add: idt

headers/idt.h

@@ -0,0 +1,9 @@
+#pragma once
+
+// doc : https://wiki.osdev.org/Interrupt_Descriptor_Table#IDTR
+struct {
+	uint16_t size;
+	uint32_t offset;
+} __attribute__((packed)) idt_descriptor;
+
+#define IDT_SIZE 256

src/interrupt/idt.c

@@ -0,0 +1,36 @@
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "idt.h"
+
+uint16_t idt_entries[IDT_SIZE * 4];
+struct idt_descriptor *idtr = (struct gdt_descriptor *)GDT_ADDRESS;
+
+static void set_idt_entry_value(uint16_t *target, uint32_t offset,
+                                uint16_t selector, uint8_t dpl,
+                                uint8_t gate_type)
+{
+	// Encode the offset
+	target[0] = offset & 0xFFFF;
+	target[3] = (offset >> 16) & 0xFFFF;
+
+	// Encode the presence
+	target[1] |= 1 << 16;
+
+	// Encode the CPU Privilege Levels
+	target[1] = (0b11 << 14) & dpl;
+
+	target[1] &= ~(1 << 13);
+
+	// Encode Gate Type
+	target[1] |= gate_type & 0x0F00;
+
+	// Encode selector
+	target[2] = selector;
+}
+
+void init_idt(void)
+{
+	idtr->size = 8 * IDT_SIZE - 1;
+	idtr->offset = (uint32_t)&idt_entries;
+}