serial print macro

stage_3/build.rs

@@ -1,6 +1,6 @@
 fn main() {
-  const LINKER_SCRIPT_PATH: &str = "link.ld";
-  
-  println!("cargo::rerun-if-changed={}", LINKER_SCRIPT_PATH);
-  println!("cargo::rustc-link-arg=-T{}", LINKER_SCRIPT_PATH);
+    const LINKER_SCRIPT_PATH: &str = "link.ld";
+
+    println!("cargo::rerun-if-changed={}", LINKER_SCRIPT_PATH);
+    println!("cargo::rustc-link-arg=-T{}", LINKER_SCRIPT_PATH);
 }

stage_3/src/com.rs

@@ -1,6 +1,28 @@
 use core::{fmt, hint};
 
-use crate::ioport;
+use crate::{ioport, spin::Spinlock};
+
+const COM1_PORT: u16 = 0x3f8;
+
+pub static COM1: Spinlock<Option<Com>> = Spinlock::new(None);
+
+#[macro_export]
+macro_rules! com1_print {
+  ($($args:tt)*) => ({
+    crate::com::with_com1_if_available(|com1| {
+      ::core::write!(com1, $($args)*).ok();
+    });
+  })
+}
+
+#[macro_export]
+macro_rules! com1_println {
+  ($($args:tt)*) => ({
+    crate::com::with_com1_if_available(|com1| {
+      ::core::writeln!(com1, $($args)*).ok();
+    });
+  })
+}
 
 pub struct Com {
     port: u16,
@@ -8,10 +30,31 @@ pub struct Com {
 
 pub struct ComError;
 
+pub fn with_com1_if_available<F>(f: F)
+where
+    F: FnOnce(&mut Com),
+{
+    let mut guard = COM1.lock();
+    if let Some(com1) = guard.as_mut() {
+        f(com1);
+    }
+}
+
+pub unsafe fn try_com1_init() -> bool {
+    match unsafe { Com::init(COM1_PORT) } {
+        Ok(com1) => {
+            let mut guard = COM1.lock();
+            *guard = Some(com1);
+            true
+        }
+        _ => false,
+    }
+}
+
 impl Com {
     pub unsafe fn init(port: u16) -> Result<Self, ComError> {
         const ECHO_BYTE: u8 = 0x5a;
-        
+
         let echo = unsafe {
             // Unset DLAB
             ioport::outb(port + 3, 0x00);
@@ -43,9 +86,7 @@ impl Com {
             ioport::outb(port + 4, 0x0f);
         }
 
-        Ok(Self {
-            port,
-        })
+        Ok(Self { port })
     }
 
     pub fn poll_has_data(&self) -> bool {
@@ -74,19 +115,10 @@ impl Com {
 }
 
 impl fmt::Write for Com {
-  fn write_str(&mut self, s: &str) -> fmt::Result {
-    for b in s.bytes() {
-        self.write_poll(b);
-    }
-    Ok(())
-  }
-  
-  fn write_char(&mut self, c: char) -> fmt::Result {
-    let mut buf = [0u8; 4];
-    let s = c.encode_utf8(&mut buf);
-    for b in s.bytes() {
-        self.write_poll(b);
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for b in s.bytes() {
+            self.write_poll(b);
+        }
+        Ok(())
     }
-    Ok(())
-  }
 }

stage_3/src/ioport.rs

@@ -1,23 +1,23 @@
 use core::arch::asm;
 
 pub unsafe fn inb(port: u16) -> u8 {
-  let x: u8;
-  unsafe {
-    asm!(
-      "in al, dx",
-      in("dx") port,
-      lateout("al") x
-    );
-  }
-  x
+    let x: u8;
+    unsafe {
+        asm!(
+          "in al, dx",
+          in("dx") port,
+          lateout("al") x
+        );
+    }
+    x
 }
 
 pub unsafe fn outb(port: u16, x: u8) {
-  unsafe {
-    asm!(
-      "out dx, al",
-      in("al") x,
-      in("dx") port,
-    );
-  }
+    unsafe {
+        asm!(
+          "out dx, al",
+          in("al") x,
+          in("dx") port,
+        );
+    }
 }

stage_3/src/main.rs

@@ -3,54 +3,57 @@
 #![feature(custom_test_frameworks)]
 #![test_runner(crate::test_runner)]
 
