feat(libkos): add print!/println! macros via debug_putchar

crates/libkos/src/io.rs

@@ -0,0 +1,28 @@
+use core::fmt;
+
+struct Writer;
+
+impl fmt::Write for Writer {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for &b in s.as_bytes() {
+            crate::syscall::debug_putchar(b);
+        }
+        Ok(())
+    }
+}
+
+pub fn _print(args: fmt::Arguments) {
+    use fmt::Write;
+    Writer.write_fmt(args).ok();
+}
+
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => ($crate::io::_print(format_args!($($arg)*)));
+}
+
+#[macro_export]
+macro_rules! println {
+    () => ($crate::print!("\n"));
+    ($($arg:tt)*) => ($crate::print!("{}\n", format_args!($($arg)*)));
+}

crates/libkos/src/lib.rs

@@ -5,6 +5,7 @@ extern crate alloc;
 mod arch;
 pub mod syscall;
 pub mod alloc_impl;
+pub mod io;
 mod rt;
 
 #[cfg(target_os = "none")]