/*----------------------------------------------------------------------------*/
#define GPIO_BASE 0x20200000
#define GPIO_FSEL 0x00
#define GPIO_FSET 0x07
#define GPIO_FCLR 0x0A
#define GPIO_FGET 0x0D
//*----------------------------------------------------------------------------*/
#define MY_LED 47
#define MY_SWITCH 3
/*----------------------------------------------------------------------------*/
/** using macros :p */
#define gpio_output(x) gpio[GPIO_FSEL+(x/10)]=1<<(x%10)*3
#define gpio_clr(x) gpio[GPIO_FCLR+(x/32)]=1<<(x%32)
#define gpio_set(x) gpio[GPIO_FSET+(x/32)]=1<<(x%32)
#define gpio_get(x) (gpio[GPIO_FGET+(x/32)]&(1<<(x%32)))
/*----------------------------------------------------------------------------*/
volatile unsigned int *gpio;
/*----------------------------------------------------------------------------*/
void main(void)
{
	/** base register address */
	gpio = (unsigned int*) GPIO_BASE;
	/** configure gpio as output, by default it is an input pin */
	gpio_output(MY_LED);
	/** main loop */
	while(1)
	{
		if(gpio_get(MY_SWITCH)) gpio_set(MY_LED);
		else gpio_clr(MY_LED);
	}
}
/*----------------------------------------------------------------------------*/