-mod spin;
+mod com;
 mod ioport;
+mod spin;
 mod vga;
-mod com;
 
-use core::{arch::{asm, global_asm}, fmt::Write, panic::PanicInfo, ptr, slice};
+use core::{
+    arch::{asm, global_asm},
+    fmt::{self, Write},
+    panic::PanicInfo,
+    ptr, slice,
+};
 
 global_asm!(include_str!("asm/trampoline.s"));
 
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
-  vga_println!("panic!");
-  if let Some(location) = info.location() {
-    vga_println!("{}", location);
-  }
-  vga_println!("{}", info.message());
-  hlt()
+    vga_println!("panic!");
+    if let Some(location) = info.location() {
+        vga_println!("{}", location);
+    }
+    vga_println!("{}", info.message());
+    hlt()
 }
 
-const COM1_PORT: u16 = 0x3f8;
-
 #[unsafe(no_mangle)]
 pub extern "C" fn _start() -> ! {
-  vga::vga_init();
+    vga::vga_init();
 
-  let gdt_ptr = ptr::with_exposed_provenance::<u64>(0xc000);
-  let gdt_slice = unsafe { slice::from_raw_parts(gdt_ptr, 4) };
+    unsafe {
+        com::try_com1_init();
+    }
 
-  vga_println!("hello from rust :)");
-  vga_println!("{:016x}", gdt_slice[0]);
-  vga_println!("{:016x}", gdt_slice[1]);
-  vga_println!("{:016x}", gdt_slice[2]);
-  vga_println!("{:016x}", gdt_slice[3]);
-  
-  let mut com = unsafe { com::Com::init(COM1_PORT) };
+    let gdt_ptr = ptr::with_exposed_provenance::<u64>(0xc000);
+    let gdt_slice = unsafe { slice::from_raw_parts(gdt_ptr, 4) };
 
-  if let Ok(com) = &mut com {
-    writeln!(com, "hello serial").ok();
-  }
+    vga_println!("hello from rust :)");
+    vga_println!("{:016x}", gdt_slice[0]);
+    vga_println!("{:016x}", gdt_slice[1]);
+    vga_println!("{:016x}", gdt_slice[2]);
+    vga_println!("{:016x}", gdt_slice[3]);
 
-  hlt()
+    com1_println!("hello serial!");
+
+    hlt()
 }
 
 #[inline]
 fn hlt() -> ! {
-  loop {
-    unsafe {
-      asm!("hlt");
+    loop {
+        unsafe {
+            asm!("hlt");
+        }
     }
-  }
 }

stage_3/src/spin.rs

@@ -1,101 +1,104 @@
-use core::{cell::UnsafeCell, hint, ops::{Deref, DerefMut}, sync::atomic::{AtomicBool, Ordering}};
+use core::{
+    cell::UnsafeCell,
+    hint,
+    ops::{Deref, DerefMut},
+    sync::atomic::{AtomicBool, Ordering},
+};
 
 pub struct Spinlock<T> {
-  data: UnsafeCell<T>,
-  locked: AtomicBool,
+    data: UnsafeCell<T>,
+    locked: AtomicBool,
 }
 
 impl<T> Spinlock<T> {
-  pub const fn new(data: T) -> Self {
-    Self {
-      data: UnsafeCell::new(data),
-      locked: AtomicBool::new(false),
+    pub const fn new(data: T) -> Self {
+        Self {
+            data: UnsafeCell::new(data),
+            locked: AtomicBool::new(false),
+        }
     }
-  }
 
