46 lines
1.4 KiB
C
46 lines
1.4 KiB
C
/******************************************************************
|
|
* idt.h - INTERRUPT DESCRIPTOR TABLE *
|
|
* Contains structures and function declarations for IDT *
|
|
******************************************************************/
|
|
#include <system.h>
|
|
#include "idt.h"
|
|
|
|
extern void i86_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 i86_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* i86_IdtGetGate(unsigned char num)
|
|
{
|
|
return &idt[num];
|
|
}
|
|
|
|
/* Installs the IDT */
|
|
void i86_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 */
|
|
i86_IdtLoad();
|
|
}
|