gdt.c File Reference

#include <stdint.h>
#include <string.h>

Data Structures
struct	gdt_entry
struct	gdt_description
struct	tss_entry

Macros
#define	NUM_ENTRIES   6
	Number of entries in the GDT.

Functions
static void	set_entry (int i, uint32_t base, uint32_t limit, uint8_t access)
static void	write_tss (int32_t num, uint16_t ss0, uint32_t esp0)
void	allow_all_ports ()
void	block_all_ports ()
void	gdt_init ()

Variables
uint32_t	int_stack_top
	Initial kernel stack before the kernel's first yield.
static gdt_entry	gdt [NUM_ENTRIES]
	The GDT.
static gdt_description	gdt_desc
	The value to load into the GDTR.
tss_entry	tss
	The TSS.

Function Documentation

allow_all_ports()

void allow_all_ports

(

)

Allows all ports in the IOPB.

block_all_ports()

void block_all_ports

(

)

Blocks all ports in the IOPB.

gdt_init()

void gdt_init

(

)

Initializes the GDT & TSS.

set_entry()

static void set_entry ( int  i, uint32_t  base, uint32_t  limit, uint8_t  access  )

static

Set a GDT entry.

Parameters

i	The GDT entry to set.
base	The base of the GDT entry.
limit	The limit of the GDT entry.
access	The access byte of the GDT entry.

write_tss()

static void write_tss ( int32_t  num, uint16_t  ss0, uint32_t  esp0  )

static

Set a GDT entry.

Parameters

num	The GDT entry to set.
ss0	The kernel stack selector.
esp0	The kernel stack pointer.