1 files changed, 61 insertions, 0 deletions
diff --git a/src/idt.h b/src/idt.h
new file mode 100644
index 0000000..3aa5a1e
--- /dev/null
+++ b/src/idt.h
@@ -0,0 +1,61 @@
+#pragma once
+
+#include <types.h>
+
+class IDT {
+public:
+  struct Pointer {
+    uint16_t limit;
+    uint32_t base;
+  } __attribute__((packed));
+
+  enum InterruptType : uint8_t {
+    Null = 0,
+    InterruptGate = 0b110,  // hardware interrupts are disabled while the handler runs
+    TrapGate = 0b111,       // hardware interrupts remain active while the handler runs
+    TaskGate = 0b101,       // selector points to TSS rather than a code segment
+  };
+
+  class Entry {
+  public:
+    Entry(uint32_t offset = 0, uint16_t select = 0, InterruptType t = Null) {
+      offset_0_15 = offset & 0xffff;
+      offset_16_31 = (offset & 0xffff0000) >> 16;
+      selector = select;
+      type = t;
+    }
+
+  private:
+    uint16_t offset_0_15;                //  0-15 offset in the segment
+    uint16_t selector;                   // 16-31 selector of the code segment
+    [[maybe_unused]] uint8_t null = 0;   // 32-39 unused in protected mode
+    InterruptType type : 3;              // 40-42 type
+    [[maybe_unused]] bool d : 1 = true;  //    43 true: 32-bit, false: 16-bit segment
+    [[maybe_unused]] uint8_t u : 1 = 0;  //    44 unused
+    uint8_t dpl : 2 = 0;                 // 45-46 descriptor privilege level
+    [[maybe_unused]] bool e : 1 = true;  //    47 enable
+    uint16_t offset_16_31;               // 48-63 offset high
+  } __attribute__((packed));
+
+  IDT();
+
+private:
+  Entry table[256];
+};
+
+struct interrupt_frame {
+  uword_t ip;
+  uword_t cs;
+  uword_t flags;
+  uword_t sp;
+  uword_t ss;
+};
+
+/* https://wiki.osdev.org/Interrupt_Service_Routines */
+template <uint8_t irq>
+__attribute__((interrupt)) void kirq(interrupt_frame* frame);
+
+template <>
+void kirq<0x0>(interrupt_frame* frame);
+template <>
+void kirq<0x1>(interrupt_frame* frame);