From 46fb7adb706bd92c04ea1d578a167cf5dd3f0f16 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Sun, 15 Sep 2019 12:52:02 +0200
Subject: Added interrupt service routines and interrupt requests

---
 src/interrupts/idt.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 src/interrupts/idt.c

(limited to 'src/interrupts/idt.c')

diff --git a/src/interrupts/idt.c b/src/interrupts/idt.c
new file mode 100644
index 0000000..641de3a
--- /dev/null
+++ b/src/interrupts/idt.c
@@ -0,0 +1,47 @@
+#include "../memory/memory.h"
+
+struct idt_entry {
+    unsigned short base_lo;
+    unsigned short sel; // Kernel segment
+    unsigned char always0; // Always 0
+    unsigned char flags;
+    unsigned short base_hi;
+} __attribute__((packed));
+
+struct idt_ptr {
+    unsigned short limit;
+    unsigned int base;
+} __attribute__((packed));
+
+// Initialize IDT with 256 entries
+struct idt_entry idt[256];
+struct idt_ptr idtp;
+
+// Defined in boot.asm
+extern void idt_load();
+
+void idt_set_gate(unsigned char num, unsigned long base, unsigned short sel, unsigned char flags) {
+    // Specify the interrupt routine's base address
+    idt[num].base_lo = (base & 0xFFFF);
+    idt[num].base_hi = (base >> 16) & 0xFFFF;
+
+    // Set selector/segment of IDT entry
+    idt[num].sel = sel;
+    idt[num].always0 = 0;
+    idt[num].flags = flags;
+}
+
+
+// Install IDT
+void idt_install() {
+    // Set IDT pointer and limit
+    idtp.limit = (sizeof(struct idt_entry) * 256) - 1;
+    idtp.base = &idt;
+
+    // Clear IDT by setting memory cells to 0
+    memory_set(&idt, 0, sizeof(struct idt_entry) * 256);
+
+    // TODO: Add method to add ISRs to IDT
+
+    idt_load();
+}
-- 
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