j;
    for (i = 0; i < 2000; i++)
        for (j = 0; j < 10; j++);
}

#pragma code isr = 0x08 // Store the below code at address 0x08
#pragma interrupt isr  // let the compiler know that the function isr() is an interrupt handler

void iscr(void) {
    cpt++;

    if (INT0IF) //If External Edge INT Interrupt
    {
        LATDbits.LATD0 = 1; // RD-0 to High
        LATDbits.LATD1 = 1; // RD-1 to High
        delay();
        LATDbits.LATD0 = 0; // RD-0 to LOW
        LATDbits.LATD1 = 0; // RD-1 to LOW
        delay();
        INT0IF = 0; // clear the interrupt
    }
}    
#pragma code // Return to the default code section

void main(void) {
    IntExternal_INT();
    TRISD = 0xF0; // PORT B Setting: Set all the pins in port D to Output.
    while (1) {
        if (cpt % 2 == 0) {
            delay();
            LATDbits.LATD0 = 1; // RD-0 to High
            LATDbits.LATD1 = 1; // RD-1 to High
            delay();
            LATDbits.LATD0 = 0; // RD-0 to LOW
            LATDbits.LATD1 = 0; // RD-1 to LOW
        }
    }
}

Answer 1

Have you read the XC8 user's guide? Section 5.9 deals with interrupts.

In there it states:

The function qualifier interrupt (or __interrupt) can be applied to a C function definition so that it will be executed once the interrupt occurs. The compiler will process the interrupt function differently to any other functions, generating code to save and restore any registers used and return using a special instruction.

and:

An interrupt function must be declared as type void interrupt and cannot have parameters. This is the only function prototype that makes sense for an interrupt function since they are never directly called in the source code.

It then goes on to give an example:

int tick_count;

void interrupt tc_int(void)
{
    if (TMR0IE && TMR0IF) {
        TMR0IF=0;
        ++tick_count;
        return;
    }
    // process other interrupt sources here, if required
}

The compiler itself handles inserting the code into the right location in the vector table to call the ISR.

By default it uses the high priority interrupt vector. To specify the low priority vector instead, insert the attribute low_priority:

void interrupt low_priority tc_int()

Answer 2

In addition to Majenko's correct answer, you have other issues with your code. It looks like you lifted a configuration setting from an example you found somewhere. Unfortunately, the configuration settings on every PIC are different. The only exception to that is PICs within the same family. You cannot simply copy configuration settings from source code for a different PIC and hope it will work. As it is, your code will not work due to a lack of proper configuration settings.

Luckily, getting the correct configuration settings is very easy. Assuming you're using MPLAB X, go to Windows->PIC Memory Views->Configuration Bits. A new tab called "Configuration Bits" should open at the bottom of the screen. Adjust the settings as you need under the Options column (hint: you will want to turn the WDT off and the FOSC to HS, everything else can probably stay the same). Then click the "Generate Source Code to Output" button. It will produce a long list of "#pragma config" lines. Copy everything and paste it at the top of your code.