async keyboard

Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "autocfg"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
+
 [[package]]
 name = "bit_field"
 version = "0.9.0"
@@ -20,6 +26,73 @@ version = "0.9.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7a3c1ceed1cd9e61c7998100cc18c13d413aa40d018992b871ab8e7435ce6372"
 
+[[package]]
+name = "cfg-if"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
+
+[[package]]
+name = "conquer-once"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96eb12fb69466716fbae9009d389e6a30830ae8975e170eff2d2cff579f9efa3"
+dependencies = [
+ "conquer-util",
+]
+
+[[package]]
+name = "conquer-util"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "654fb2472cc369d311c547103a1fa81d467bef370ae7a0680f65939895b1182a"
+
+[[package]]
+name = "crossbeam-queue"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "774ba60a54c213d409d5353bda12d49cd68d14e45036a285234c8d6f91f92570"
+dependencies = [
+ "cfg-if",
+ "crossbeam-utils",
+ "maybe-uninit",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3c7c73a2d1e9fc0886a08b93e98eb643461230d5f1925e4036204d5f2e261a8"
+dependencies = [
+ "autocfg",
+ "cfg-if",
+]
+
+[[package]]
+name = "futures-core"
+version = "0.3.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0402f765d8a89a26043b889b26ce3c4679d268fa6bb22cd7c6aad98340e179d1"
+
+[[package]]
+name = "futures-task"
+version = "0.3.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a16bef9fc1a4dddb5bee51c989e3fbba26569cbb0e31f5b303c184e3dd33dae"
+
+[[package]]
+name = "futures-util"
+version = "0.3.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "feb5c238d27e2bf94ffdfd27b2c29e3df4a68c4193bb6427384259e2bf191967"
+dependencies = [
+ "autocfg",
+ "futures-core",
+ "futures-task",
+ "pin-project-lite",
+ "pin-utils",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.4.0"
@@ -47,6 +120,12 @@ dependencies = [
  "scopeguard",
 ]
 
+[[package]]
+name = "maybe-uninit"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60302e4db3a61da70c0cb7991976248362f30319e88850c487b9b95bbf059e00"
+
 [[package]]
 name = "pc-keyboard"
 version = "0.5.1"
@@ -62,11 +141,26 @@ dependencies = [
  "x86_64",
 ]
 
+[[package]]
+name = "pin-project-lite"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d31d11c69a6b52a174b42bdc0c30e5e11670f90788b2c471c31c1d17d449443"
+
+[[package]]
+name = "pin-utils"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
+
 [[package]]
 name = "rust_os"
 version = "0.1.0"
 dependencies = [
  "bootloader",
+ "conquer-once",
+ "crossbeam-queue",
+ "futures-util",
  "lazy_static",
  "linked_list_allocator",
  "pc-keyboard",

Cargo.toml

@@ -13,6 +13,20 @@ pic8259 = "0.10.1"
 pc-keyboard = "0.5.0"
 linked_list_allocator = "0.9.0"
 
+[dependencies.crossbeam-queue]
+version = "0.2.1"
+default-features = false
+features = ["alloc"]
+
+[dependencies.futures-util]
+version = "0.3.4"
+default-features = false
+features = ["alloc"]
+
+[dependencies.conquer-once]
+version = "0.2.0"
+default-features = false
+
 [dependencies.lazy_static]
 version = "1.0"
 features = ["spin_no_std"]

src/interrupts.rs

@@ -66,31 +66,13 @@ extern "x86-interrupt" fn breakpoint_handler(
 }
 
 extern "x86-interrupt" fn keyboard_interrupt_handler(
-    _stack_frame: InterruptStackFrame)
-{
-    use pc_keyboard::{layouts, DecodedKey, HandleControl, Keyboard, ScancodeSet1};
-    use spin::Mutex;
+    _stack_frame: InterruptStackFrame
+) {
     use x86_64::instructions::port::Port;
 
-    lazy_static! {
-        static ref KEYBOARD: Mutex<Keyboard<layouts::Us104Key, ScancodeSet1>> =
-            Mutex::new(Keyboard::new(layouts::Us104Key, ScancodeSet1,
-                HandleControl::Ignore)
-            );
-    }
-
-    let mut keyboard = KEYBOARD.lock();
     let mut port = Port::new(0x60);
-
     let scancode: u8 = unsafe { port.read() };
-    if let Ok(Some(key_event)) = keyboard.add_byte(scancode) {
-        if let Some(key) = keyboard.process_keyevent(key_event) {
-            match key {
-                DecodedKey::Unicode(character) => print!("{}", character),
-                DecodedKey::RawKey(key) => print!("{:?}", key),
-            }
-        }
-    }
+    crate::task::keyboard::add_scancode(scancode);
 
     unsafe {
         PICS.lock()

src/main.rs

@@ -6,18 +6,17 @@
 
 extern crate alloc;
 
