gdt_begin:

gdt_null:
    dd 0x00
    dd 0x00
gdt_code:
    dw 0xffff
    dw 0x0000
    db 0x0
    db 10011010b
    db 11001111b
    db 0x0
gdt_data:
    dw 0xffff
    dw 0x0000
    db 0x0
    db 10010010b
    db 11001111b
    db 0x0
gdt_end:

gdt_descriptor:
    dw gdt_end - gdt_begin - 1
    dd gdt_begin

CODE_SEG equ gdt_code - gdt_begin
DATA_SEG equ gdt_data - gdt_begin