-  pub fn lock(&self) -> SpinlockGuard<'_, T> {
-    // If we observe `locked` was `false`, then:
-    // - Use acquire ordering, so nothing inside the critical section gets reordered before we
-    //   observed the `false` value.
-    // - Store `true`, so nothing else can enter the critical section until we exit it. 
-    // Otherwise, spin until we observe a `false` value.
-    while self.locked
-      .compare_exchange_weak(false, true, Ordering::Acquire, Ordering::Relaxed)
-      .is_err()
-    {
-      hint::spin_loop();
-    }
+    pub fn lock(&self) -> SpinlockGuard<'_, T> {
+        // If we observe `locked` was `false`, then:
+        // - Use acquire ordering, so nothing inside the critical section gets reordered before we
+        //   observed the `false` value.
+        // - Store `true`, so nothing else can enter the critical section until we exit it.
+        // Otherwise, spin until we observe a `false` value.
+        while self
+            .locked
+            .compare_exchange_weak(false, true, Ordering::Acquire, Ordering::Relaxed)
+            .is_err()
+        {
+            hint::spin_loop();
+        }
 
-    SpinlockGuard { lock: self }
-  }
+        SpinlockGuard { lock: self }
+    }
 
-  /// # Safety
-  /// There must be no "active" `SpinlockGuards` for this lock, i.e. a `SpinlockGuard` which can be
-  /// used to obtain a reference to the spinlock-protected data.
-  unsafe fn unlock(&self) {
-    // Unset `locked` with release ordering so that nothing inside the critical section gets
-    // reordered to after we stored `false`.
-    self.locked.store(false, Ordering::Release);
-  }
+    /// # Safety
+    /// There must be no "active" `SpinlockGuards` for this lock, i.e. a `SpinlockGuard` which can be
+    /// used to obtain a reference to the spinlock-protected data.
+    unsafe fn unlock(&self) {
+        // Unset `locked` with release ordering so that nothing inside the critical section gets
+        // reordered to after we stored `false`.
+        self.locked.store(false, Ordering::Release);
+    }
 
-  /// # Safety
-  /// No mutable references to the spinlock-protected data may exist.
-  unsafe fn get<'s, 'a>(&'s self) -> &'a T
-  where
-    's: 'a,
-  {
-    unsafe { &*self.data.get() }
-  }
+    /// # Safety
+    /// No mutable references to the spinlock-protected data may exist.
+    unsafe fn get<'s, 'a>(&'s self) -> &'a T
+    where
+        's: 'a,
+    {
+        unsafe { &*self.data.get() }
+    }
 
-  /// # Safety
-  /// No references to the spinlock-protected data may exist.
-  unsafe fn get_mut<'s, 'a>(&'s self) -> &'a mut T
-  where
-    's: 'a,
-  {
-    unsafe { &mut *self.data.get() }
-  }
+    /// # Safety
+    /// No references to the spinlock-protected data may exist.
+    unsafe fn get_mut<'s, 'a>(&'s self) -> &'a mut T
+    where
+        's: 'a,
+    {
+        unsafe { &mut *self.data.get() }
+    }
 }
 
-unsafe impl<T> Sync for Spinlock<T>
-where
-  T: Send,
-{}
+unsafe impl<T> Sync for Spinlock<T> where T: Send {}
 
 pub struct SpinlockGuard<'a, T> {
-  lock: &'a Spinlock<T>,
+    lock: &'a Spinlock<T>,
 }
 
 impl<'a, T> Deref for SpinlockGuard<'a, T> {
-  type Target = T;
+    type Target = T;
 
