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global load_gdt
%macro gdt_entry 4
db %2 & 0xff
db (%2 >> 8) & 0xff
db %1 & 0xff
db (%1 >> 8) & 0xff
db (%1 >> 16) & 0xff
db %3
db ((%2 >> 16) & 0x0f) | (%4 << 4)
db (%1 >> 24) & 0xff
%endmacro
section .rodata
align 16
gdt_start:
gdt_entry 0, 0, 0, 0
gdt_entry 0, 0xFFFFF, 0x9A, 0xC
gdt_entry 0, 0xFFFFF, 0x92, 0xC
gdt_end:
gdt_descriptor:
dw gdt_end - gdt_start - 1
dd gdt_start
section .text
align 8
load_gdt:
cli
lgdt [gdt_descriptor]
mov eax, cr0
or al, 1
mov cr0, eax
mov ax, 0x10
mov ds, ax
mov ss, ax
mov es, ax
mov fs, ax
mov gs, ax
jmp 0x08:after_gdt
after_gdt:
ret
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