timer.rs

#![feature(no_std, lang_items, start, core_intrinsics, asm)]
#![crate_type = "staticlib"]
#![no_std]

const GPIO_BASE: u32 = 0x20200000;
const TIMER_BASE: u32 = 0x20003000;
const LED_GPFSEL: isize = 4;
const LED_GPFBIT: isize = 21;
const LED_GPSET: isize = 8;
const LED_GPCLR: isize  = 11;
const LED_GPIO_BIT: isize = 15;

#[no_mangle]
pub fn main() {
    let gpio = GPIO_BASE as *const u32;

    let counter_lo = (TIMER_BASE + 0x4) as *mut u32;

    loop {

        let ts = unsafe { *(counter_lo) as u32 };

        while (unsafe { *(counter_lo) as u32 } - ts) < 500000 {
            unsafe { asm!("") }
        }

        unsafe {
            *(gpio.offset(LED_GPCLR) as *mut _) = 1 << LED_GPIO_BIT;
        }

        let ts = unsafe { *(counter_lo) as u32 };

        while (unsafe { *(counter_lo) as u32 } - ts) < 500000 {
            unsafe { asm!("") }
        }

        unsafe {
            *(gpio.offset(LED_GPSET) as *mut _) = 1 << LED_GPIO_BIT;
        }
    }
}

#[lang = "rust_begin_unwind"] extern fn rust_begin_unwind() {}
#[lang = "eh_personality"] extern fn eh_personality() {}
#[lang = "panic_fmt"] extern fn panic_fmt() -> ! { loop {} }
#[no_mangle]
pub unsafe fn __aeabi_unwind_cpp_pr0() -> () {
    loop {}
}