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
47
48
49
50
51
|
#include "gdt.h"
#include <stdint.h>
uint8_t make_access(uint8_t DPL, uint8_t type, uint8_t exec, uint8_t direction,
uint8_t read_write) {
uint8_t access = 0;
access |= (1 << 7);
access |= (DPL << 5);
access |= (type << 4);
access |= (exec << 3);
access |= (direction << 2);
access |= (read_write << 1); // 10
return access;
}
uint16_t make_code(uint8_t priv, uint8_t dc, uint8_t rw) {
uint16_t access = 0;
access |= (1 << 7);
access |= (priv << 5);
access |= (0b11 << 3);
access |= (dc << 2);
access |= (rw << 1); // 10
access <<= 8;
access |= FLAG;
return access;
}
uint16_t make_data(uint8_t priv, uint8_t dc, uint8_t rw) {
uint16_t access = 0;
access |= (1 << 7);
access |= (priv << 5);
access |= (0b10 << 3);
access |= (dc << 2);
access |= (rw << 1); // 10
access <<= 8;
access |= FLAG;
return access;
}
Segment_Descriptor_t make_descriptor(uint32_t base, uint32_t limit,
uint16_t access_flag) {
uint16_t lim_low = limit;
uint16_t base_low = base;
uint8_t base_mid = (base >> 16);
uint8_t access_byte = access_flag >> 8;
uint8_t lim_flag = ((access_flag << 4) | (limit >> 16));
uint8_t base_high = (base >> 24);
return (Segment_Descriptor_t){
lim_low, base_low, base_mid, access_byte, lim_flag, base_high,
};
}
|
