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path: root/boot/GDT.asm
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gdt_start:

gdt_null:   ;null descriptor (2 x 4 bytes)
    dd 0x0
    dd 0x0

gdt_code:
    ; flags:
    ; present: 1 / privilege: 00 / type: 1
    ; code: 1 / conforming: 0 / readable: 1 / accessed: 0
    ; granularity: 1 / 32-bit default: 1 / 64-bit seg: 0 / AVL: 0
    dw 0xffff	    ;limit
    dw 0x0	    ;base
    db 0x0	    ;base
    db 10011010b    ;flags
    db 11001111b    ;flags & seg.limit
    db 0x0	    ;base

gdt_data:
    ; flags:
    ; code: 0 / expand down: 0 / writable: 1 / accessed: 0
    dw 0xffff
    dw 0x0
    db 0x0
    db 10010010b
    db 11001111b
    db 0x0

gdt_end:

gdt_descriptor:
    dw gdt_end-gdt_start-1
    dd gdt_start

CODE_SEG equ gdt_code - gdt_start
DATA_SEG equ gdt_data - gdt_start