#include <stdint.h>
#include <idt.h>

#define IDT_MAX_DESCRIPTORS 256

#define ATTR_KERN_32 0x8E // active(1), ring 0 (00), interrupt gate(0), 32 bit (1110)
#define ATTR_USER_32 0xEE // active, ring 3, 32bit

#define SEGMENT_KERN 0x08

extern void load_idt(void);
extern void enable_int(void);

extern void isr0();
extern void isr1();
extern void isr8();
extern void isr13();
extern void isr14();
extern void isr32();
extern void isr33();

void* isr_stub_table[256] = {
    [0] = isr0,
    [1] = isr1,
    [8] = isr8,
    [13] = isr13,
    [14] = isr14,
    [32] = isr32,
    [33] = isr33,
};

idt_entry idt[IDT_MAX_DESCRIPTORS];
idt_ptr idtr;

void set_idtr(uint8_t vector, void* isr, uint16_t sel, uint8_t attributes) {
    idt_entry* desc = &idt[vector];

    desc->isr_low    = (uint32_t)isr & 0xFFFF;
    desc->selector  = SEGMENT_KERN;
    desc->reserved   = 0;
    desc->attributes = attributes;
    desc->isr_high   = ((uint32_t)isr >> 16) & 0xFFFF;
}

void init_idt() {
    idtr.limit = (sizeof(idt_entry) * IDT_MAX_DESCRIPTORS) - 1;
    idtr.base  = (uint32_t)&idt;

    for (int i = 0; i < IDT_MAX_DESCRIPTORS; i++) {
        if (isr_stub_table[i] != 0) {
            set_idtr(i, isr_stub_table[i], SEGMENT_KERN, ATTR_KERN_32);
        } else {
            set_idtr(i, 0, SEGMENT_KERN, 0);
        }
    }

    extern void syscall_handler();
    set_idtr(0x80, syscall_handler, SEGMENT_KERN, ATTR_USER_32);

    load_idt();
}