-
Notifications
You must be signed in to change notification settings - Fork 2
/
idt.h
46 lines (38 loc) · 1.43 KB
/
idt.h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
#ifndef IDT_H
#define IDT_H
#include <stddef.h>
#include <stdint.h>
#include "io.h"
extern void load_idt(unsigned long *idt_ptr);
typedef struct idt_entry {
unsigned short int offset_low; // offset 0..15
unsigned short int selector; // code seg. selector in GDT (or LDT in future)
unsigned char zero; // just one byte, = 0
unsigned char type_and_attributes; // see below
unsigned short int offset_high; // offset 16..31
} idt_entry;
/* type_and_attributes
* 7 6 5 4 3 2 1 0
* +---+---+---+---+---+---+---+---+
* |Prs| DPL | S | Gate Type |
* +---+---+---+---+---+---+---+---+
*
* Prs = presnt bit : 1 for all active interrupts
* DPL = Descriptor privilege lvl
* S = storage seg: 0 for interrupt and trap gates, see gate type
* Gate Type = see below
*
* Gate types:
* +--------+-----+------+----------------------------------+
* | Binary | Hex | Dec. | Description |
* +--------+-----+------+----------------------------------+
* | 0101 | 0x5 | 5 | 80386 chip 32-bit TASK gate |
* | 0110 | 0x6 | 6 | 80286 chip 16-bit INTERRUPT gate |
* | 0111 | 0x7 | 7 | 80286 chip 16-bit TRAP gate |
* | 1110 | 0xe | 14 | 80386 chip 32-bit INTERRUPT gate |
* | 1111 | 0xf | 15 | 80386 chip 32-bit TRAP gate |
* +--------+-----+------+----------------------------------+
*/
idt_entry idt[256]; // 256 entries of the idt
void idt_init();
#endif