Supervisor mode

src/time.rs

@@ -0,0 +1,66 @@
+use core::time::Duration;
+
+use alloc::format;
+
+use crate::{
+    set_csr,
+    vga::{Color, Vga, FONT_WIDTH, WIDTH},
+};
+
+pub const IRQ_M_TIMER: u8 = 1 << 7;
+pub const IRQ_S_TIMER: u8 = 1 << 5;
+const CLINT_TIMER_CMP: *mut u64 = 0x02004000 as *mut u64;
+const CLINT_TIMER: *const u64 = 0x0200bff8 as *const u64;
+const TIMER_FREQUENCY: u64 = 10000000; // 10MHz
+const INTERRUPT_FREQUENCY: u64 = 20; // 20Hz
+
+static mut START_TIME: Instant = Instant(0);
+
+pub fn setup_timer_interrupt() {
+    unsafe { START_TIME = Instant::now() };
+    set_csr!(sie, IRQ_S_TIMER);
+    setup_next_timer_interrupt();
+}
+
+pub fn setup_next_timer_interrupt() {
+    unsafe {
+        core::ptr::write_volatile(
+            CLINT_TIMER_CMP,
+            Instant::now().0 + TIMER_FREQUENCY / INTERRUPT_FREQUENCY,
+        );
+    }
+}
+pub fn timer_interrupt() {
+    let current_time = elapsed_time_since_startup();
+    let seconds = current_time.as_secs();
+    let minutes = seconds / 60 % 60;
+    let hours = seconds / 3600 % 60;
+    let seconds = seconds % 60;
+    let formated_time = format!("{:02}:{:02}:{:02}", hours, minutes, seconds);
+    unsafe {
+        Vga::draw_string(
+            (WIDTH - formated_time.len() * FONT_WIDTH) as u16,
+            0,
+            formated_time,
+            Color::WHITE,
+            Color::BLACK,
+        )
+    };
+}
+
+pub fn elapsed_time_since_startup() -> Duration {
+    unsafe { START_TIME.elapsed() }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Instant(u64);
+
+impl Instant {
+    pub fn now() -> Self {
+        Instant(unsafe { core::ptr::read_volatile(CLINT_TIMER) })
+    }
+    pub fn elapsed(&self) -> Duration {
+        let now = Self::now();
+        Duration::from_nanos((now.0 - self.0) * (1_000_000_000 / TIMER_FREQUENCY))
+    }
+}