isr.c

// Implementation for Interrupt Service Routines
// http://wiki.osdev.org/Interrupt_Service_Routines

#include "isr.h"
#include "idt.h"
#include "ports.h"
#include "timer.h"
#include "../drivers/keyboard.h"
#include "../drivers/screen.h"
#include "../libc/mem.h"
#include "../libc/string.h"

isr_t interrupt_handlers[256];

// Array of messages when some exception is occured
// Its indexes are mapped to interrupt codes
char *exception_messages[] = {
  "Division By Zero",
  "Debug",
  "Non Maskable Interrupt",
  "Breakpoint",
  "Into Detected Overflow",
  "Out of Bounds",
  "Invalid Opcode",
  "No Coprocessor",

  "Double Fault",
  "Coprocessor Segment Overrun",
  "Bad TSS",
  "Segment Not Present",
  "Stack Fault",
  "General Protection Fault",
  "Page Fault",
  "Unknown Interrupt",

  "Coprocessor Fault",
  "Alignment Check",
  "Machine Check",
  "Reserved",
  "Reserved",
  "Reserved",
  "Reserved",
  "Reserved",

  "Reserved",
  "Reserved",
  "Reserved",
  "Reserved",
  "Reserved",
  "Reserved",
  "Reserved",
  "Reserved"
};

// Maps ISR in interrupt.asm to gates in IDT
void isr_install() {
  set_idt_gate(0, (uint32_t)isr0);
  set_idt_gate(1, (uint32_t)isr1);
  set_idt_gate(2, (uint32_t)isr2);
  set_idt_gate(3, (uint32_t)isr3);
  set_idt_gate(4, (uint32_t)isr4);
  set_idt_gate(5, (uint32_t)isr5);
  set_idt_gate(6, (uint32_t)isr6);
  set_idt_gate(7, (uint32_t)isr7);
  set_idt_gate(8, (uint32_t)isr8);
  set_idt_gate(9, (uint32_t)isr9);
  set_idt_gate(10, (uint32_t)isr10);
  set_idt_gate(11, (uint32_t)isr11);
  set_idt_gate(12, (uint32_t)isr12);
  set_idt_gate(13, (uint32_t)isr13);
  set_idt_gate(14, (uint32_t)isr14);
  set_idt_gate(15, (uint32_t)isr15);
  set_idt_gate(16, (uint32_t)isr16);
  set_idt_gate(17, (uint32_t)isr17);
  set_idt_gate(18, (uint32_t)isr18);
  set_idt_gate(19, (uint32_t)isr19);
  set_idt_gate(20, (uint32_t)isr20);
  set_idt_gate(21, (uint32_t)isr21);
  set_idt_gate(22, (uint32_t)isr22);
  set_idt_gate(23, (uint32_t)isr23);
  set_idt_gate(24, (uint32_t)isr24);
  set_idt_gate(25, (uint32_t)isr25);
  set_idt_gate(26, (uint32_t)isr26);
  set_idt_gate(27, (uint32_t)isr27);
  set_idt_gate(28, (uint32_t)isr28);
  set_idt_gate(29, (uint32_t)isr29);
  set_idt_gate(30, (uint32_t)isr30);
  set_idt_gate(31, (uint32_t)isr31);

  // Remap the PIC
  // http://wiki.osdev.org/8259_PIC#Initialisation
  port_byte_out(0x20, 0x11);
  port_byte_out(0xA0, 0x11);
  port_byte_out(0x21, 0x20);
  port_byte_out(0xA1, 0x28);
  port_byte_out(0x21, 0x04);
  port_byte_out(0xA1, 0x02);
  port_byte_out(0x21, 0x01);
  port_byte_out(0xA1, 0x01);
  port_byte_out(0x21, 0x0);
  port_byte_out(0xA1, 0x0);

  // Install IRQs into our IDT
  set_idt_gate(32, (uint32_t)irq0);
  set_idt_gate(33, (uint32_t)irq1);
  set_idt_gate(34, (uint32_t)irq2);
  set_idt_gate(35, (uint32_t)irq3);
  set_idt_gate(36, (uint32_t)irq4);
  set_idt_gate(37, (uint32_t)irq5);
  set_idt_gate(38, (uint32_t)irq6);
  set_idt_gate(39, (uint32_t)irq7);
  set_idt_gate(40, (uint32_t)irq8);
  set_idt_gate(41, (uint32_t)irq9);
  set_idt_gate(42, (uint32_t)irq10);
  set_idt_gate(43, (uint32_t)irq11);
  set_idt_gate(44, (uint32_t)irq12);
  set_idt_gate(45, (uint32_t)irq13);
  set_idt_gate(46, (uint32_t)irq14);
  set_idt_gate(47, (uint32_t)irq15);

  set_idt();
}

// Calls every time when some interrupt is occured
// This function is available in interrupt.asm file via extern in asm
void isr_handler(registers_t r) {
  char s[3];

  print("Received interrupt: ");
  itoa(r.int_no, s);
  print(s);
  print("\n");
  print(exception_messages[r.int_no]);
  print("\n");
}

void irq_install() {
  __asm__ __volatile__("sti");

  init_timer(50);
  init_keyboard();
}

// Calls every time when hardware interrupt is occured
void irq_handler(registers_t r) {
  if (r.int_no >= 40) {
    port_byte_out(0xA0, 0x20);
  }

  port_byte_out(0x20, 0x20);

  if (interrupt_handlers[r.int_no] != 0) {
    isr_t handler = interrupt_handlers[r.int_no];
    handler(r);
  }
}

void register_interrupt_handler(uint8_t n, isr_t handler) {
  interrupt_handlers[n] = handler;
}