IDT C code

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

extern int printf(const char *fmt, ...);

int interrupt_number;

struct idt_descriptor {
    uint16_t base_low;          /* first 16 bits of the base address of the IR */
    uint16_t selector;          /* segment selector */
    uint8_t  reserved;          /* reserved: always 0 */
    uint8_t  flags;             /* bits 39-41: flags, bits 42-45: DPL */
    uint16_t base_high;         /* bits 16-31 of the base address of the IR */
} __attribute__ ((packed));

struct idt_pointer {
    uint16_t limit;             /* size of the IDT */
    uint32_t base;              /* base address of the IDT */
} __attribute__ ((packed));

struct idt_descriptor idt_desc[MAX_INTERRUPTS];
struct idt_pointer idt_p;

/* default handler to catch unhandled system interrupts */

void interrupt_handler()
{
    printf("Unhandled exception ");

    while (1) {

    }
}

void set_interrupt_number(int num)
{
    interrupt_number = num;
}

void idt_set_gate(uint32_t i, uint64_t base, uint16_t selector, uint8_t flags)
{
    /*if (i > MAX_INTERRUPTS)
        return;*/

    /* The interrupt routine's base address */

    idt_desc[i].base_low    = (base & 0xFFFF);
    idt_desc[i].base_high   = (base >> 16) & 0xFFFF;

    /* The segment or 'selector' that this IDT entry will use
    *  is set here, along with any access flags */

    idt_desc[i].selector    = selector;
    idt_desc[i].reserved    = 0;
    idt_desc[i].flags       = flags;
}

void idt_install()
{
    idt_p.limit = (sizeof(idt_desc) * MAX_INTERRUPTS) - 1;
    idt_p.base  = (uint32_t) &idt_desc;

    /* null the entire IDT */

    memset(&idt_desc, 0, sizeof(idt_desc) * MAX_INTERRUPTS);

    /* install the new IDT */

    _idt_install();
}