Kernel library crate for xous
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xous-kernel/src/uart.rs

66 lines
1.7 KiB

use core::fmt::{Error, Write};
pub struct Uart {}
impl Uart {
pub fn new() -> Uart {
Uart {}
}
pub fn putc(&self, c: u8) {
let ptr = 0xE000_1800 as *mut u32;
unsafe {
while ptr.add(1).read_volatile() == 0 {}
ptr.add(0).write_volatile(c as u32);
}
}
fn get(&self, base_addr: usize) -> Option<u8> {
let ptr = 0xE000_1800 as *mut u32;
unsafe {
if ptr.add(2).read_volatile() == 0 {
Some(ptr.add(0).read_volatile() as u8)
} else {
None
}
}
}
}
// This is a slightly different syntax. Write is this "trait", meaning it is much like
// an interface where we're just guaranteeing a certain function signature. In the Write
// trait, one is absolutely required to be implemented, which is write_str. There are other
// functions, but they all rely on write_str(), so their default implementation is OK for now.
impl Write for Uart {
// The trait Write expects us to write the function write_str
// which looks like:
fn write_str(&mut self, s: &str) -> Result<(), Error> {
for c in s.bytes() {
self.putc(c);
}
// Return that we succeeded.
Ok(())
}
}
#[macro_export]
macro_rules! print
{
($($args:tt)+) => ({
use core::fmt::Write;
let _ = write!(crate::uart::Uart::new(), $($args)+);
});
}
#[macro_export]
macro_rules! println
{
() => ({
print!("\r\n")
});
($fmt:expr) => ({
print!(concat!($fmt, "\r\n"))
});
($fmt:expr, $($args:tt)+) => ({
print!(concat!($fmt, "\r\n"), $($args)+)
});
}