blob: a9aa52137c5b47e60dff255dd048dfc275017aa7 [file] [log] [blame]
#include "descriptor_tables.h"
#include "vga.h"
#include "io.h"
#include "pic.h"
extern void gdt_flush(uint gdt);
extern void idt_flush(uint idt);
static void gdt_set_gate(uint i, uint base, uint limit, uchar access, uchar gran);
static void idt_set_gate(uchar num, uint base, ushort selector, uchar flags);
struct gdt_entry gdt_entries[5];
struct gdt_pointer gdt_pointer;
struct idt_entry idt_entries[256];
struct idt_pointer idt_pointer;
static void (*isrs[32])() = {
isr0, isr1, isr2, isr3, isr4, isr5, isr6, isr7, isr8, isr9, isr10,
isr11, isr12, isr13, isr14, isr15, isr16, isr17, isr18, isr19, isr20, isr21,
isr22, isr23, isr24, isr25, isr26, isr27, isr28, isr29, isr30, isr31};
static void (*irqs[16])() = {irq0, irq1, irq2, irq3, irq4, irq5,
irq6, irq7, irq8, irq9, irq10, irq11,
irq12, irq13, irq14, irq15};
void init_gdt()
{
vga_write("Initializing GDT...\n");
gdt_pointer.limit = sizeof(struct gdt_entry) * 5 - 1;
gdt_pointer.base = (uint)&gdt_entries;
gdt_set_gate(0, 0, 0, 0, 0); // Null segment
gdt_set_gate(1, 0, ~0, 0x9a, 0xcf); // Code segment
gdt_set_gate(2, 0, ~0, 0x92, 0xcf); // Data segment
gdt_set_gate(3, 0, ~0, 0xfa, 0xcf); // User mode code segment
gdt_set_gate(4, 0, ~0, 0xf2, 0xcf); // User mode data segment
for (volatile uint i = 0; i < 0x1000; i++)
{} // waste some time, for some reason this helps
gdt_flush((uint) &gdt_pointer);
vga_write("GDT Initialized\n");
}
static void gdt_set_gate(uint i, uint base, uint limit, uchar access, uchar gran)
{
struct gdt_entry *e = &gdt_entries[i];
e->base_low = base & 0xffff;
e->base_middle = (base >> 16) & 0xff;
e->base_high = (base >> 24) & 0xff;
e->limit_low = limit & 0xffff;
e->granularity = ((limit >> 16) & 0x0f) | (gran & 0xf0);
e->access = access;
}
void init_idt()
{
idt_pointer.limit = sizeof(struct idt_entry) * 256 - 1;
idt_pointer.base = (uint)&idt_entries;
memset(&idt_entries, 0, sizeof(idt_entries));
vga_write("sizeof(idt_entries) = ");
vga_putx(sizeof(idt_entries));
vga_put('\n');
vga_write("isr0 = ");
vga_putx((uint)isrs[0]);
vga_put('\n');
for (int i = 0; i < 32; i++)
{
idt_set_gate(i, (uint)isrs[i], 0x08, 0x8e);
}
idt_flush((uint)&idt_pointer);
// Remap PIC
outb(PIC1_COMMAND, 0x11);
outb(PIC2_COMMAND, 0x11);
outb(PIC1_DATA, 0x20);
outb(PIC2_DATA, 0x28);
outb(PIC1_DATA, 0x04);
outb(PIC2_DATA, 0x02);
outb(PIC1_DATA, 0x01);
outb(PIC2_DATA, 0x01);
outb(PIC1_DATA, 0);
outb(PIC2_DATA, 0);
for (int i = 0; i < 16; i++)
{
idt_set_gate(i + 32, (uint)irqs[i], 0x08, 0x8e);
}
vga_write("IDT Initialized!\n");
}
static void idt_set_gate(uchar num, uint base, ushort selector, uchar flags)
{
struct idt_entry *e = &idt_entries[num];
e->base_low = base & 0xffff;
e->base_high = (base >> 16) & 0xffff;
e->selector = selector;
e->zero = 0;
e->flags = flags /* | 0x60 */;
}
void init_descriptor_tables()
{
init_gdt();
init_idt();
}