Add ns16550a

os/src/fs/stdio.rs

@@ -1,10 +1,8 @@
 use super::File;
+use crate::drivers::chardev::{CharDevice, UART};
 use crate::mm::UserBuffer;
-use crate::sbi::console_getchar;
-use crate::task::suspend_current_and_run_next;
 
 pub struct Stdin;
-
 pub struct Stdout;
 
 impl File for Stdin {
@@ -16,18 +14,7 @@ impl File for Stdin {
     }
     fn read(&self, mut user_buf: UserBuffer) -> usize {
         assert_eq!(user_buf.len(), 1);
-        // busy loop
-        let mut c: usize;
-        loop {
-            c = console_getchar();
-            if c == 0 {
-                suspend_current_and_run_next();
-                continue;
-            } else {
-                break;
-            }
-        }
-        let ch = c as u8;
+        let ch = UART.read();
         unsafe {
             user_buf.buffers[0].as_mut_ptr().write_volatile(ch);
         }