Hello World on simulator

src/main.rs

@@ -0,0 +1,42 @@
+#![no_main]
+#![no_std]
+#![feature(asm_experimental_arch)]
+
+use core::{
+    arch::asm,
+    fmt::{self, Write},
+    panic::PanicInfo,
+};
+
+#[panic_handler]
+fn panic(_panic: &PanicInfo) -> ! {
+    loop {}
+}
+
+const UART0_DR: u32 = 0x3F20_1000;
+
+struct Uart;
+
+impl Write for Uart {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for byte in s.bytes() {
+            unsafe {
+                core::ptr::write_volatile(UART0_DR as *mut u8, byte);
+            }
+        }
+        Ok(())
+    }
+}
+
+#[no_mangle]
+#[unsafe(naked)]
+pub extern "C" fn _start() -> ! {
+    core::arch::naked_asm!("mov sp, #0x80000", "bl main");
+}
+
+#[no_mangle]
+fn main() {
+    let mut uart = Uart {};
+    writeln!(uart, "Hello World!\n");
+    loop {}
+}