feat(input-server): add InputServer<D: InputDevice> with protocol, mock + UART adapters, and tests

crates/servers/input-server/src/adapters/qemu_uart.rs

@@ -0,0 +1,48 @@
+use crate::input_device::InputDevice;
+use crate::protocol::{InputEvent, Key};
+
+const UART_BASE: usize = 0x10000000;
+const UART_LSR: usize = 5;
+
+pub struct UartInputDevice {
+    base: usize,
+}
+
+impl UartInputDevice {
+    pub fn new() -> Self {
+        Self { base: UART_BASE }
+    }
+
+    fn read_byte(&self) -> Option<u8> {
+        let lsr = unsafe { core::ptr::read_volatile((self.base + UART_LSR) as *const u8) };
+        if lsr & 1 != 0 {
+            Some(unsafe { core::ptr::read_volatile(self.base as *const u8) })
+        } else {
+            None
+        }
+    }
+
+    fn byte_to_key(byte: u8) -> Key {
+        match byte {
+            b'w' | b'W' => Key::Up,
+            b's' | b'S' => Key::Down,
+            b'a' | b'A' => Key::Left,
+            b'd' | b'D' => Key::Right,
+            b'\r' | b'\n' => Key::Enter,
+            0x1B => Key::Escape,
+            c => Key::Char(c),
+        }
+    }
+}
+
+impl InputDevice for UartInputDevice {
+    fn poll(&mut self) -> Option<InputEvent> {
+        let byte = self.read_byte()?;
+        Some(InputEvent::KeyDown(Self::byte_to_key(byte)))
+    }
+
+    fn has_event(&self) -> bool {
+        let lsr = unsafe { core::ptr::read_volatile((self.base + UART_LSR) as *const u8) };
+        lsr & 1 != 0
+    }
+}