1 files changed, 46 insertions, 0 deletions
diff --git a/arch/i686/lidt.c b/arch/i686/lidt.c
new file mode 100644
index 0000000..efbade3
--- /dev/null
+++ b/arch/i686/lidt.c
@@ -0,0 +1,46 @@
+#include <idt.h>
+#include <stdint.h>
+
+struct __attribute__((packed)) Pointer {
+  uint16_t limit;
+  uint32_t base;
+};
+
+enum Type {
+  Null = 0,
+  Intr = 0b10001110, // 32-bit interrupt
+};
+
+struct __attribute__((packed)) Gate_t {
+  uint16_t offset_15_0;  // segment offset low
+  uint16_t selector;     // code segment selector
+  uint8_t __unused;      // unused in protected mode
+  uint8_t type;          // interrupt type
+  uint16_t offset_31_16; // segment offset high
+};
+_Static_assert(sizeof(struct Gate_t) == 8);
+
+void
+Gate(struct Gate_t *entry, void *f, uint16_t selector)
+{
+  uint32_t f_addr = (uint32_t)f;
+  entry->offset_15_0 = f_addr & 0xffff;
+  entry->offset_31_16 = (f_addr >> 16) & 0xffff;
+  entry->selector = selector;
+  entry->__unused = 0;
+  entry->type = Intr;
+}
+
+static struct Gate_t interrupt_table[256] __attribute((aligned(4096)));
+
+void
+idt_install()
+{
+  for (int i = 0; i <= 0x2f; ++i) Gate(&interrupt_table[i], &interrupt_handler, 0x10);
+  Gate(&interrupt_table[0x80], &abort_handler, 0x10);
+
+  const struct Pointer ptr = {.limit = sizeof(interrupt_table) - 1, .base = (unsigned)&interrupt_table};
+  asm volatile("lidt (%0)" : : "a"(&ptr));
+
+  asm volatile("sti");
+}