add timer interrupt

Cargo.lock

@@ -41,10 +41,20 @@ version = "0.1.0"
 dependencies = [
  "bootloader",
  "lazy_static",
+ "pic8259",
  "spin 0.5.2",
  "uart_16550",
  "volatile 0.2.7",
- "x86_64",
+ "x86_64 0.14.13",
+]
+
+[[package]]
+name = "pic8259"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "62d9a86c292b165f757e47e7fd66855def189b2564609bc4203727b27c33db22"
+dependencies = [
+ "x86_64 0.15.2",
 ]
 
 [[package]]
@@ -73,7 +83,7 @@ checksum = "614ff2a87880d4bd4374722268598a970bbad05ced8bf630439417347254ab2e"
 dependencies = [
  "bitflags 1.3.2",
  "rustversion",
- "x86_64",
+ "x86_64 0.14.13",
 ]
 
 [[package]]
@@ -99,3 +109,15 @@ dependencies = [
  "rustversion",
  "volatile 0.4.6",
 ]
+
+[[package]]
+name = "x86_64"
+version = "0.15.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0f042214de98141e9c8706e8192b73f56494087cc55ebec28ce10f26c5c364ae"
+dependencies = [
+ "bit_field",
+ "bitflags 2.9.0",
+ "rustversion",
+ "volatile 0.4.6",
+]

Cargo.toml

@@ -9,6 +9,7 @@ volatile = "0.2.6"
 spin = "0.5.2"
 x86_64 = "0.14.2"
 uart_16550 = "0.2.0"
+pic8259 = "0.11.0"
 
 [dependencies.lazy_static]
 version = "1.0"

src/interrupts.rs

@@ -1,7 +1,8 @@
 use lazy_static::lazy_static;
+use pic8259::ChainedPics;
 use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
 
-use crate::{gdt, println};
+use crate::{gdt, print, println};
 
 lazy_static! {
     static ref IDT: InterruptDescriptorTable = {
@@ -12,6 +13,7 @@ lazy_static! {
                 .set_handler_fn(double_fault_handler)
                 .set_stack_index(gdt::DOUBLE_FAULT_IST_INDEX);
         }
+        idt[InterruptIndex::Timer.as_usize()].set_handler_fn(timer_interrupt_handler);
 
         idt
     };
@@ -32,6 +34,37 @@ extern "x86-interrupt" fn double_fault_handler(
     panic!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
 }
 
+pub const PIC_1_OFFSET: u8 = 32;
+pub const PIC_2_OFFSET: u8 = PIC_1_OFFSET + 8;
+
+pub static PICS: spin::Mutex<ChainedPics> =
+    spin::Mutex::new(unsafe { ChainedPics::new(PIC_1_OFFSET, PIC_2_OFFSET) });
+
+#[derive(Debug, Clone, Copy)]
+#[repr(u8)]
+pub enum InterruptIndex {
+    Timer = PIC_1_OFFSET,
+}
+
+impl InterruptIndex {
+    fn as_u8(self) -> u8 {
+        self as u8
+    }
+
+    fn as_usize(self) -> usize {
+        usize::from(self.as_u8())
+    }
+}
+
+extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: InterruptStackFrame) {
+    print!(".");
+
+    unsafe {
+        PICS.lock()
+            .notify_end_of_interrupt(InterruptIndex::Timer.as_u8());
+    }
+}
+
 #[test_case]
 fn test_breakpoint_exception() {
     x86_64::instructions::interrupts::int3();

src/lib.rs

@@ -39,7 +39,7 @@ pub fn test_panic_handler(info: &PanicInfo) -> ! {
     serial_println!("[failed]\n");
     serial_println!("Error: {}\n", info);
     exit_qemu(QemuExitCode::Failed);
-    loop {}
+    hlt_loop();
 }
 
 #[cfg(test)]
@@ -47,7 +47,7 @@ pub fn test_panic_handler(info: &PanicInfo) -> ! {
 pub extern "C" fn _start() -> ! {
     init();
     test_main();
-    loop {}
+    hlt_loop();
 }
 
 #[cfg(test)]
@@ -72,7 +72,17 @@ pub fn exit_qemu(exit_code: QemuExitCode) {
     }
 }
 
+pub fn hlt_loop() -> ! {
+    loop {
+        x86_64::instructions::hlt();
+    }
+}
+
 pub fn init() {
     gdt::init();
     interrupts::init_idt();
+    unsafe {
+        interrupts::PICS.lock().initialize();
+    }
+    x86_64::instructions::interrupts::enable();
 }

src/main.rs

@@ -11,7 +11,7 @@ use nel_os::println;
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
     println!("{}", info);
-    loop {}
+    nel_os::hlt_loop();
 }
 
 #[cfg(test)]
@@ -29,5 +29,5 @@ pub extern "C" fn _start() -> ! {
     #[cfg(test)]
     test_main();
 
-    loop {}
+    nel_os::hlt_loop();
 }

src/serial.rs

@@ -13,10 +13,14 @@ lazy_static! {
 #[doc(hidden)]
 pub fn _print(args: ::core::fmt::Arguments) {
     use core::fmt::Write;
-    SERIAL1
-        .lock()
-        .write_fmt(args)
-        .expect("Printing to serial failed");
+    use x86_64::instructions::interrupts;
+
+    interrupts::without_interrupts(|| {
+        SERIAL1
+            .lock()
+            .write_fmt(args)
+            .expect("Printing to serial failed");
+    });
 }
 
 #[macro_export]

src/vga_buffer.rs

@@ -26,7 +26,11 @@ macro_rules! println {
 #[doc(hidden)]
 pub fn _print(args: fmt::Arguments) {
     use core::fmt::Write;
-    WRITER.lock().write_fmt(args).unwrap();
+    use x86_64::instructions::interrupts;
+
+    interrupts::without_interrupts(|| {
+        WRITER.lock().write_fmt(args).unwrap();
+    });
 }
 
 #[allow(dead_code)]
@@ -157,10 +161,16 @@ fn test_println_many() {
 
 #[test_case]
 fn test_println_output() {
+    use core::fmt::Write;
+    use x86_64::instructions::interrupts;
+
     let s = "Some test string that fits on a single line";
-    println!("{}", s);
-    for (i, c) in s.chars().enumerate() {
-        let screen_char = WRITER.lock().buffer.chars[BUFFER_HEIGHT - 2][i].read();
-        assert_eq!(char::from(screen_char.ascii_character), c);
-    }
+    interrupts::without_interrupts(|| {
+        let mut writer = WRITER.lock();
+        writeln!(writer, "\n{}", s).expect("writeln failed");
+        for (i, c) in s.chars().enumerate() {
+            let screen_char = writer.buffer.chars[BUFFER_HEIGHT - 2][i].read();
+            assert_eq!(char::from(screen_char.ascii_character), c);
+        }
+    });
 }