-  #[inline]
-  fn deref(&self) -> &Self::Target {
-    // SAFETY:
-    // For the entire lifetime of the `SpinlockGuard`, `locked` remains `true`, so we have
-    // exclusive access to `data`, so no mutable references to `data` can exist.
-    unsafe { self.lock.get() }
-  }
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        // SAFETY:
+        // For the entire lifetime of the `SpinlockGuard`, `locked` remains `true`, so we have
+        // exclusive access to `data`, so no mutable references to `data` can exist.
+        unsafe { self.lock.get() }
+    }
 }
 
 impl<'a, T> DerefMut for SpinlockGuard<'a, T> {
-  #[inline]
-  fn deref_mut(&mut self) -> &mut Self::Target {
-    // SAFETY:
-    // For the entire lifetime of the `SpinlockGuard`, `locked` remains `true`, so we have
-    // exclusive access to `data`, so no other references to `data` can exist.
-    unsafe { self.lock.get_mut() }
-  }
+    #[inline]
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        // SAFETY:
+        // For the entire lifetime of the `SpinlockGuard`, `locked` remains `true`, so we have
+        // exclusive access to `data`, so no other references to `data` can exist.
+        unsafe { self.lock.get_mut() }
+    }
 }
 
 impl<'a, T> Drop for SpinlockGuard<'a, T> {
-  fn drop(&mut self) {
-    // SAFETY:
-    // Only one `SpinlockGuard` can exist at a time for a particular lock, since we set `locked`
-    // to true before creating a guard and refuse to create any new ones until it is `false` again.
-    // Therefore, we are the only `SpinlockGuard` for the lock. Since this is the destructor, and
-    // we don't access the spinlock-protected data here, there are therefore no "active"
-    // `SpinlockGuard`s remaining for the lock.
-    unsafe { self.lock.unlock() }
-  }
+    fn drop(&mut self) {
+        // SAFETY:
+        // Only one `SpinlockGuard` can exist at a time for a particular lock, since we set `locked`
+        // to true before creating a guard and refuse to create any new ones until it is `false` again.
+        // Therefore, we are the only `SpinlockGuard` for the lock. Since this is the destructor, and
+        // we don't access the spinlock-protected data here, there are therefore no "active"
+        // `SpinlockGuard`s remaining for the lock.
+        unsafe { self.lock.unlock() }
+    }
 }

stage_3/src/vga.rs

@@ -29,101 +29,104 @@ macro_rules! vga_println {
 }
 
 pub fn vga_init() {
-  let vga_buf = unsafe { VgaBuf::new(ptr::with_exposed_provenance_mut::<u16>(VGA_ADDR)) };
-  let mut guard = VGA.lock();
-  *guard = Some(vga_buf);
+    let vga_buf = unsafe { VgaBuf::new(ptr::with_exposed_provenance_mut::<u16>(VGA_ADDR)) };
+    let mut guard = VGA.lock();
+    *guard = Some(vga_buf);
 }
 
 pub fn with_vga_buf<F>(f: F)
 where
-  F: FnOnce(&mut VgaBuf),
+    F: FnOnce(&mut VgaBuf),
 {
-  let mut guard = crate::vga::VGA.lock();
-  let vga = guard.as_mut().expect("vga not initialised");
-  f(vga);
+    let mut guard = VGA.lock();
+    let vga = guard.as_mut().expect("vga not initialised");
+    f(vga);
 }
 
 pub struct VgaBuf {
-  buf: *mut u16,
-  col: usize,
-  row: usize,
+    buf: *mut u16,
+    col: usize,
+    row: usize,
 }
 
 impl VgaBuf {
-  pub unsafe fn new(buf: *mut u16) -> Self {
-    Self { buf, col: 0, row: 0 }
-  }
+    pub unsafe fn new(buf: *mut u16) -> Self {
+        Self {
+            buf,
+            col: 0,
+            row: 0,
+        }
+    }
 
-  pub fn vga_write_str(&mut self, s: &str) {
-    for c in s.chars() {
-      self.vga_write_char(c);
+    pub fn vga_write_str(&mut self, s: &str) {
+        for c in s.chars() {
+            self.vga_write_char(c);
+        }
     }
-  }
 
