#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>

#define HW_REGS_BASE ( 0xff200000 )
#define HW_REGS_SPAN ( 0x00200000 )
#define HW_REGS_MASK ( HW_REGS_SPAN - 1 )
#define LED_PIO_BASE 0x00
#define HEX3_HEX0_OFFSET 0x20

int main(void)
{
    volatile unsigned int *h2p_lw_led_addr=NULL;
	void *virtual_base;
	int fd;
     volatile int i;
    
    // Open /dev/mem
	if( ( fd = open( "/dev/mem", ( O_RDWR | O_SYNC ) ) ) == -1 ) {
		printf( "ERROR: could not open \"/dev/mem\"...\n" );
		return( 1 );
	}
    
    // get virtual addr that maps to physical
	virtual_base = mmap( NULL, HW_REGS_SPAN, ( PROT_READ | PROT_WRITE ), MAP_SHARED, fd, HW_REGS_BASE );	
	if( virtual_base == MAP_FAILED ) {
		printf( "ERROR: mmap() failed...\n" );
		close( fd );
		return(1);
	}
    
    // Get the address that maps to the LEDs
	h2p_lw_led_addr=(unsigned int *)(virtual_base + (( LED_PIO_BASE ) & ( HW_REGS_MASK ) ));
    
	while(1){
    	// Add 1 to the PIO register
    		*h2p_lw_led_addr = *h2p_lw_led_addr + 1;
	}

	if( munmap( virtual_base, HW_REGS_SPAN ) != 0 ) {
		printf( "ERROR: munmap() failed...\n" );
		close( fd );
		return( 1 );

	}
	close( fd );
	return 0;
}