45 lines
897 B
C
45 lines
897 B
C
|
#ifndef GDT_H
|
||
|
|
#define GDT_H
|
||
|
|
|
||
|
|
#include "types.h"
|
||
|
|
|
||
|
|
// Access byte
|
||
|
|
#define GDT_AC 1 // Access bit
|
||
|
|
#define GDT_RW 1 << 1 // Read/Write bit
|
||
|
|
#define GDT_DC 1 << 2 // Direction bit/Conforming bit
|
||
|
|
#define GDT_EXEC 1 << 3 // Executable bit
|
||
|
|
#define GDT_S 1 << 4 // Descriptor type
|
||
|
|
#define GDT_PRVL_0 0 // Privilege (from 0 to 3)
|
||
|
|
#define GDT_PRVL_1 1 << 5
|
||
|
|
#define GDT_PRVL_2 2 << 5
|
||
|
|
#define GDT_PRVL_3 3 << 5
|
||
|
|
#define GDT_PR 1 << 7 // Present Bit
|
||
|
|
|
||
|
|
// Flags
|
||
|
|
#define GDT_SZ 1 << 2 // Size bit
|
||
|
|
#define GDT_GR 1 << 3 // Granularity bit
|
||
|
|
|
||
|
|
typedef struct GDT_ENTRY {
|
||
|
|
u32 base;
|
||
|
|
u32 limit;
|
||
|
|
u8 flags;
|
||
|
|
u8 access;
|
||
|
|
} GDT_ENTRY;
|
||
|
|
|
||
|
|
struct GDT_REGISTER {
|
||
|
|
u16 limit;
|
||
|
|
u32 base;
|
||
|
|
} __attribute__((packed));
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Copy GDT in memory
|
||
|
|
*/
|
||
|
|
void gdt_memcpy();
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Write a GDT entry at address addr
|
||
|
|
*/
|
||
|
|
void gdt_write_entry(GDT_ENTRY entry, u32 addr);
|
||
|
|
|
||
|
|
#endif
|