luxos/Kernel/hal/cpu/idt.c

/******************************************************************
 *    idt.h  -  INTERRUPT DESCRIPTOR TABLE                        *
 *      Contains structures and function declarations for IDT     *
 ******************************************************************/
#include <stdlib.h>
#include "idt.h"

extern void IdtLoad();
/* Declare an IDT of 256 entries.  */
struct IdtEntry idt[256];
struct IdtPointer idtp;

/* Use this function to set an entry in the IDT. Alot simpler
*  than twiddling with the GDT ;) */
void IdtSetGate(unsigned char num, unsigned long base, unsigned short sel, unsigned char flags)
{
    /* The interrupt routine's base address */
    idt[num].base_lo = (base & 0xFFFF);
    idt[num].base_hi = (base >> 16) & 0xFFFF;

    /* The segment or 'selector' that this IDT entry will use
    *  is set here, along with any access flags */
    idt[num].sel = sel;
    idt[num].always0 = 0;
    idt[num].flags = flags;
}

struct IdtEntry* IdtGetGate(unsigned char num)
{
      return &idt[num];
}

/* Installs the IDT */
void IdtInstall()
{
    /* Sets the special IDT pointer up, just like in 'gdt.c' */
    idtp.limit = (sizeof (struct IdtEntry) * 256) - 1;
    idtp.base = (unsigned int)&idt;

    /* Clear out the entire IDT, initializing it to zeros */
    memset (&idt, 0, sizeof(struct IdtEntry) * 256);

    /* Points the processor's internal register to the new IDT */
    IdtLoad();
}