Abusing the stack pointer for fun and profit

StackManipulation.c

/*
 * StackManipulation.c
 *
 * Created: 27/04/2013 2:34:22 PM
 *  Author: MrTrick
 */ 


#include <avr/io.h>
#include <avr/interrupt.h>
#include <inttypes.h>

uint8_t depth = 8;

void cancel() {
  SP = RAMEND; //Completely clear the stack
  cli();
  run(); //Run never returns
}

void funcx() {
  if (--depth==0) {
    depth = 8;
    cancel();
  }
  funcx();
}

void run(void) {
  while(1)
  {
    //Some pointless assignations to occupy the controller
    PORTC = 0xF0;
    PORTB = 0x0F;
	
    //This function just takes too long... so it'll be cancelled 
    //after a few recursions, and execution will restart at the top of runMain()
    funcx();
  }
}


int main(void)
{
    //init stuff...
    //

    run();
}