-  pub fn vga_write_char(&mut self, c: char) {
-    let newline = c == '\n';
+    pub fn vga_write_char(&mut self, c: char) {
+        let newline = c == '\n';
 
-    if newline || self.col >= VGA_WIDTH {
-      self.col = 0;
-      self.row += 1;
-    }
+        if newline || self.col >= VGA_WIDTH {
+            self.col = 0;
+            self.row += 1;
+        }
 
-    if self.row >= VGA_HEIGHT {
-      self.scroll();
-      self.row -= 1;
-    }
+        if self.row >= VGA_HEIGHT {
+            self.scroll();
+            self.row -= 1;
+        }
 
-    if !newline {
-      self.vga_write_char_at(c, self.col, self.row);
-      self.col += 1;
+        if !newline {
+            self.vga_write_char_at(c, self.col, self.row);
+            self.col += 1;
+        }
     }
-  }
 
-  pub fn vga_write_ascii_char_at(&mut self, c: u8, col: usize, row: usize) {
-    let vga_val = COLOUR_MASK | u16::from(c);
+    pub fn vga_write_ascii_char_at(&mut self, c: u8, col: usize, row: usize) {
+        let vga_val = COLOUR_MASK | u16::from(c);
+
+        if col < VGA_WIDTH && row < VGA_HEIGHT {
+            unsafe {
+                self.coord_ptr(col, row).write_volatile(vga_val);
+            }
+        }
+    }
 
-    if col < VGA_WIDTH && row < VGA_HEIGHT {
-      unsafe {
-        self.coord_ptr(col, row)
-          .write_volatile(vga_val);
-      }
+    pub fn vga_write_char_at(&mut self, c: char, col: usize, row: usize) {
+        let c = u8::try_from(c).unwrap_or(0xfe);
+        self.vga_write_ascii_char_at(c, col, row);
     }
-  }
-
-  pub fn vga_write_char_at(&mut self, c: char, col: usize, row: usize) {
-    let c = u8::try_from(c).unwrap_or(0xfe);
-    self.vga_write_ascii_char_at(c, col, row);
-  }
-
-  fn scroll(&mut self) {
-    unsafe {
-      ptr::copy(
-        self.coord_ptr(0, 1),
-        self.coord_ptr(0, 0),
-        VGA_WIDTH * (VGA_HEIGHT - 1)
-      );
-      
-      for col in 0..VGA_WIDTH {
-        self.vga_write_ascii_char_at(0, col, VGA_HEIGHT - 1);
-      }
+
+    fn scroll(&mut self) {
+        unsafe {
+            ptr::copy(
+                self.coord_ptr(0, 1),
+                self.coord_ptr(0, 0),
+                VGA_WIDTH * (VGA_HEIGHT - 1),
+            );
+
+            for col in 0..VGA_WIDTH {
+                self.vga_write_ascii_char_at(0, col, VGA_HEIGHT - 1);
+            }
+        }
     }
-  }
 
-  unsafe fn coord_ptr(&self, col: usize, row: usize) -> *mut u16 {
-    unsafe { self.buf.add((row * VGA_WIDTH) + col) }
-  }
+    unsafe fn coord_ptr(&self, col: usize, row: usize) -> *mut u16 {
+        unsafe { self.buf.add((row * VGA_WIDTH) + col) }
+    }
 }
 
 impl fmt::Write for VgaBuf {
-  fn write_str(&mut self, s: &str) -> fmt::Result {
-    self.vga_write_str(s);
-    Ok(())
-  }
-  
-  fn write_char(&mut self, c: char) -> fmt::Result {
-    self.vga_write_char(c);
-    Ok(())
-  }
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.vga_write_str(s);
+        Ok(())
+    }
+
+    fn write_char(&mut self, c: char) -> fmt::Result {
+        self.vga_write_char(c);
+        Ok(())
+    }
 }
 
 unsafe impl Send for VgaBuf {}