From 6f0a745adc1ee021d2f366edc758443ee56cf948 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Tue, 13 Feb 2018 14:27:26 +0100
Subject: [PATCH] Ability to bind handler functions to interrupts

---
 src/kernel/boot/kmain.c         | 12 +++++++++++-
 src/kernel/cpu/interrupts.c     | 15 +++++++++++++--
 src/kernel/include/interrupts.h |  4 ++++
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/kernel/boot/kmain.c b/src/kernel/boot/kmain.c
index 13f9d1a..025dc2c 100644
--- a/src/kernel/boot/kmain.c
+++ b/src/kernel/boot/kmain.c
@@ -4,6 +4,14 @@
 #include <debug.h>
 #include <multiboot.h>
 #include <cpu.h>
+#include <interrupts.h>
+
+registers *divbyzero(registers *r)
+{
+  debug_error("Divide by zero error!\n");
+  debug_print_registers(r);
+  for(;;);
+}
 
 void kmain(uint64_t multiboot_magic, void *multiboot_data)
 {
@@ -17,8 +25,10 @@ void kmain(uint64_t multiboot_magic, void *multiboot_data)
 
   cpu_init();
 
-  // Force a divide by zero exception
+
+  // Force and catch a divide by zero exception
   // ISR 0
+  bind_interrupt(0, divbyzero);
   int a = 5, b = 0;
   int c = a/b;
 
diff --git a/src/kernel/cpu/interrupts.c b/src/kernel/cpu/interrupts.c
index c82814d..d159a70 100644
--- a/src/kernel/cpu/interrupts.c
+++ b/src/kernel/cpu/interrupts.c
@@ -5,9 +5,10 @@
 
 struct int_gate_descriptor idt[NUM_INTERRUPTS];
 struct idtr idtr;
-
 extern uintptr_t isr_table[];
 
+int_handler_t int_handlers[NUM_INTERRUPTS];
+
 void idt_set_gate(uint32_t num, uintptr_t vector, uint16_t cs, uint8_t ist, uint8_t flags)
 {
   idt[num].base_l = vector & 0xFFFF;
@@ -21,6 +22,7 @@ void idt_set_gate(uint32_t num, uintptr_t vector, uint16_t cs, uint8_t ist, uint
 void interrupt_init()
 {
   memset(idt, 0, sizeof(idt));
+  memset(int_handlers, 0, sizeof(int_handlers));
 
   for(int i=0; i < NUM_INTERRUPTS; i++)
   {
@@ -32,9 +34,18 @@ void interrupt_init()
   load_idt(&idtr);
 }
 
+int_handler_t bind_interrupt(uint32_t num, int_handler_t fn)
+{
+  int_handler_t old = int_handlers[num];
+  int_handlers[num] = fn;
+  return old;
+}
+
 registers *int_handler(registers *r)
 {
-  (void)r;
+  if(int_handlers[r->int_no])
+    return int_handlers[r->int_no](r);
+
   debug("Unhandled interrupt occurred\n");
   debug("Interrupt number: %d Error code: %d\n", r->int_no, r->err_code);
   debug_print_registers(r);
diff --git a/src/kernel/include/interrupts.h b/src/kernel/include/interrupts.h
index 3bbbdab..01ab576 100644
--- a/src/kernel/include/interrupts.h
+++ b/src/kernel/include/interrupts.h
@@ -63,4 +63,8 @@ debug("CS=%016x SS=%016x\n", r->cs, r->ss); \
 debug("CR0=%08x CR2=%016x CR3=%016x CR4=%08x\n", read_cr0(), read_cr2(), read_cr3(), read_cr4());
 
 
+typedef registers *(*int_handler_t)(registers *);
+
 void interrupt_init();
+int_handler_t bind_interrupt(uint32_t num, int_handler_t fn);
+void isr_return(registers *);