-use alloc::{boxed::Box, vec, vec::Vec, rc::Rc};
-use core::panic::PanicInfo;
 use rust_os::println;
-use rust_os::task::{Task, simple_executor::SimpleExecutor};
-use bootloader::{BootInfo, entry_point};
-use x86_64::VirtAddr;
+use rust_os::task::{executor::Executor, keyboard, Task};
+use bootloader::{entry_point, BootInfo};
+use core::panic::PanicInfo;
 
 entry_point!(kernel_main);
 
 fn kernel_main(boot_info: &'static BootInfo) -> ! {
     use rust_os::allocator;
     use rust_os::memory::{self, BootInfoFrameAllocator};
+    use x86_64::VirtAddr;
 
     println!("Hello World{}", "!");
     rust_os::init();
@@ -31,8 +30,9 @@ fn kernel_main(boot_info: &'static BootInfo) -> ! {
     allocator::init_heap(&mut mapper, &mut frame_allocator)
         .expect("heap initialization failed");
 
-    let mut executor = SimpleExecutor::new();
+    let mut executor = Executor::new();
     executor.spawn(Task::new(example_task()));
+    executor.spawn(Task::new(keyboard::print_keypresses())); 
     executor.run();
 
     #[cfg(test)]
@@ -42,15 +42,6 @@ fn kernel_main(boot_info: &'static BootInfo) -> ! {
     rust_os::hlt_loop();
 }
 
-async fn async_number() -> u32 {
-    42
-}
-
-async fn example_task() {
-    let number = async_number().await;
-    println!("async number: {}", number);
-}
-
 #[cfg(not(test))]
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
@@ -62,4 +53,13 @@ fn panic(info: &PanicInfo) -> ! {
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
     rust_os::test_panic_handler(info)
+}
+
+async fn async_number() -> u32 {
+    42
+}
+
+async fn example_task() {
+    let number = async_number().await;
+    println!("async number: {}", number);
 }

src/task/executor.rs

@@ -0,0 +1,104 @@
+use super::{Task, TaskId};
+use alloc::{collections::BTreeMap, sync::Arc};
+use core::task::Waker;
+use crossbeam_queue::ArrayQueue;
+use core::task::{Context, Poll};
+use alloc::task::Wake;
+
+pub struct Executor {
+    tasks: BTreeMap<TaskId, Task>,
+    task_queue: Arc<ArrayQueue<TaskId>>,
+    waker_cache: BTreeMap<TaskId, Waker>,
+}
+
+struct TaskWaker {
+    task_id: TaskId,
+    task_queue: Arc<ArrayQueue<TaskId>>,
+}
+
+impl Executor {
+    pub fn new() -> Self {
+        Executor {
+            tasks: BTreeMap::new(),
+            task_queue: Arc::new(ArrayQueue::new(100)),
+            waker_cache: BTreeMap::new(),
+        }
+    }
+
+    pub fn spawn(&mut self, task: Task) {
+        let task_id = task.id;
+        if self.tasks.insert(task.id, task).is_some() {
+            panic!("task with same ID already in tasks");
+        }
+        self.task_queue.push(task_id).expect("queue full");
+    }
+
+    fn run_ready_tasks(&mut self) {
+        // destructure `self` to avoid borrow checker errors
+        let Self {
+            tasks,
+            task_queue,
+            waker_cache,
+        } = self;
+
+        while let Ok(task_id) = task_queue.pop() {
+            let task = match tasks.get_mut(&task_id) {
+                Some(task) => task,
+                None => continue, // task no longer exists
+            };
+            let waker = waker_cache
+                .entry(task_id)
+                .or_insert_with(|| TaskWaker::new(task_id, task_queue.clone()));
+            let mut context = Context::from_waker(waker);
+            match task.poll(&mut context) {
+                Poll::Ready(()) => {
+                    // task done -> remove it and its cached waker
+                    tasks.remove(&task_id);
+                    waker_cache.remove(&task_id);
+                }
+                Poll::Pending => {}
+            }
+        }
+    }
+
+    pub fn run(&mut self) -> ! {
+        loop {
+            self.run_ready_tasks();
+            self.sleep_if_idle();
+        }
+    }
+
+    fn sleep_if_idle(&self) {
+        use x86_64::instructions::interrupts::{self, enable_and_hlt};
+
+        interrupts::disable();
+        if self.task_queue.is_empty() {
+            enable_and_hlt();
+        } else {
+            interrupts::enable();
+        }
+    }
+}
+
+impl TaskWaker {
+    fn wake_task(&self) {
+        self.task_queue.push(self.task_id).expect("task_queue full");
+    }
+
+    fn new(task_id: TaskId, task_queue: Arc<ArrayQueue<TaskId>>) -> Waker {
+        Waker::from(Arc::new(TaskWaker {
+            task_id,
+            task_queue,
+        }))
+    }
+}
+
+impl Wake for TaskWaker {
+    fn wake(self: Arc<Self>) {
+        self.wake_task();
+    }
+
+    fn wake_by_ref(self: &Arc<Self>) {
+        self.wake_task();
+    }
+}

