mbr_asm/idt.c
Mathieu Maret f1341d3d72 Add some "kernel" code written in C
Draw few message on VGA
Setup Interruption Description Table
Setup IRQ
2017-11-27 14:51:51 +01:00

45 lines
1.0 KiB
C

#include "idt.h"
static struct idtEntry idt[IDT_NUM];
int idtSetup()
{
struct idtRegister idtr;
for (int i = 0; i < IDT_NUM; i++) {
struct idtEntry *idte = idt + i;
/* Setup an empty IDTE interrupt gate, see figure 5-2 in Intel
x86 doc, vol 3 */
idte->seg_sel = BUILD_SEGMENT_SELECTOR(RING_0, 0, SEGMENT_IDX_CODE);
idte->reserved = 0;
idte->flags = 0;
idte->type = 0x6; /* Interrupt gate (110b) */
idte->op_size = 1; /* 32bits instructions */
/* Disabled it for now */
idte->zero = 0;
idte->offset_low = 0;
idte->offset_high = 0;
idte->dpl = 0;
idte->present = 0;
}
/*
* Setup the IDT register, see Intel x86 doc vol 3, section 5.8.
*/
/* Address of the IDT */
idtr.base_addr = (uint32_t) idt;
/* The limit is the maximum offset in bytes from the base address of
the IDT */
idtr.limit = sizeof(idt) - 1;
/* Commit the IDT into the CPU */
asm volatile ("lidt %0\n"::"m"(idtr):"memory");
return 0;
}