Add first C user program

src/kernel/idt.c

@@ -0,0 +1,40 @@
+#include "src/kernel/idt.h"
+
+struct idt_entry {
+  uint16_t offset_low;
+  uint16_t selector;
+  uint8_t ist;
+  uint8_t flags;
+  uint16_t offset_mid;
+  uint32_t offset_high;
+  uint32_t zero;
+} __attribute__((packed));
+
+struct idt_descriptor {
+  uint16_t size;
+  uint64_t offset;
+} __attribute__((packed));
+
+static struct idt_entry idt[256];
+static struct idt_descriptor idt_desc;
+
+static void idt_load() {
+  idt_desc.size = sizeof(idt) - 1;
+  idt_desc.offset = (uint64_t)&idt;
+  __asm__ volatile("lidt %0" : : "m"(idt_desc));
+}
+
+inline void idt_init() {
+  idt_load();
+}
+
+void idt_set_entry(int vector, void (*handler)(struct interrupt_frame *), uint8_t flags) {
+  uint64_t addr = (uint64_t)handler;
+  idt[vector].offset_low = addr & 0xFFFF;
+  idt[vector].selector = 0x0010;
+  idt[vector].ist = 0;
+  idt[vector].flags = flags;
+  idt[vector].offset_mid = (addr >> 16) & 0xFFFF;
+  idt[vector].offset_high = (addr >> 32) & 0xFFFFFFFF;
+  idt[vector].zero = 0;
+}