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86 lines
2.1 KiB
Rust

//! Implement the Qemu magic UART.
use core::fmt;
use crate::traits::console::{Console, Write};
use crate::traits::synchronization::{DummyMutex, Mutex};
/// The address for the magic qemu output
const QEMU_MAGIC_OUTPUT_ADDR: *mut u8 = 0x3F20_1000 as *mut u8;
/// The unique qemu output allowing access to the qemu output.
static QEMU_OUTPUT: QemuOutput = QemuOutput::new();
/// A structure allowing access to the qemu magic output.
struct QemuOutput {
inner: DummyMutex<QemuOutputInner>,
}
/// Inner Qemu output.
struct QemuOutputInner;
impl QemuOutputInner {
/// Constructor for [`QemuOutputInner`].
const fn new() -> Self {
Self {}
}
/// Write a character to the output.
fn write_char(&mut self, c: char) {
unsafe {
core::ptr::write_volatile(QEMU_MAGIC_OUTPUT_ADDR, c as u8);
}
}
}
impl QemuOutput {
/// Constructor for [`QemuOutput`].
pub const fn new() -> Self {
Self {
inner: DummyMutex::new(QemuOutputInner::new()),
}
}
}
/// Allow to use QemuOutputInner for print! and formating macros.
/// `write_str` needs `&mut self` (mutable ref), so we can implement
/// it only on the inner type, the `QemuOutput` need to be manipulable
/// using unmutable references (`&self`), so we will use a custom
/// interface for it.
impl fmt::Write for QemuOutputInner {
fn write_str(&mut self, s: &str) -> fmt::Result {
for c in s.chars() {
// \n -> \r\n
if c == '\n' {
self.write_char('\r');
}
self.write_char(c);
}
Ok(())
}
}
impl Write for QemuOutput {
fn write_char(&self, c: char) {
self.inner.lock(|q_out| q_out.write_char(c))
}
fn write_fmt(&self, args: fmt::Arguments) -> fmt::Result {
self.inner.lock(|q_out| fmt::Write::write_fmt(q_out, args))
}
/// Empty function, the qemu uart has no buffering afaik
fn flush(&self) {
// self.inner.lock(|q_out| q_out.flush())
}
}
impl Console for QemuOutput {}
// TODO: move?
/// Return a reference to the Qemu Output.
pub fn console() -> &'static dyn Console {
&QEMU_OUTPUT
}