Print test results over serial port

src/main.rs

@@ -6,6 +6,7 @@
 
 use core::panic::PanicInfo;
 
+mod serial;
 mod vga_buffer;
 
 #[no_mangle]
@@ -20,7 +21,7 @@ pub extern "C" fn _start() -> ! {
 
 #[cfg(test)]
 fn test_runner(tests: &[&dyn Fn()]) {
-    println!("Running {} tests", tests.len());
+    serial_println!("Running {} tests", tests.len());
     for test in tests {
         test();
     }
@@ -50,7 +51,7 @@ pub unsafe fn exit_qemu(exit_code: QemuExitCode) {
 
 #[test_case]
 fn trivial_assertion() {
-    print!("trivial assertion... ");
+    serial_print!("trivial assertion... ");
     assert_eq!(1, 1);
-    println!("[ok]");
+    serial_println!("[ok]");
 }

src/serial.rs

@@ -0,0 +1,37 @@
+use lazy_static::lazy_static;
+use spin::Mutex;
+use uart_16550::SerialPort;
+
+lazy_static! {
+    pub static ref SERIAL1: Mutex<SerialPort> = {
+        let mut serial_port = unsafe { SerialPort::new(0x3F8) };
+        serial_port.init();
+        Mutex::new(serial_port)
+    };
+}
+
+#[doc(hidden)]
+pub fn _print(args: ::core::fmt::Arguments) {
+    use core::fmt::Write;
+    SERIAL1
+        .lock()
+        .write_fmt(args)
+        .expect("Printing to serial failed");
+}
+
+/// Prints to the host through the serial interface.
+#[macro_export]
+macro_rules! serial_print {
+    ($($arg:tt)*) => {
+        $crate::serial::_print(format_args!($($arg)*));
+    };
+}
+
+/// Prints to the host through the serial interface, appending a newline.
+#[macro_export]
+macro_rules! serial_println {
+    () => ($crate::serial_print!("\n"));
+    ($fmt:expr) => ($crate::serial_print!(concat!($fmt, "\n")));
+    ($fmt:expr, $($arg:tt)*) => ($crate::serial_print!(
+        concat!($fmt, "\n"), $($arg)*));
+}