Blink led on raspberry pi 9 (Rust lang)

gpio.rs

#![feature(core_intrinsics)]
#[warn(dead_code)]
//#[warn(unused_assignments)]

extern crate mmap;
extern crate libc;
use libc::*;
use std::ffi::CString;
use std::path::Path;
use mmap::{MemoryMap,MapOption};
use std::os::unix::io::AsRawFd;
use std::fs::OpenOptions;
use std::intrinsics::offset;
use std::thread;

const BCM2708_PERI_BASE: usize = 0x20000000;
const GPIO_BASE: usize = BCM2708_PERI_BASE + 0x200000; /* GPIO controller */
const PAGE_SIZE: usize = 4*1024;
const BLOCK_SIZE: usize = 4*1024;


macro_rules! inp_gpio {
    ($gpio:expr, $pin:expr) => {
        unsafe {
            let out_pin = $pin;
            let p = std::intrinsics::offset($gpio.data() as *const u32, out_pin/10) as *mut u32;
            println!("{:b}", *p);
            *p &= !(7 << ( (out_pin % 10) * 3 ));
            println!("{:b}", *p);
        }
    }
}

macro_rules! out_gpio {
    ($gpio:expr, $pin:expr) => {
        unsafe {
            let out_pin = $pin;
            let p = std::intrinsics::offset($gpio.data() as *const u32, out_pin/10) as *mut u32;
            println!("{:b}", *p);
            *p |= 1 << ( (out_pin % 10) * 3 );
            println!("{:b}", *p);
        }
    }
}

fn main() {
    let gpio;

    /* Map GPIO ports into memory */

    {
        //let path = &b"/dev/mem"[..];
        //let path = CString::new(path).unwrap();
        let mem = OpenOptions::new().read(true).write(true).open("/dev/mem").unwrap();
        let mem_fd = mem.as_raw_fd();
        //let mem_fd = unsafe {
        //    libc::open(path.as_ptr(), libc::O_RDWR | libc::O_SYNC, 0o666)
        //};
        gpio = MemoryMap::new(4*1024, &[
                MapOption::MapReadable,
                MapOption::MapWritable,
                MapOption::MapFd(mem_fd),
                MapOption::MapOffset(GPIO_BASE),
                MapOption::MapNonStandardFlags(libc::MAP_SHARED)
            ]).unwrap();

    }

    /* Set pin 17 as output */

    inp_gpio!(gpio, 17);
    out_gpio!(gpio, 17);

    /* Set pin 17 to high */

    unsafe {
        let gpio_set = std::intrinsics::offset(gpio.data() as *const u32, 7) as *mut u32;
        *gpio_set = 1<<17;
        println!("{:b}", *gpio_set);
    }

    thread::sleep_ms(4000);

    unsafe {
        let gpio_clr = std::intrinsics::offset(gpio.data() as *const u32, 10) as *mut u32;
        *gpio_clr = 1<<17;
        println!("{:b}", *gpio_clr);
    }

    thread::sleep_ms(4000);

    println!("end.");
}