*** ERROR L107: ADDRESS SPACE OVERFLOW

int key_board()
{
	int a = 0,b = 0,c = 0,d = 0,e = 0,f = 0,g = 0,h = 0;
	int port = 0,r2 = 0,r3 = 0,r4 = 0,r5 = 0,r6 = 0;
	LED_R = 0;
	port = KEY_PORT;
	a = port & 0x03;
	if(a == 0)					// SJMP no Key
	{				
		return key = 0;
	}
    
	// Waite:	
	while (b != 0)				// 
	{
		entprell();
		port = KEY_PORT;
		b = port & 0x03;
	}
	 
//START_ZYKLUS:
	r4 = 0xFE;
	r1 = 0x00;
	r2 = PORT_ANZ;

//Ribbon_1:
	while (r2 != 0) {
	
	r5 = 0x01;
	r3 = PORT_ANZ;
	c = KEY_PORT;
	c = c | KEY_INIT;		// bitwise OR
	c = c & r4;
	KEY_PORT = c;
	
//Ribbon_2:
	while (r3 != 0) {				//
		
		d = r2;
		d = d ^ r3;							// ^ exclusive OR
		
		if(d == 0) {			// DIAGO
			f = r5;
			f <<= 1;			// Shift bit to the left
			r5 = f;
			r3 = r3 -1;
			
		}

		e = KEY_PORT;
		e = e & r5;
		
		
		if (e == 0) {		// --> TAZU
			entprell();
			h = KEY_PORT;
			h = h & r5;
			if ( h != 0) {
				return key = 0;
			}
			if ( h == 0) {
				return key = 1;
			}
		}
		r1 = r1 +1;
			f = r5;
			f <<= 1;			// Shift bit to the left
			r5 = f;
			r3 = r3 -1;
			
	
	}	// End while(r3 !=0)
		
    g = r4;
    g <<= 1;			// Shift bit to the left
    r4 = g;
    r2 = r2 -1;
}	// End while(r2 !=0)		
	
	return key = 0;
}