os/fs/
stdio.rs

1//!Stdin & Stdout
2use super::File;
3use crate::mm::UserBuffer;
4use crate::sbi::console_getchar;
5use crate::task::suspend_current_and_run_next;
6///Standard input
7pub struct Stdin;
8///Standard output
9pub struct Stdout;
10
11impl File for Stdin {
12    fn readable(&self) -> bool {
13        true
14    }
15    fn writable(&self) -> bool {
16        false
17    }
18    fn read(&self, mut user_buf: UserBuffer) -> usize {
19        assert_eq!(user_buf.len(), 1);
20        // busy loop
21        let mut c: usize;
22        loop {
23            c = console_getchar();
24            if c == 0 {
25                suspend_current_and_run_next();
26                continue;
27            } else {
28                break;
29            }
30        }
31        let ch = c as u8;
32        unsafe {
33            user_buf.buffers[0].as_mut_ptr().write_volatile(ch);
34        }
35        1
36    }
37    fn write(&self, _user_buf: UserBuffer) -> usize {
38        panic!("Cannot write to stdin!");
39    }
40}
41
42impl File for Stdout {
43    fn readable(&self) -> bool {
44        false
45    }
46    fn writable(&self) -> bool {
47        true
48    }
49    fn read(&self, _user_buf: UserBuffer) -> usize {
50        panic!("Cannot read from stdout!");
51    }
52    fn write(&self, user_buf: UserBuffer) -> usize {
53        for buffer in user_buf.buffers.iter() {
54            print!("{}", core::str::from_utf8(*buffer).unwrap());
55        }
56        user_buf.len()
57    }
58}
os/fs/stdio.rs

os/fs/
stdio.rs