src/task/keyboard.rs

@@ -0,0 +1,77 @@
+use conquer_once::spin::OnceCell;
+use crossbeam_queue::ArrayQueue;
+use crate::println;
+use core::{pin::Pin, task::{Poll, Context}};
+use futures_util::stream::Stream;
+use futures_util::task::AtomicWaker;
+use futures_util::stream::StreamExt;
+use pc_keyboard::{layouts, DecodedKey, HandleControl, Keyboard, ScancodeSet1};
+use crate::print;
+
+static WAKER: AtomicWaker = AtomicWaker::new();
+static SCANCODE_QUEUE: OnceCell<ArrayQueue<u8>> = OnceCell::uninit();
+
+pub async fn print_keypresses() {
+    let mut scancodes = ScancodeStream::new();
+    let mut keyboard = Keyboard::new(layouts::Us104Key, ScancodeSet1,
+        HandleControl::Ignore);
+
+    while let Some(scancode) = scancodes.next().await {
+        if let Ok(Some(key_event)) = keyboard.add_byte(scancode) {
+            if let Some(key) = keyboard.process_keyevent(key_event) {
+                match key {
+                    DecodedKey::Unicode(character) => print!("{}", character),
+                    DecodedKey::RawKey(key) => print!("{:?}", key),
+                }
+            }
+        }
+    }
+}
+
+pub(crate) fn add_scancode(scancode: u8) {
+    if let Ok(queue) = SCANCODE_QUEUE.try_get() {
+        if let Err(_) = queue.push(scancode) {
+            println!("WARNING: scancode queue full; dropping keyboard input");
+        } else {
+            WAKER.wake(); // new
+        }
+    } else {
+        println!("WARNING: scancode queue uninitialized");
+    }
+}
+
+pub struct ScancodeStream {
+    _private: (),
+}
+
+impl ScancodeStream {
+    pub fn new() -> Self {
+        SCANCODE_QUEUE.try_init_once(|| ArrayQueue::new(100))
+            .expect("ScancodeStream::new should only be called once");
+        ScancodeStream { _private: () }
+    }
+}
+
+impl Stream for ScancodeStream {
+    type Item = u8;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<u8>> {
+        let queue = SCANCODE_QUEUE
+            .try_get()
+            .expect("scancode queue not initialized");
+
+        // fast path
+        if let Ok(scancode) = queue.pop() {
+            return Poll::Ready(Some(scancode));
+        }
+
+        WAKER.register(&cx.waker());
+        match queue.pop() {
+            Ok(scancode) => {
+                WAKER.take();
+                Poll::Ready(Some(scancode))
+            }
+            Err(crossbeam_queue::PopError) => Poll::Pending,
+        }
+    }
+}

src/task/mod.rs

@@ -1,16 +1,21 @@
 use core::{future::Future, pin::Pin};
 use alloc::boxed::Box;
 use core::task::{Context, Poll};
+use core::sync::atomic::{AtomicU64, Ordering};
 
 pub mod simple_executor;
+pub mod keyboard;
+pub mod executor;
 
 pub struct Task {
+    id: TaskId,
     future: Pin<Box<dyn Future<Output = ()>>>,
 }
 
 impl Task {
     pub fn new(future: impl Future<Output = ()> + 'static) -> Task {
         Task {
+            id: TaskId::new(),
             future: Box::pin(future),
         }
     }
@@ -18,4 +23,14 @@ impl Task {
     fn poll(&mut self, context: &mut Context) -> Poll<()> {
         self.future.as_mut().poll(context)
     }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+struct TaskId(u64);
+
+impl TaskId {
+    fn new() -> Self {
+        static NEXT_ID: AtomicU64 = AtomicU64::new(0);
+        TaskId(NEXT_ID.fetch_add(1, Ordering::Relaxed))
+    }
 }